DOI: 10.1038/NCHEM - Nature · NATURE CHEMISTRY | 3 DOI: 10.1038/NCHEM.1870 SUPPLEMENTARY INFORMATION S3 1. Syntheses (i) General methods and instrumentation

NATURE CHEMISTRY | www.nature.com/naturechemistry 1

SUPPLEMENTARY INFORMATIONDOI: 10.1038/NCHEM.1870

S1

Stable GaX2, InX2 and TlX2 radicals

Andrey V. Protchenko,1 Deepak Dange,2 Jeffrey R. Harmer,3,4 Christina Y. Tang,1 Andrew D.

Schwarz,1 Michael J. Kelly,1 Nicholas Phillips,1 Remi Tirfoin,1 Krishna Hassomal Birjkumar,5

Cameron Jones,2 Nikolas Kaltsoyannis,5 Philip Mountford1 and Simon Aldridge1

1 Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks

Road, Oxford, UK OX1 3QR.

2 School of Chemistry, PO Box 23, Monash University, Melbourne, VIC, 3800, Australia.

3 Centre for Applied Electron Spin Resonance, Department of Chemistry, University of Oxford,

OX1 3QR.

4 Center for Advanced Imaging, University of Queensland, St Lucia, QLD, 4072, Australia.

5 Department of Chemistry, University College London, Christopher Ingold Laboratories, 20

Gordon Street, London, UK WC1H 0AJ.

Supplementary Information (42 pages)

© 2014 Macmillan Publishers Limited. All rights reserved.


SUPPLEMENTARY INFORMATIONDOI: 10.1038/NCHEM.1870S2

1. Syntheses S3 2. Magnetic susceptibility measurements S8

3. X-ray crystallographic studies S9 4. Computational details S18

5. EPR spectroscopy S26 6. Cyclic voltammetry measurements S33

7. UV/Vis spectroscopy S34 8. References for supporting information S41




1. Syntheses (i) General methods and instrumentation

All manipulations were carried out using standard Schlenk line or dry-box techniques under an atmosphere of argon or dinitrogen. Solvents were degassed by sparging with dinitrogen and dried by passing through a column of the appropriate drying agent. Tetrahydrofuran (thf) and diethyl ether were refluxed over sodium-potassium alloy and distilled. NMR spectra were measured in benzene-d6 or thf-d8 which had been dried over sodium or potassium, distilled under reduced pressure and stored under dinitrogen in a Teflon valve ampoule. NMR samples were prepared under dinitrogen in 5 mm Wilmad 507-PP tubes fitted with J. Young Teflon valves. 1H, 13C{1H}, and 11B{1H} NMR spectra were measured on a Varian Mercury-VX-300 or a Bruker AvanceIII 400 spectrometer at ambient temperature unless otherwise stated, and referenced internally to residual protio-solvent (1H) or solvent (13C) resonances, and are reported relative to tetramethylsilane (δ = 0 ppm). 11B NMR spectra were referenced to external Et2O·BF3. Assignments were confirmed using two dimensional 1H-1H and 13C-1H NMR correlation experiments. Chemical shifts are quoted in δ (ppm) and coupling constants in Hz. Elemental analyses were carried out by London Metropolitan University. Small-scale crystallizations were carried out in λ-shaped glass tubes flame-sealed under vacuum, thus allowing easy transfer of solvent vapour or solution from one leg into another and prolonged crystallization in a range of temperatures avoiding the risk of contamination by grease or oxygen.

(ii) Starting materials (thf)2Li{B(NDippCH)2} (1), In{N(SiMe3)Dipp*}, Ga{N(SiMe3)Dipp*}, Tl{N(SiMe3)2} and Sm(η5-C5Me5)2(thf) were synthesised according to published procedures.8,33-35 The structure of [K(18-crown-6)(thf)2][C10H8] was reported previously without synthetic details,36 and was prepared as follows: A solution of naphthalene (250 mg, 1.95 mmol) and 18-crown-6 (380 mg, 1.44 mmol) in thf (15 mL) was added to a chunk of potassium (56 mg, 1.43 mmol). The mixture was stirred at room temperature using a glass-coated stirrer bar for 3 h until all the metal had dissolved. After settling for 30 min., the solution was carefully decanted via a cannula and slowly evaporated in vacuo. The resulting black crystals were washed with hexane and dried in vacuo. 1H NMR spectroscopy in thf-d8 showed that the product was thf-free, otherwise the spectrum was non-informative due to paramagnetism. Yield 534 mg (1.24 mmol, 86%).

(iii)Syntheses of novel compounds Ga{B(NDippCH)2}2Cl (3-Ga). A solution of 1 (404 mg, 0.75 mmol) in hexane (20 mL) was added to a stirred solution of GaCl3 (66 mg, 0.375 mmol) also in hexane (10 mL) at −30 °C; the mixture was stirred for 30 min at −30 °C and then warmed to room temperature. After stirring for 2 h a colorless powder appeared in the yellow solution; the solution was decanted and concentrated to ca. one third of its volume producing a significant amount of microcrystalline precipitate. Storing at −30 °C overnight produced further colorless needles, then large yellow plates after 2 d. This material was extracted with hot hexane and crystallized at room temperature yielding large colorless blocks of Ga{B(NDippCH)2}2Cl (190 mg, 0.22 mmol, 58%). Elemental/combustion analysis, found (calcd. for C52H72B2ClGaN4): C, 70.76 (70.98)%; H, 8.37 (8.25)%; N, 6.47 (6.37)%. 1H NMR (C6D6): δ 7.18 (t, 3J(H,H) = 7.8 Hz, 4 H, p-H of Ar), 7.03 (d, 3J(H,H) = 7.8 Hz, 8 H, m-H of Ar), 6.10 (s, 4 H, NCH), 3.19 (sept, 3J(H,H) = 6.9 Hz, 8 H, CHMe2), 1.11 (d, 3J(H,H) = 6.9 Hz, 24 H, CHMe2), 0.99 (d, 3J(H,H) = 6.9 Hz, 24 H, CHMe2).




13C NMR (C6D6): δ 146.3 (o-C of Ar), 139.7 (ipso-C of Ar), 127.9 (p-CH of Ar), 123.7 (m-CH of Ar), 122.0 (NCH), 28.5 (CHMe2), 25.4 and 24.4 (CHMe2). 11B NMR (C6D6): δ 30.5 (br).

In{B(NDippCH)2}2Cl (3-In). A solution of 1 (256 mg, 0.49 mmol) in benzene (5 mL) was added to a suspension of InCl3 (54 mg, 0.25 mmol) also in benzene (5 mL) at room temperature. After stirring for 30 min, volatiles were removed and the residue dried in vacuo for 1 h. The product was extracted with benzene (2×5 mL), the extract evaporated in vacuo and the resulting sticky solid recrystallized from warm hexane yielding colorless plate-like crystals of In{B(NDippCH)2}2Cl (173 mg, 0.19 mmol, 75%). 1H NMR (C6D6): δ 7.18 (t, 3J(H,H) = 7.8 Hz, 4 H, p-H of Ar), 7.03 (d, 3J(H,H) = 7.8 Hz, 8 H, m-H of Ar), 6.10 (s, 4 H, NCH), 3.19 (sept, 3J(H,H) = 6.9 Hz, 8 H, CHMe2), 1.11 (d, 3J(H,H) = 6.9 Hz, 24 H, CHMe2), 0.99 (d, 3J(H,H) = 6.9 Hz, 24 H, CHMe2). 13C NMR (C6D6): δ 146.4 (o-C of Ar), 139.6 (ipso-C of Ar), 127.7 (p-CH of Ar), 123.7 (m-CH of Ar), 122.1 (NCH), 28.5 (CHMe2), 25.4, 24.5 (CHMe2). 11B NMR (C6D6): δ 36.5 (br). Ga{B(NDippCH)2}2 (2-Ga). To a stirred solution of Ga{N(SiMe3)Dipp*} (160 mg, 0.28 mmol) in toluene (15 mL) was added a solution of 1 (300 mg, 0.56 mmol) in toluene (15 mL) at –78 °C. The solution was slowly warmed to 0 °C over a period of 5 h while it turned dark green in color. A toluene solution of 12-crown-4 (100 mg, 0.56 mmol) was then added to the reaction mixture. The resulting solution was stirred at ambient temperature for 1 h whereupon all volatiles were removed in vacuo. The solid was extracted into pentane (2 × 8 mL) and filtered. The extract was concentrated to ca. 10 mL and stored at –30 °C overnight to give orange-red crystals of 2-Ga (150 mg, 64%); mp 132-134 °C (dec.). Elemental/combustion analysis, found (calcd. for C52H72B2GaN4): C, 74.08 (73.96)%; H, 8.65 (8.59)%; N, 6.68 (6.63)%. 1H NMR (C6D6, 400 MHz, 296 K): δ 7.37 (br), 6.83 (br), 3.10 (br), –0.67 (br), –2.07 (br). IR (Nujol) ν/cm–1: 1560 (w), 1240 (m), 1060 (m), 1035 (w), 802 (s), 757 (s). MS EI: m/z (assignment, %) 388.3 [HB(NDippCH)2

+, 100].

A small amount of compound Ga2{B(NDippCH)2}3 (4-Ga) was isolated from the preparation of 2-Ga. Compound 4-Ga crystallises as green crystals after isolating two crops of 2-Ga and keeping the mother liquor for a few days at –30 °C; mp 136-138 °C (dec.). IR (Nujol) ν/cm–1: 1588 (w), , 1102 (s), 1057 (m), 1019 (w), 802(s), 758(s); MS EI: m/z (assignment, %) 1301.7 [M+, 3], 388.3 [HB(NDippCH)2

+, 100]. (2-In). Method A. To a stirred solution of In{N(SiMe3)Dipp*} (170 mg, 0.28 mmol) in toluene (15 mL) was added a solution of 1 (300 mg, 0.56 mmol) in toluene (15 mL) at –78 °C. The solution was slowly warmed to 0 °C over a period of 5 h while it turned dark green in color. A toluene solution of 12-crown-4 (100 mg, 0.56 mmol) was then added to the reaction mixture. The resulting solution was stirred at ambient temperature for 1 h whereupon all volatiles were removed in vacuo. The solid was extracted into pentane (2 × 8 mL) and filtered. The extract was concentrated to ca. 10 mL and stored at –30 °C overnight to give orange-red crystals of 2-In (94 mg, 38%); mp 196-198 °C (dec.). Elemental/combustion analysis, found (calcd. for C52H72B2InN4): C, 70.17 (70.21)%; H, 8.21 (8.16)%; N, 6.37 (6.30)%. 1H NMR (C6D6, 400 MHz, 296 K): δ 7.59 (br), 7.12 (br), 3.45 (br), 2.67 (br), –0.76 (br). IR (Nujol) ν/cm–1: 1405 (w), 1134 (s), 1131 (s), 1021 (m), 804 (s), 759 (m). MS EI: m/z (assignment, %) 889.5 [M+, 5], 388.2 [HB(NDippCH)2

+, 100]. Method B. A chunk of K metal (7.8 mg, 0.20 mmol) was added to a solution of ClIn(B(NDippCH)2)2, 3-In (80 mg, 0.086 mmol) in C6D6 (~0.6 mL), the mixture was degassed




by freeze-pump-thaw and thf (~0.05 mL) was condensed onto the mixture. (Without thf, the reduction was too slow as only trace of 2-In could be detected by 1H-NMR after 2 h sonication). The tube was placed into ultrasonic bath and sonicated for 2.5 h until the 3-In starting material had disappeared (as judged by 1H NMR spectroscopy); by this point the colour had changed to very dark brown and the initially formed broad signals of 2-In had disappeared. To prevent over-reduction excess potassium was avoided. A chunk of potassium metal (2.0 mg, 0.051 mmol) was added to a solution of 3-In (50 mg, 0.054 mmol) in C6D6 (~0.6 mL), the mixture degassed by freeze-pump-thaw and thf (~0.05 mL) was condensed onto the mixture. After sonication for ca. 2 h the NMR tube contents were transferred into a crystallisation tube and volatiles removed in vacuo. The residue was extracted with hexane and the sealed tube was stored in at 0 oC for 2 d, yielding two types of crystals: large orange needles (major) and very thin brown-purple needles (minor, less soluble). X-ray diffraction study showed that the orange needles were co-crystals of 2-In (85%) and 3-In (15%). In order to characterise the second product, the reaction was repeated and the mixture of products was heated with hexane to ~55 °C in a sealed tube until the dark crystals dissolved and then slowly cooled. Leaving the tube undisturbed for 1 week resulted in the formation of brown-purple needles of sufficient thickness for X-ray diffraction study, which shown that this compound was the dinuclear indium boryl complex [In2(B(NDippCH)2)3] (4-In).

Method C. Solid Sm(h5-C5Me5)2(thf) (155 mg, 0.31 mmol) was added to a solution of 3-In (290 mg, 0.31 mmol) in C6H6 (~10 mL) producing a dark brown solution. The volatiles were removed in vacuo and hexane (~20 mL) was added. The mixture was filtered and the concentrated filtrate was stored at –30 °C overnight yielding large red needles of 2-In and small orange-yellow polycrystalline Sm(h5-C5Me5)2Cl(thf) (identified by its 1H NMR spectrum). The crystals of 2-In were separated manually and recrystallised again yielding pure 2-In (185 mg, 0.21 mmol, 67%).

Tl{B(NDippCH)2}2 (2-Tl). Method A. Powdered TlCl (100 mg, 0.41 mmol) was suspended in hexane (2 mL) and a solution of 1 (225 mg, 0.41 mmol) in hexane (6 mL) added at −78 °C (1 precipitated at this temperature forming a thick suspension). The reaction mixture was warmed up to room temperature resulting in the solution turning brown and, after several hours, orange (the precipitate turned brown, then black with metallic lustre). After stirring overnight at room temperature, a bright orange solution and a black precipitate were evident. The solution was transferred via cannula with a fibreglass filter into a λ-tube and the precipitate was extracted with hexane (2 mL). The combined solution was slowly evaporated until crystallisation started and then stored at 0 °C overnight. A first crop of red-orange crystals was separated by decanting the solution, washing with cold hexane and drying in vacuo (108 mg, 0.11 mmol, 54% based on 1); from the remaining solution another crop of 2-Tl was isolated in a similar way (43 mg, 0.04 mmol, 21% based on 1; combined yield 75%); mp 225-230 °C (dec.). Elemental/combustion analysis, found (calcd. for C52H72B2N4Tl): C, 63.89 (63.78)%; H, 7.50 (7.41)%; N, 5.87 (5.72)%. MS EI: m/z (assignment, %) 979 [M+, 70], 387 [(ArNCH)2B+, 100], 203 [203Tl+, 30], 205 [205Tl+, 80]. 1H NMR (C6D6): δ 7.92 (br), 7.81 (br), 1.69 (br), 0.22 (br), –2.43 (br).

Method B. A solution of 1 (236 mg, 0.44 mmol) in hexane (5 mL) was added to a solution of TlN(SiMe3)2 (160 mg, 0.44 mmol) in hexane (5 mL) at −45 °C. Initially, a purple-red colour appeared, turning bright green upon completion of the addition of 1, then changing to dark green-brown in a few seconds. The solution was transferred into a λ-tube, concentrated until crystallisation started and stored at 0oC overnight. A crop of red-orange crystals of 2-Tl was separated by decanting the solution, washing with cold hexane and drying in vacuo (113 mg,




0.12 mmol, 82% based on stoichiometry shown below). The remaining solution (now more green) was concentrated again until some black crystals appeared (but before orange crystals started to precipitate) and stored in a freezer at −30 °C for several days. The solution was decanted, the black crystals of Tl8{B(NDippCH)2}4 washed with cold hexane and dried in vacuo; isolated yield of single crystals 26 mg (0.008 mmol, 22% based on stoichiometry shown below). 1H NMR (C6D6): δ 7.30 (t, 3J(H,H) = 7.6 Hz, 8 H, p-H of Ar), 7.19 (d, 3J(H,H) = 7.6 Hz, 16 H, m-H of Ar), 6.62 (s, 8 H, NCH), 3.24 (sept, 3J(H,H) = 6.9 Hz, 16 H, CHMe2), 1.35 (d, 3J(H,H) = 6.9 Hz, 48 H, CHMe2), 1.27 (d, 3J(H,H) = 6.9 Hz, 48 H, CHMe2). 13C NMR (C6D6): δ 145.8 (o-C of Ar), 140.0 (ipso-C of Ar), 127.9 (p-CH of Ar), 126.5 (NCH), 124.1 (m-CH of Ar), 28.6 (CHMe2), 26.8, 25.0 (CHMe2). 11B NMR (C6D6): δ 205.8 (br). Reaction stoichiometry: 12 Tl{N(SiMe3)2} 12 Li{N(SiMe3)2} + 4 TlII{B(NDippCH)2}2

+ 12 (thf)2Li{B(NDippCH)2} + Tl04TlI

4{B(NDippCH)2}4

[Tl{B(NDippCH)2}2][B(C6F5)4] ([2-Tl][B(C6F5)4]). An orange solution of 2-Tl (20 mg, 0.0204 mmol) in C6D6 (0.3 mL) was added to a suspension of [Ph3C][B(C6F5)4] (18.8 mg, 0.0204 mmol) also in C6D6 (0.3 mL) forming a yellow suspension. 1H NMR spectroscopy showed the signals belonging to Gomberg dimer. Recrystallization from Et2O/hexane gave yellow crystals of [2-Tl][B(C6F5)4]− suitable for X-ray crystallography.

[Tl{B(NDippCH)2}2][B{C6H3(CF3)2-3,5}4] ([2-Tl][B{C6H3(CF3)2-3,5}4]). A solution of 2-Tl (56 mg, 0.057 mmol) in Et2O (1 mL) was added to a dark blue solution of [Fe(h5-C5H5)2][B(C6H3(CF3)2-3,5)4] (60 mg, 0.057 mmol) also in Et2O (2 mL) forming a yellow solution. Volatiles were removed in vacuo and the residue washed with hexane (2 × 3 mL; evaporation of hexane left light orange crystals of ferrocene). The washed yellow solid was dried in vacuo yielding [2-Tl][B(C6H3(CF3)2-3,5)4] (0.103 g, 0.056 mmol, 98%). Elemental/combustion analysis, found (calcd. for C84H84B3F24N4Tl): C, 53.94 (54.76)%; H, 4.14 (4.60)%; N, 3.56 (3.04)%. 1H NMR (C4D8O): δ 7.81 (br m, 8 H, o-CH of BArf

4), 7.60 (br s, 4 H, p-CH of BArf

4), 7.43 (t, 3J(H,H) = 7.9 Hz, 4 H, p-H of Ar), 7.23 (d, 3J(H,H) = 7.9 Hz, 8 H, m-H of Ar), 6.68 (br s, 4 H, NCH), 2.79 (sept, 3J(H,H) = 6.9 Hz, 8 H, CHMe2), 1.09 (d, 3J(H,H) = 6.9 Hz, 24 H, CHMe2), 0.89 (d, 3J(H,H) = 6.9 Hz, 24 H, CHMe2). 13C{1H} NMR (C4D8O): δ 163.1 (q, 1J(13C,11B) = 49.7 Hz, ipso-C of BArf

4), 146.5 (o-C of Ar), 137.4 (ipso-C of Ar), 135.9 (br s, o-CH of BArf

4), 130.3 (p-CH of Ar), 125.8 (q, 1J(13C,19F) = 272 Hz,CF3), 125.7 (m-CH of Ar), 118.5 (br m, p-CH of BArf

4), 29.8 (CHMe2), 25.78 (CHMe2), 25.22 (CHMe2). The m-C signal of BArf

4 was not observed; the NCH resonance was not observed directly, but there is a cross-peak at ca. 122.2 ppm in gHSQC spectrum]. 19F NMR (C4D8O): δ –61.4. 11B NMR (C4D8O): δ 67.7 (br d, 1J(11B,203/205Tl) = 3900 Hz, boryl), −4.7 (s, borate).

[K(18-crown-6)][Tl{B(NDippCH)2}2] ([K(18-crown-6)][2-Tl]). Solid 2-Tl (84.5 g, 0.0863 mmol) and [K(18-crown-6)][C10H8] (49.7 g, 0.115 mmol) were cooled to -196 oC and thf (ca. 1 mL) condensed onto the mixture. The reaction mixture was slowly warmed to room temperature (low solubility of the potassium naphthalenide hampered reaction at low temperature) and stirred until all the reagents had completely dissolved. Volatiles were removed from the resulting dark red-brown solution in vacuo and the crystalline residue washed with hexane (to remove naphthalene) and dried. In order to obtain X-ray quality crystals, approximately half of the material was transferred into a λ-tube and dissolved in Et2O (ca. 1 mL); black crystalline




precipitate started to form almost immediately, so the solution was quickly transferred into the second leg of the tube where slow crystallisation produced black rhombic crystals of [K(18-crown-6)][2-Tl].(OEt2). (15 mg, 0.011 mmol, 26% based on 2-Tl). The crystalline compound is stable as a solid under an inert atmosphere at room temperature for months, but decomposes in minutes in thf-d8 solution. Elemental/combustion analysis, found (calcd. for C68H106B2KN4O7Tl): C, 60.01 (60.20)%; H, 8.03 (7.88)%; N, 4.17 (4.13)%. 1H NMR (C4D8O): δ 6.87 (t, 3J(H,H) = 7.9 Hz, 4 H, p-H of Ar), 6.75 (d, 3J(H,H) = 7.9 Hz, 8 H, m-H of Ar), 6.38 (br s, 4 H, NCH), 3.64 (br s, 24 H, OCH2), 3.35 (sept, 3J(H,H) = 6.9 Hz, 8 H, CHMe2), 0.98 (d, 3J(H,H) = 6.9 Hz, 24 H, CHMe2), 0.73 (d, 3J(H,H) = 6.9 Hz, 24 H, CHMe2). 11B NMR (C4D8O): δ 180.7 (br d, 1J(11B,203/205Tl) = 3010 Hz).




2. Magnetic susceptibility measurements A variation of the Evans’ method designed for large weakly paramagnetic molecules has been used.37 Firstly, a solution of exactly 50.0 mg (estimated error ±0.5 mg) of the diamagnetic analogue Hg{B(NDippCH)2}2 (Mdia = 975.37) was prepared in C6D5CD3 (~0.5 mL) containing a SiMe4 standard and the 1H NMR spectrum measured; a capillary containing the same solvent was inserted into the NMR tube and variable temperature 1H NMR spectra then measured. When the spectrum was referenced to the larger SiMe4 signal, the additional smaller signal appeared at 0.020 to 0.023 ppm in the range –20 to +40 °C (δνdia = –6.69 Hz at 293 K). Subsequently, a sample of 2-Tl (M p = 979.16, m p = 50.0 mg) was dissolved in the same solvent (~0.4 mL), the solution volume adjusted to the same level as for the Hg{B(NDippCH)2}2 measurement and the same capillary inserted. Now the additional smaller signal appeared at –0.116 ppm at +20 °C (δνp = 34.61 Hz at 293 K).

(eqn S1)

(eqn S2)

Calculation based on equations (S1) and (S2) taken from ref. 37 gave the molar susceptibility χM = 6.44 10−

4 and magnetic moment µeff = 1.23 µB. Applying the same technique, two samples of Cd{B(NDippCH)2}2 (Mdia = 887.19) were prepared with mdia = 10.0 and 25.5 mg, showing δνdia = –1.35 and –3.13 Hz at 293 K. Then, two samples of 2-In (M p = 889.59, m p = 10.0 and 25.5 mg) were prepared showing δνp = 22.90 and 56.10 Hz at 293 K, from which molar susceptibilities of χM = 1.71 x 10−

3 and 1.64 x 10−3, and

magnetic moments of µeff = 2.01 and 1.97 µB, respectively, were determined. Similarly, a sample of Zn{B(NDippCH)2}2

38 (Mdia = 840.16) was prepared with mdia = 17.2 mg, showing δνdia = –2.03 Hz at 293 K. Then, a sample of 2-Ga (M p = 844.50, m p = 17.2 mg) was prepared showing δνp = 43.60 Hz at 293 K, which gave the molar susceptibility χM = 1.78 10−

3 and magnetic moment µeff = 2.04 µB.




3. X-ray crystallographic studies Crystallographic measurements for 2-Ga, 2-In, 2-Tl, 3-Ga, 3-In, 4-Ga, 4-In, Tl8{B(NDippCH)2}4, [K(18-crown-6)][2-Tl], [2-Tl][B{C6H3(CF3)2-3,5}], Cd{B(NDippCH)2}2, Hg{B(NDippCH)2}2 and Pb{B(NDippCH)2}2 were made using a Enraf-Nonius Kappa CCD diffractometer at 150(2) K using MoΚα radiation or an Oxford Diffraction SuperNova operating at 150(2) K using CuΚα radiation. The structures were solved with SIR92,39 Superflip,40 or SHELXS-97,41 and further refinements and all other crystallographic calculations were performed using either the CRYSTALS program suite or SHELXS-97.41,42 Further information relating to the individual structure solutions/refinements is given in Supplementary Table 1, and complete details (in the form of a CIF) is available for each structure from the Cambridge Crystallographic Data Centre with the following CCDC reference numbers: 2-Ga, 950733; 2-In, 950740; 2-Tl, 950734; 3-Ga, 950741; 3-In, 950735; 4-Ga, 950742; 4-In, 950736; Tl8{B(NDippCH)2}4, 957418; [K(18-crown-6)][2-Tl], 950739; [2-Tl][B{C6H3(CF3)2-3,5}], 950732.

Supplementary Table 1: Crystal data for 2-Ga, 2-In, 2-Tl, Tl8{B(NDippCH)2}4, [2-Tl][B{C6H3(CF3)2-3,5}], [K(18-crown-6)][2-Tl], 3-Ga, 3-In, 4-Ga.C5H12 and 4-In.C6H14.

Crystal data 2-Ga 2-In 2-Tl Tl8{B(NDippCH)2}4 [2-Tl] [B{C6H3(CF3)2-3,5}]

Formula C52H72B2GaN4 C52H72B2InN4 C52H72B2TlN4 C104H144B4N8Tl8 C84H83.5B3F24N4Tl Mr 844.98 889.58 979.13 3184.55 1841.88 Cell setting Space group

monoclinic P 21/n

monoclinic P 21/c

monoclinic P 21/n

trigonal P 31 2 1

triclinic P -1

a, b, c (Å) 12.9571(3) 26.6951(7) 14.4634(4)

15.3687(3) 12.8915(3) 25.1970(6)

12.9615(3) 16.6810(7) 14.7143(4)

15.9200(1) 15.9200(1) 41.3580(3)

14.5830(3) 16.6635(3) 17.8117(3)

α , β , γ (o) 90 91.502(2) 90

90 92.979(2) 90

90 91.285(2) 90

90 90 120

90.913(1) 90.085(1) 90.010(1)

V (Å3) 5001.0(2) 4985.4(2) 5087.3(2) 9077.7(1) 4327.8(1) Z 4 4 4 6 2 Dx 1.122 1.185 1.278 1.747 1.413 µ (mm-1) 0.587 0.511 3.211 10.650 4.426 Tmin, Tmax 0.84, 0.89 0.88, 0.95 0.64, 0.74 0.52, 0.65 0.44, 0.64 R[I > 2σ(I)] 0.0369 0.0340 0.0362 0.0572 0.0740 wR(I) 0.0904 0.0823 0.0797 0.1213 0.1832 S 1.017 1.044 1.074 0.894 1.027 Δρmax, Δρmin (e Å-

3) 0.37, -0.27 0.61, -0.39 1.72, -0.99 2.04, -1.92 2.15, -1.68

CCDC reference 950733 950740 950734 957418 950732

[K(18-crown-6)] [2-Tl].OEt2

3-Ga 3-In 4-Ga.C5H12 4-In.C6H14

C68H106B2KN4O7Tl C52H72B2ClGaN4 C52H72B2ClInN4 C83H120B3Ga2N6 C84H122B3In2N6 1356.70 879.96 925.06 1371.72 1478.00 triclinic P -1

monoclinic P 21/n

monoclinic P 21/c

monoclinic P 21/c

monoclinic P 21/c

13.7850(4) 15.7976(6) 17.3879(7)

12.5784(1) 20.9156(2) 19.7266(2)

21.3715(5) 12.5737(4) 19.9188(6)

12.9949(4) 27.9799(9) 21.0156(7)

20.9982(4) 12.7466(2) 30.7336(5)

80.737(3) 90 90 90 90




80.065(3) 71.124(3)

92.921(1) 90

98.863(2) 90

96.575(3) 90

98.730(2) 90

3506.7(2) 5183.0(1) 5288.6(3) 7952.1(4) 8130.7(2) 2 4 4 4 4 1.285 1.128 1.162 1.147 1.207 5.355 0.618 0.533 0.723 4.860 0.34, 0.34 0.85, 0.94 0.80, 0.99 0.82, 0.93 0.78, 0.78 0.0395 0.0419 0.0652 0.0405 0.0404 0.0307 0.1032 0.1598 0.0968 0.0150 1.085 0.941 1.007 1.023 1.053 2.14, -1.58 0.76, -0.66 1.21, -0.91 0.58, -0.36 0.97, -1.51 950739 950741 950735 950742 950736



SUPPLEMENTARY INFORMATIONDOI: 10.1038/NCHEM.1870

Supplementary Figure 1: Molecular structure of Tl8{B(NDippCH)2}4 in the solid state as determined by X-ray crystallography (ellipsoids shown at the 50% probability level; C-bound hydrogen atoms omitted and Dipp groups shown in wireframe format for clarity).

[B]

Tl

Tl

Tl

Tl

Tl

Tl

Tl

Tl[B]

[B]

[B]

[B] = B(NDippCH)2




Supplementary Figure 2: Molecular structures of ClGa{B(NDippCH)2}2 (3-Ga, panel a), ClIn{B(NDippCH)2}2 (3-In, panel b), Ga2{B(NDippCH)2}3 (4-Ga, panel c) and In2{B(NDippCH)2}3 (4-In, panel d) in the solid state as determined by X-ray crystallography (ellipsoids shown at the 50% probability level; C-bound hydrogen atoms omitted and iPr groups shown in wireframe format for clarity).

b a

c d




Supplementary Figure 3: Molecular structure of the cationic component of [Tl{B(NDippCH)2}2][B{C6H3(CF3)2-3,5}] ([2-Tl][B{C6H3(CF3)2-3,5}]) in the solid state as determined by X-ray crystallography (ellipsoids shown at the 40% probability level; C-bound hydrogen atoms and second disorder component omitted, and iPr groups shown in wireframe format for clarity).




Explanations of A and B level alerts in CIFs 2-Ga Alert level B

PLAT220_ALERT_2_B Large Non-Solvent C Ueq(max)/Ueq(min) ... 4.3 Ratio

Author Response: the Level B alert results from the presence of isopropyl groups. It is common for the methyl carbon atoms of isopropyl groups of 2,6-diisopropylphenyl substituents to display a degree of rotolibration. This gives rise to larger values of Ueq for these carbon atoms relative to the Ueq values for the more rigidly held aromatic carbons. In the present structure, the possibility of disorder of the isopropyl methyl groups over two or more sites was explored, though no suitable model was found. The identity of the atoms with higher than normal Ueq values as isopropyl carbon atoms is unambiguous.

2-Tl

Alert level B



Tl8{B(NDippCH)2}4

Alert level B

PLAT213_ALERT_2_B Atom C102 has ADP max/min Ratio ..... 4.6 oblate

Author Response: Four isopropyl groups were found to be disordered in the structure and were subsequently modelled. Atom C102, in particular, corresponds to a methyl group on one of the disordered groups. This also affects C100, C200 and C201. C57 is also disordered due to lateral movement of the aromatic ring

PLAT342_ALERT_3_B Low Bond Precision on C-C Bonds ............... 0.0237 Ang.




Author Response: Structure contains 24 Tl atoms per unit cell which dominates diffraction leading to relatively poor location of lighter elements.

[2-Tl][B{C6H3(CF3)2-3,5}]

Alert level A

PLAT245_ALERT_2_A U(iso) H4121 Smaller than U(eq) C412 by ... 0.129 AngSq

Author Response: This structure is highly disordered. No metrics should be discussed. The structure is included as further evidence of connectivity. The three hydrogen atoms that give rise to PLAT245 alert level A’s are bound to a highly prolate carbon atom that is part of a disordered fragment modeled across two positions. Modelling this fragment across two further positions did not improve the fit of the model to the data.





Alert level B


Author Response: This structure is highly disordered. No metrics should be discussed. The structure is included as further evidence of connectivity. Due to the disorder, many atoms are excessively prolate, giving rise to these alerts. Further modelling did not improve the fit of the model to the data.


Author Response: This structure is highly disordered. No metrics should be discussed. The structure is included as further evidence of connectivity. Due to the disorder, many atoms are excessively prolate, giving rise to these alerts. Further modelling did not improve the fit of the model to the data.




3-Ga

Alert level B



3-In

Alert level B

PLAT029_ALERT_3_B _diffrn_measured_fraction_theta_full Low ....... 0.943

Author Response: Unsuccessful attempts have been made to collect a better set of data due to inherently poor crystal quality. No attempt is made to discuss the structural parameters (bond lengths and angles) in the text.

4-Ga

Alert level B



4-In

Alert level B

PLAT230_ALERT_2_B Hirshfeld Test Diff for N1 -- C3 .. 8.9 su




Author Response: Scattering sites N1 and C3 are assigned correctly. There may be small inaccuracies in the anisotropic displacement parameters of these atoms due to the proximity of two strongly scattering indium atoms.




4. Computational details (i) Density Functional Theory (DFT) calculations

Gradient-corrected, spin-unrestricted density functional theory calculations were carried out on 2-Ga, 2-In and 2-Tl using the PBE functional,43,44 as implemented in the Amsterdam Density Functional (ADF) quantum chemistry code, versions 2012.01 and 2013.01.45, 46 Scalar relativistic effects were incorporated using the Zeroth Order Regular Approximation (ZORA) Hamiltonian. Slater Type Orbital ZORA basis sets of TZ2P quality were used for Ga, In and Tl, with all other atoms being treated with a DZP ZORA basis. For geometry optimisations, the frozen core approximation was employed: Ga(2p), In(4p), Tl(5p), 1s for all other atoms bar H. The optimisations were restricted to the C2 point group. The default SCF convergence criterion was used, together with an integration grid of 6.0 and geometry convergence criteria of 5 x 10-4 H in the energy and 5 x 10-4 H/Å in the gradients.

To calculate ESR parameters, all-electron, spin-orbit-coupled single point calculations were performed at the optimised geometries, using TZ2P basis sets on all atoms. These calculations were performed without symmetry restrictions, using an integration grid of 6.0 and the collinear approximation.

The electronic excitations of 2-Ga were calculated using the same frozen core basis sets as for the geometry optimization. The calculation was performed at the spin-orbit coupled level, without symmetry restrictions, using an integration grid of 6.0, and employing the noncollinear and Tamm-Dancoff approximations.

Prior to the present study, we were aware of a previous report of a trimetallic Pt2Tl complex, [Tl{Pt(C6F5)4}2]2–, featuring a linear Pt-Tl-Pt unit, which has been proposed by Uson and co-workers to have Tl(II) character.30 Using the same computational approach as for 2-Ga, 2-In and 2-Tl, we have optimized the geometry of this anion in D4 symmetry (using a 4d frozen core for the Pt atoms). The heavy element contributions (%) to the SOMO are Pt: 43.3 d, 10.3 s, 3.6 p and Tl: 19.3 s, strongly suggesting that [Tl{Pt(C6F5)4}2]2– should not be characterized as a Tl(II) system, in that the unpaired electron lies in an orbital of mainly platinum character.




(ii) Tables of Converged Cartesian coordinates (Å) and PBE SCF energies Supplementary Table 2: Compound 2-Ga doublet state (SCF Energy -75273.25 kJ mol-1) Ga 0.000000 0.000000 -0.750674 B -1.637890 1.163874 -1.099037 N -3.009505 0.833594 -0.755421 C -3.826649 1.936792 -1.003520 C -3.062508 2.960911 -1.466196 N -1.731211 2.544568 -1.537918 C -0.702922 3.426884 -1.993195 C -0.433942 3.518601 -3.371921 C 0.544614 4.421867 -3.796340 C 1.246959 5.199212 -2.884099 C 0.980292 5.083712 -1.524727 C 0.002094 4.204150 -1.052966 C -3.533947 -0.393090 -0.243408 C -3.491294 -0.634174 1.144690 C -4.031876 -1.831069 1.622032 C -4.594096 -2.762224 0.756124 C -4.622210 -2.509840 -0.609703 C -4.095117 -1.326677 -1.135314 B 1.637890 -1.163874 -1.099037 N 3.009505 -0.833594 -0.755421 C 3.533947 0.393090 -0.243408 C 3.491294 0.634174 1.144690 C 4.031876 1.831069 1.622032 C 4.594096 2.762224 0.756124 C 4.622210 2.509840 -0.609703 C 4.095117 1.326677 -1.135314 C 4.174636 1.055567 -2.624606 C 5.610002 0.692964 -3.031406 C 3.652226 2.228065 -3.458871 C 3.826649 -1.936792 -1.003520 C 3.062508 -2.960911 -1.466196 N 1.731211 -2.544568 -1.537918 C 0.702922 -3.426884 -1.993195 C -0.002094 -4.204150 -1.052966 C -0.980292 -5.083712 -1.524727 C -1.246959 -5.199212 -2.884099 C -0.544614 -4.421867 -3.796340 C 0.433942 -3.518601 -3.371921 C 1.192154 -2.692525 -4.391787 C 2.151302 -3.573584 -5.203022 C 0.247764 -1.914795 -5.314154 C 0.324470 -4.143056 0.426698 C 1.295175 -5.271887 0.805002 C -0.920502 -4.180189 1.315369 C -1.192154 2.692525 -4.391787 C -0.247764 1.914795 -5.314154 C -2.151302 3.573584 -5.203022 C -0.324470 4.143056 0.426698 C -1.295175 5.271887 0.805002 C 0.920502 4.180189 1.315369 C -4.174636 -1.055567 -2.624606 C -5.610002 -0.692964 -3.031406

C -3.652226 -2.228065 -3.458871 C 2.941090 -0.393915 2.114032 C 2.042711 0.224331 3.187949 C 4.088677 -1.192449 2.748967 C -2.941090 0.393915 2.114032 C -4.088677 1.192449 2.748967 C -2.042711 -0.224331 3.187949 H -4.897059 1.902855 -0.828982 H -3.359517 3.963235 -1.757316 H 0.764936 4.512059 -4.861268 H 2.011523 5.895279 -3.233325 H 1.543107 5.690185 -0.814478 H -4.012137 -2.038588 2.692680 H -5.010271 -3.691464 1.149094 H -5.060292 -3.246999 -1.284040 H 4.012137 2.038588 2.692680 H 5.010271 3.691464 1.149094 H 5.060292 3.246999 -1.284040 H 3.535195 0.185111 -2.834131 H 5.655613 0.458278 -4.106971 H 5.978199 -0.179304 -2.470474 H 6.293495 1.535193 -2.833746 H 3.626604 1.948439 -4.524449 H 4.302586 3.112880 -3.364600 H 2.637870 2.519456 -3.148745 H 4.897059 -1.902855 -0.828982 H 3.359517 -3.963235 -1.757316 H -1.543107 -5.690185 -0.814478 H -2.011523 -5.895279 -3.233325 H -0.764936 -4.512059 -4.861268 H 1.795062 -1.958462 -3.837082 H 2.728767 -2.959485 -5.912434 H 2.858249 -4.101884 -4.545186 H 1.594522 -4.330787 -5.779163 H 0.828036 -1.262845 -5.986196 H -0.440828 -1.285627 -4.730732 H -0.352359 -2.592864 -5.942517 H 0.837375 -3.186894 0.610136 H 1.548195 -5.215540 1.876014 H 2.228751 -5.207700 0.226571 H 0.836150 -6.255088 0.608302 H -0.634659 -3.994700 2.362959 H -1.414272 -5.165004 1.281733 H -1.654392 -3.417842 1.013906 H -1.795062 1.958462 -3.837082 H -0.828036 1.262845 -5.986196 H 0.440828 1.285627 -4.730732 H 0.352359 2.592864 -5.942517 H -2.728767 2.959485 -5.912434 H -1.594522 4.330787 -5.779163 H -2.858249 4.101884 -4.545186 H -0.837375 3.186894 0.610136




H -1.548195 5.215540 1.876014 H -0.836150 6.255088 0.608302 H -2.228751 5.207700 0.226571 H 0.634659 3.994700 2.362959 H 1.654392 3.417842 1.013906 H 1.414272 5.165004 1.281733 H -3.535195 -0.185111 -2.834131 H -5.655613 -0.458278 -4.106971 H -6.293495 -1.535193 -2.833746 H -5.978199 0.179304 -2.470474 H -3.626604 -1.948439 -4.524449 H -4.302586 -3.112880 -3.364600 H -2.637870 -2.519456 -3.148745 H 2.324614 -1.095136 1.532666 H 1.589755 -0.571739 3.799756 H 2.609387 0.880351 3.868373 H 1.230920 0.810324 2.730420 H 3.689599 -1.961981 3.429203 H 4.697060 -1.692003 1.979697 H 4.749943 -0.527204 3.328609 H -2.324614 1.095136 1.532666 H -3.689599 1.961981 3.429203 H -4.749943 0.527204 3.328609 H -4.697060 1.692003 1.979697 H -1.589755 0.571739 3.799756 H -1.230920 -0.810324 2.730420 H -2.609387 -0.880351 3.868373




Supplementary Table 3:Compound 2-In doublet state (SCF Energy -75219.29 kJ mol-1) In 0.000000 0.000000 0.599061 B -1.712212 1.324557 1.123918 N -3.090066 1.036877 0.786189 C -3.875754 2.162724 1.041001 C -3.079553 3.157398 1.516646 N -1.761169 2.696563 1.580485 C -0.688044 3.520578 2.038709 C 0.082847 4.230735 1.099132 C 1.139566 5.016519 1.568106 C 1.414536 5.112804 2.926744 C 0.635587 4.413184 3.841236 C -0.420550 3.602110 3.418743 C -3.609871 -0.178748 0.244266 C -4.147201 -1.143885 1.118409 C -4.608196 -2.344633 0.572218 C -4.548153 -2.578692 -0.796835 C -4.027910 -1.609953 -1.645337 C -3.548919 -0.395069 -1.146493 B 1.712212 -1.324557 1.123918 N 3.090066 -1.036877 0.786189 C 3.609871 0.178748 0.244266 C 4.147201 1.143885 1.118409 C 4.608196 2.344633 0.572218 C 4.548153 2.578692 -0.796835 C 4.027910 1.609953 -1.645337 C 3.548919 0.395069 -1.146493 C 3.046962 -0.673194 -2.098031 C 4.233053 -1.419287 -2.726555 C 2.113856 -0.119008 -3.177065 C 3.875754 -2.162724 1.041001 C 3.079553 -3.157398 1.516646 N 1.761169 -2.696563 1.580485 C 0.688044 -3.520578 2.038709 C 0.420550 -3.602110 3.418743 C -0.635587 -4.413184 3.841236 C -1.414536 -5.112804 2.926744 C -1.139566 -5.016519 1.568106 C -0.082847 -4.230735 1.099132 C 0.225571 -4.192104 -0.384531 C 0.673032 -5.572879 -0.882497 C -0.958449 -3.669668 -1.201743 C 1.254204 -2.854832 4.440776 C 2.081008 -3.828753 5.290290 C 0.392030 -1.948485 5.325615 C -0.225571 4.192104 -0.384531 C 0.958449 3.669668 -1.201743 C -0.673032 5.572879 -0.882497 C -1.254204 2.854832 4.440776 C -2.081008 3.828753 5.290290 C -0.392030 1.948485 5.325615 C -3.046962 0.673194 -2.098031 C -4.233053 1.419287 -2.726555 C -2.113856 0.119008 -3.177065 C 4.204018 0.897742 2.614694

C 2.923309 1.394865 3.297269 C 5.438867 1.517721 3.273822 C -4.204018 -0.897742 2.614694 C -5.438867 -1.517721 3.273822 C -2.923309 -1.394865 3.297269 H -4.947976 2.162465 0.870308 H -3.344856 4.166037 1.817509 H 1.752649 5.569235 0.854266 H 2.238621 5.737862 3.275434 H 0.857257 4.492076 4.906987 H -5.025666 -3.108818 1.228183 H -4.915782 -3.521740 -1.205371 H -3.991308 -1.800160 -2.718787 H 5.025666 3.108818 1.228183 H 4.915782 3.521740 -1.205371 H 3.991308 1.800160 -2.718787 H 2.471270 -1.397791 -1.503975 H 3.872947 -2.220935 -3.391279 H 4.872052 -1.870921 -1.952419 H 4.854209 -0.729058 -3.321130 H 1.700992 -0.947124 -3.774350 H 2.642596 0.554947 -3.870289 H 1.274091 0.430556 -2.725814 H 4.947976 -2.162465 0.870308 H 3.344856 -4.166037 1.817509 H -0.857257 -4.492076 4.906987 H -2.238621 -5.737862 3.275434 H -1.752649 -5.569235 0.854266 H 1.066757 -3.499213 -0.529358 H 0.960410 -5.520085 -1.944664 H 1.534832 -5.941251 -0.304925 H -0.139975 -6.310667 -0.786338 H -0.687043 -3.605494 -2.267557 H -1.269022 -2.668102 -0.867443 H -1.834110 -4.332798 -1.112729 H 1.954386 -2.211138 3.888233 H 2.721503 -3.273932 5.994359 H 2.723692 -4.460507 4.658045 H 1.425560 -4.493758 5.876165 H 1.030995 -1.363778 6.006638 H -0.307407 -2.535557 5.943056 H -0.196502 -1.249022 4.715616 H -1.066757 3.499213 -0.529358 H 0.687043 3.605494 -2.267557 H 1.269022 2.668102 -0.867443 H 1.834110 4.332798 -1.112729 H -0.960410 5.520085 -1.944664 H 0.139975 6.310667 -0.786338 H -1.534832 5.941251 -0.304925 H -1.954386 2.211138 3.888233 H -2.721503 3.273932 5.994359 H -1.425560 4.493758 5.876165 H -2.723692 4.460507 4.658045 H -1.030995 1.363778 6.006638




H 0.196502 1.249022 4.715616 H 0.307407 2.535557 5.943056 H -2.471270 1.397791 -1.503975 H -3.872947 2.220935 -3.391279 H -4.854209 0.729058 -3.321130 H -4.872052 1.870921 -1.952419 H -1.700992 0.947124 -3.774350 H -2.642596 -0.554947 -3.870289 H -1.274091 -0.430556 -2.725814 H 4.261038 -0.192024 2.764632 H 2.977930 1.225934 4.385490 H 2.777342 2.472373 3.117486 H 2.040723 0.861562 2.913551 H 5.511151 1.177619 4.318567 H 6.362808 1.230657 2.748428 H 5.378988 2.617222 3.293751 H -4.261038 0.192024 2.764632 H -5.511151 -1.177619 4.318567 H -5.378988 -2.617222 3.293751 H -6.362808 -1.230657 2.748428 H -2.977930 -1.225934 4.385490 H -2.040723 -0.861562 2.913551 H -2.777342 -2.472373 3.117486




Supplementary Table 4: Compound 2-Tl doublet state (SCF Energy -75158.94 kJ mol-1) Tl 0.000000 0.000000 1.007416 B -1.740424 1.334445 1.029942 N -3.103863 1.021494 0.663070 C -3.886417 2.168997 0.812597 C -3.101463 3.191824 1.245648 N -1.790392 2.732757 1.395017 C -0.721936 3.564820 1.849051 C 0.002835 4.326895 0.913125 C 1.044134 5.133606 1.380999 C 1.362517 5.181642 2.732569 C 0.642719 4.414874 3.641295 C -0.406083 3.592418 3.221459 C -3.628836 -0.225203 0.204515 C -4.176781 -1.126598 1.136905 C -4.684254 -2.340360 0.664341 C -4.645880 -2.655812 -0.688261 C -4.092169 -1.758156 -1.593449 C -3.571730 -0.532679 -1.168969 B 1.740424 -1.334445 1.029942 N 3.103863 -1.021494 0.663070 C 3.628836 0.225203 0.204515 C 4.176781 1.126598 1.136905 C 4.684254 2.340360 0.664341 C 4.645880 2.655812 -0.688261 C 4.092169 1.758156 -1.593449 C 3.571730 0.532679 -1.168969 C 3.003970 -0.438704 -2.184751 C 4.125473 -1.044892 -3.039048 C 1.929366 0.208634 -3.062975 C 3.886417 -2.168997 0.812597 C 3.101463 -3.191824 1.245648 N 1.790392 -2.732757 1.395017 C 0.721936 -3.564820 1.849051 C 0.406083 -3.592418 3.221459 C -0.642719 -4.414874 3.641295 C -1.362517 -5.181642 2.732569 C -1.044134 -5.133606 1.380999 C -0.002835 -4.326895 0.913125 C 0.335970 -4.309786 -0.564078 C 0.980652 -5.636103 -0.988927 C -0.885930 -3.989763 -1.430562 C 1.191270 -2.791430 4.241001 C 2.056984 -3.716499 5.106796 C 0.281770 -1.915432 5.107471 C -0.335970 4.309786 -0.564078 C 0.885930 3.989763 -1.430562 C -0.980652 5.636103 -0.988927 C -1.191270 2.791430 4.241001 C -2.056984 3.716499 5.106796 C -0.281770 1.915432 5.107471 C -3.003970 0.438704 -2.184751 C -4.125473 1.044892 -3.039048 C -1.929366 -0.208634 -3.062975

C 4.252103 0.797905 2.614545 C 3.652084 1.907170 3.483671 C 5.698367 0.495093 3.029555 C -4.252103 -0.797905 2.614545 C -5.698367 -0.495093 3.029555 C -3.652084 -1.907170 3.483671 H -4.949671 2.164984 0.595108 H -3.372423 4.219978 1.463224 H 1.617940 5.731876 0.671553 H 2.178342 5.817962 3.079824 H 0.901310 4.454049 4.700744 H -5.113352 -3.052556 1.370777 H -5.047269 -3.608109 -1.039116 H -4.061105 -2.014769 -2.653635 H 5.113352 3.052556 1.370777 H 5.047269 3.608109 -1.039116 H 4.061105 2.014769 -2.653635 H 2.526513 -1.256887 -1.626203 H 3.712964 -1.783975 -3.744358 H 4.876156 -1.545860 -2.408546 H 4.639572 -0.263452 -3.622341 H 1.484975 -0.544692 -3.732589 H 2.348103 1.010471 -3.692612 H 1.125763 0.636773 -2.445883 H 4.949671 -2.164984 0.595108 H 3.372423 -4.219978 1.463224 H -0.901310 -4.454049 4.700744 H -2.178342 -5.817962 3.079824 H -1.617940 -5.731876 0.671553 H 1.076311 -3.511853 -0.722644 H 1.263945 -5.601099 -2.053057 H 1.883284 -5.847810 -0.395353 H 0.278800 -6.474472 -0.848146 H -0.583144 -3.884222 -2.484713 H -1.370561 -3.055149 -1.110648 H -1.639468 -4.792427 -1.378009 H 1.864702 -2.122489 3.685666 H 2.660076 -3.125244 5.814297 H 2.738488 -4.316984 4.484706 H 1.428559 -4.410676 5.688458 H 0.889266 -1.290650 5.781244 H -0.392317 -2.523946 5.732043 H -0.332112 -1.250618 4.482166 H -1.076311 3.511853 -0.722644 H 0.583144 3.884222 -2.484713 H 1.370561 3.055149 -1.110648 H 1.639468 4.792427 -1.378009 H -1.263945 5.601099 -2.053057 H -0.278800 6.474472 -0.848146 H -1.883284 5.847810 -0.395353 H -1.864702 2.122489 3.685666 H -2.660076 3.125244 5.814297 H -1.428559 4.410676 5.688458 H -2.738488 4.316984 4.484706




H -0.889266 1.290650 5.781244 H 0.332112 1.250618 4.482166 H 0.392317 2.523946 5.732043 H -2.526513 1.256887 -1.626203 H -3.712964 1.783975 -3.744358 H -4.639572 0.263452 -3.622341 H -4.876156 1.545860 -2.408546 H -1.484975 0.544692 -3.732589 H -2.348103 -1.010471 -3.692612 H -1.125763 -0.636773 -2.445883 H 3.658526 -0.113497 2.779103 H 3.626709 1.587202 4.537721 H 4.250907 2.830941 3.430079 H 2.627303 2.153836 3.168100 H 5.741444 0.216430 4.094624 H 6.117777 -0.332013 2.436435 H 6.340258 1.378729 2.879386 H -3.658526 0.113497 2.779103 H -5.741444 -0.216430 4.094624 H -6.340258 -1.378729 2.879386 H -6.117777 0.332013 2.436435 H -3.626709 -1.587202 4.537721 H -2.627303 -2.153836 3.168100 H -4.250907 -2.830941 3.430079




Supplementary Table 5: [Tl{Pt(C6F5)4}2]-2 doublet state (SCF Energy -57063.15 kJ mol-1) Tl 0.000000 0.000000 0.000000 Pt 0.000000 0.000000 -2.775242 Pt 0.000000 0.000000 2.775242 C -2.058139 -0.338519 -2.885657 C -0.338519 2.058139 -2.885657 C 0.338519 -2.058139 -2.885657 C 2.058139 0.338519 -2.885657 C -2.058139 0.338519 2.885657 C -0.338519 -2.058139 2.885657 C 0.338519 2.058139 2.885657 C 2.058139 -0.338519 2.885657 C -3.002184 0.229257 -2.039221 C -4.371817 0.029352 -2.164560 C -2.585774 -1.120731 -3.910312 C -3.944711 -1.356459 -4.068391 C -4.844672 -0.780578 -3.185116 F -2.615712 1.041804 -1.012689 F -5.250914 0.616141 -1.321630 F -1.772811 -1.669402 -4.854194 F -4.411919 -2.127247 -5.084976 F -6.175619 -0.995229 -3.328484 C 0.229257 3.002184 -2.039221 C 0.029352 4.371817 -2.164560 C -1.120731 2.585774 -3.910312 C -1.356459 3.944711 -4.068391 C -0.780578 4.844672 -3.185116 F 1.041804 2.615712 -1.012689 F 0.616141 5.250914 -1.321630 F -1.669402 1.772811 -4.854194 F -2.127247 4.411919 -5.084976 F -0.995229 6.175619 -3.328484 C -0.229257 -3.002184 -2.039221 C -0.029352 -4.371817 -2.164560 C 1.120731 -2.585774 -3.910312 C 1.356459 -3.944711 -4.068391 C 0.780578 -4.844672 -3.185116 F -1.041804 -2.615712 -1.012689 F -0.616141 -5.250914 -1.321630 F 1.669402 -1.772811 -4.854194 F 2.127247 -4.411919 -5.084976 F 0.995229 -6.175619 -3.328484 C 3.002184 -0.229257 -2.039221 C 4.371817 -0.029352 -2.164560 C 2.585774 1.120731 -3.910312 C 3.944711 1.356459 -4.068391 C 4.844672 0.780578 -3.185116 F 2.615712 -1.041804 -1.012689 F 5.250914 -0.616141 -1.321630 F 1.772811 1.669402 -4.854194 F 4.411919 2.127247 -5.084976 F 6.175619 0.995229 -3.328484 C -3.002184 -0.229257 2.039221 C -4.371817 -0.029352 2.164560 C -2.585774 1.120731 3.910312

C -3.944711 1.356459 4.068391 C -4.844672 0.780578 3.185116 F -2.615712 -1.041804 1.012689 F -5.250914 -0.616141 1.321630 F -1.772811 1.669402 4.854194 F -4.411919 2.127247 5.084976 F -6.175619 0.995229 3.328484 C 0.229257 -3.002184 2.039221 C 0.029352 -4.371817 2.164560 C -1.120731 -2.585774 3.910312 C -1.356459 -3.944711 4.068391 C -0.780578 -4.844672 3.185116 F 1.041804 -2.615712 1.012689 F 0.616141 -5.250914 1.321630 F -1.669402 -1.772811 4.854194 F -2.127247 -4.411919 5.084976 F -0.995229 -6.175619 3.328484 C -0.229257 3.002184 2.039221 C -0.029352 4.371817 2.164560 C 1.120731 2.585774 3.910312 C 1.356459 3.944711 4.068391 C 0.780578 4.844672 3.185116 F -1.041804 2.615712 1.012689 F -0.616141 5.250914 1.321630 F 1.669402 1.772811 4.854194 F 2.127247 4.411919 5.084976 F 0.995229 6.175619 3.328484 C 3.002184 0.229257 2.039221 C 4.371817 0.029352 2.164560 C 2.585774 -1.120731 3.910312 C 3.944711 -1.356459 4.068391 C 4.844672 -0.780578 3.185116 F 2.615712 1.041804 1.012689 F 5.250914 0.616141 1.321630 F 1.772811 -1.669402 4.854194 F 4.411919 -2.127247 5.084976 F 6.175619 -0.995229 3.328484




5. EPR spectroscopy (ii) Experimental

X-band CW EPR experiments were performed on a Bruker BioSpin GmbH EMX spectrometer equipped with a high sensitivity Bruker probehead, and pulse EPR experiments were carried out at X- and W-band on a Bruker E680 spectrometer. Both instruments were equipped with Oxford Instruments helium-flow cryostats. The X-band CW EPR spectra were recorded at 10 K using a modulation frequency of 100 kHz, modulation amplitudes of 0.2 mT (2-Ga, 2-In) and 0.5 mT (2-Tl), microwave powers for 2-Ga and 2-In of 0.079 mW (34 dB, 200 mW source) and for 2-Tl 1.987 mW (20 dB). At W-band the field-sweep EPR spectra were recorded in pulse mode by integrating the echo (fwhh) from the two-pulse echo sequence π/2 - τ - π - τ - echo, with tπ/2 = 32 ns, tπ = 62 ns, and τ = 200 ns. A two-step phase cycle was used, (+,+) − (−,+). Measurements were made on 2-Ga, 2-In and 2-Tl at 10, 12.5, and 4.5 K, respectively. At X-band the 2-Tl echo-detected EPR spectrum was measured with the same pulse timings and temperature as at W-band. At X-band Hyperfine sublevel correlation (HYSCORE)47,48 experiments employed the pulse sequence π/2 - τ - π/2- t1- π - t2- π/2 - τ -echo, using the following parameters: mw pulses of lengths tπ/2 = 16 ns, starting times t1 = t2 = 96 ns, and time increments of Δt = 20 ns (data matrix 128×128). Matched HYSCORE data were collected with the sequence π/2 - τ - P- t1- π - t2- P - τ -echo, where pulse P is applied for 32 ns with B1 ≅ 31.25 MHz (tuned for tπ =16 ns). Both sequences used an eight-step phase cycle to remove unwanted echoes. The HYSCORE data were processed with MATLAB 7.0 (The MathWorks, Inc.). The time traces were baseline corrected with an exponential, apodized with a Gaussian window, and zero filled. After a two-dimensional Fourier transformation, absolute-value spectra were calculated. X-band Davies ENDOR were recorded at 10 K for 2-Ga and 2-In using the microwave pulse sequence π - T - π/2 - τ - π - τ - echo with mw pulses of lengths tπ/2 = 32 ns and tπ = 64 ns, with τ = 116 ns. During time T a 9 µs radio frequency (rf) pulse was applied stochastically using 60% gain of a 500 W Applied Engineering rf amplifier. For 2-Ga an experiment with weak mw pulses was additionally performed to enhance signals from weakly coupled protons relative to the strong coupled boron nuclei. This experiment employed mw pulses of lengths tπ/2 = 120 ns and tπ = 240 ns, with τ = 460 ns. To verify the g-values of 2-Tl (as determined by simulation of the field-sweep EPR spectra) an electron-spin echo nutation experiment49 at 4.5 K was employed using the sequence P - τ - π - τ - echo with a mw pulse of length tπ = 240 ns with τ = 440 ns. The pulse P was incremented from 4 ns to 1024 ns in steps of ΔP = 4 ns. The field strength B1 of pulse P was referenced against an organic radical with g = 2, and both 2-Tl and the reference organic radical sample were measured under identical conditions (resonator coupling and input mw power). The CW EPR, ENDOR and HYSCORE spectra were simulated with the program EasySpin.50 HYSCORE cross-peak positions (frequencies) were matched to the experimental positions by calculating cross-peaks frequencies by diagonalisation of a spin Hamiltonian with nuclear Zeeman, hyperfine and nuclear quadrupole interactions (no intensity calculation).




(ii) Spin Density Calculations Spin densities in the s- and p-type orbital of nitrogen and boron contributing to the SOMO were estimated from the isotropic (aiso) and anisotropic (T) hyperfine couplings, where (A1, A2, A3) = aiso + ( −T1, −T2, T1+T2). The spin density in the s-type orbital is ρs = aiso / a0, where a0 is the coupling for an unpaired electron in an atomic 2s-orbital of 14N (a0 = 1809 MHz) or 11B (a0 = 2544 MHz). For the p-type orbital spin density, ρp= T / b0, where b0 is the coupling for an un-paired electron in an atomic 2p-orbital of 14N (b0 = 55.5 MHz) or 11B (b0 = 63.6 MHz).51 To allow a T value to be determined for the approximately axial experimental boron hyperfine coup-lings, an average was value taken, T = (T1 + T2)/2. An axial interaction has values –T, –T, 2T.



SUPPLEMENTARY INFORMATIONDOI: 10.1038/NCHEM.1870 S28

Supplementary Table 6: Experimental and DFT (in italics/parentheses) EPR parameters for 2-Ga, 2-In and 2-Tl. Listed are the principal g-values gi, linewidths at X- and W-band Li, principal values Ai and the isotropic aiso and anisotropic Ti hyperfine couplings (MHz), the spin densities in s-type ρs and p-type ρp orbitals and their sum ρ, and the nuclear quadrupole coupling parameters κ (MHz) and η Complex g1, g2, g3 X-band L1, L2, L3 W-band L1, L2, L3

2-Ga 1.881, 1.998, 2.014 (1.8760, 1.9960, 2.0113) e

150, 150, 250 325, 325, 1500

Nuclei A1, A2, A3 aiso c −T1, −T2, T1+T2

c ρ s ρp ρ κ h η 69Ga (I=3/2)

444, 1032, 533 (29,526, 87)

670 (214)

−226,362,−137 (−185,312,−127)

- (0.048)

- (0.683)

0.78 b (0.734)

- (12.7)

- (0.85)

11B g (I=3/2)

20,22,34 (4.4,5.5,13.1)

25.3 (7.7)

−5.3,−3.3,8.7 (−3.3,−2.2,5.4)

0.01 (0.003)

0.068 (0.032)

0.078 (0.039)

<0.2 (0.13)

- (0.36)

14NA g

14NB (I=1)

4.5,4.5,7.0 1.8,1.8,3.5 (1.5, 1.7, 7.6) (−1.1,−0.8,5.0)

5.3 2.4 (3.6) (1.0)

−0.8,−0.8,1.7 −0.6,−0.6,1.1 (−2.1,−1.9,4.0) (−2.1,−1.8,4.0)

0.003 0.001 (0.002) (0.002)

0.015 0.010 (0.027) (0.027)

0.018 0.012 (0.029) (0.029)

−0.7 “ (−0.69) (−0.69)

0.8 “ (0.78) (0.78)

2-In g1, g2, g3 X-band L1, L2, L3 W-band L1, L2, L3

1.719, 1.954, 1.999 (1.7338, 1.9689, 2.0125) e

500, 500, 900 900, 1500, 1500


c ρ s ρp ρ κ h η 115In (I=9/2)

913, 1936, 793 (237,1266,431)

1214 (645)

(-301,722,-421) (−408,621,−214)

- (0.071)

- (0.644)

0.75 b (0.727)

- (7.8)

- (0.8)

11B g (I=3/2)

25,27,42 (31,31.9,42)

31.3 (35.0)

−6.3,−4.3,10.7 (−4.0,−3.1,7.0)

0.012 (0.014)

0.084 (0.044)

0.096 (0.06)

<0.2 (0.14)

- (0.28)

14N g (I=1)

2.5, 2.5,4.5 (2.3, 2.6, 6.6) (−1.0,−0.7,3.4)

3.2 (3.8) (0.6)

−0.7,−0.7,1.3 (−1.5,−1.2,2.8) (−1.6,−1.3,2.8)

0.002 (0.002) (0.001)

0.012 (0.019) (0.017)

0.014 (0.020)

−0.7 (−0.69) (−0.69)

0.8 (0.83) (0.86)

2-Tl g1, g2, g3 X-band L1, L2, L3 W-band L1, L2, L3

0.6, 0.7, 1.23 f (1.0047, 1.4381, 1.697) e

800, 800, 800 1500, 1500, 1500


c ρ s ρp ρ κ h η 205Tl (I=1/2)

−8000,10300,−8100 d (−8971,4726,−4353)

-1933 (−2866)

−6067,12233,−6167 (−6105,7592,−1487)

- (0.015)

- (0.708)

- (0.723)

- -

11B (I=3/2)

ND a (−23.7,−13.9,−9.5)

ND a (−15.7)

ND a (−8.0,1.8,6.2)

ND a (-0.011)

ND a

(0.043) ND a (0.036)

- (0.12)

- (0.01)

14N g (I=1)

3.5,3.5,6.5 (0.6,2.3,5.4) (−2.3,−0.5,5.1)

4.5 (2.8) (0.8)

−1.0,−1.0,2 (−2.2,−0.5,2.6) (−3.1,−1.3,4.3)

0.003 (0.002) (0.002)

0.018 (0.027) (0.027)

0.021 (0.029) (0.029)

−0.7 (−0.69) (−0.69)

0.8 (0.82) (0.82)

a) ND – no measurement, not determined; b) spin density estimated by the difference, ρM = 1 – (2ρB + 4ρN); c) experimental aiso and Ti values were calculated as: (A1, A2, A3) = aiso + ( −T1, −T2, T1+T2); d) the sign of the experimental Tl hyperfine values were assigned according to the DFT data where the middle g-value is assigned with a positive hyperfine coupling and the largest and smallest g-values are assigned with negative hyperfine couplings. The size of the Tl hyperfine coupling can be appreciated by considering the case at X-band at g=1.23 (B0 ≅ 550 mT); this feature would be split by a Tl hyperfine coupling of 9467 MHz (≡ 550 mT at g=1.23) into a doublet with one peak of the doublet at approximately B0 = 0, as observed in the X-band CW EPR spectrum; e) In the EPR simulations and the DFT data (to a good approximation): g1 || A1, g2 || A2, g3 || A3. In the DFT calculation the g1 axis points ca. along the B-B vector, axis g2 points ca. at right angles to the B-B vector and in the mean plane going through the two B(NDippCH)2 moieties, and g3 is at right-angles to the B-B vector and the mean plane going through the two B(NDippCH)2 moieties; f) the largest g-value of 1.23 is defined from the low-field edge of the W-band echo-detected spectrum and is accurate. The lowest value of 0.6 was determined at X-band largely from the echo-detected EPR spectrum which exhibits a large echo at 1.5 T (maximum field obtainable with our spectrometer). The middle g-value is harder to determine and carries a large error; g) The orientations for the hyperfine and nuclear quadrupole axes from the DFT calculations were used for simulations of the ENDOR and HYSCORE data; h) Nuclear quadrupole interactions κ = (e2qQ/2h)/(2Ι (2Ι− 1)) [MHz] and asymmetry parameters η = (Qx − Qy)/Qz with Qx = −κ(1 − η), Qy = −κ (1 + η), and Qz = 2κ.




Supplementary Figure 4: X-band nutation experiment on 2-Tl to verify the g-values that were determined by field-sweep EPR experiments at X- and W-band. Blue trace: 2-Tl, B0 = 3 mT; red trace: 2-Tl complex, B0 = 1300 mT; black: organic radical reference sample with a known g-value of g = 2. The nutation frequency, ν, of the magnetisation is proportional to gB1 i.e.ν ∝ gB1 where g is the g-value and B1 is the mw excitation field strength. For 2-Tl measured at B0 = 3mT (blue curve), νTl ≅ 1/220 ns = 4.55 MHz, and at B0 = 1300 mT (red), νTl ≅ 1/250 ns = 4.00 MHz. For the reference sample with g = 2, νreference =1/110 ns = 9.09 MHz. The excitation field B1 used was the same for both 2-Tl and the reference sample; thus νTl / νreference = gTl / greference. This yields gTl(3 mT) = 1.0, and gTl(1300 mT) = 0.88, consistent with the principal g-values derived from simulation of the field-sweep EPR spectra, g= (0.6, 0.7, 1.23).




Supplementary Figure 5: . (panels a and b) X-band (9.4512 GHz) matched HYSCORE spectra of 2-Ga measured at 10 K. (panel a) B0 = 321 mT, τ = 140 ns; (panel b) B0 = 387.5 mT, τ = 128 ns. Two distinct nitrogen couplings are observed, as indicated by the ‘A’ and ‘B’ superscript on the labels identifying cross-peaks with single-quantum (sq) and double-quantum (dq) transitions. At both measurement fields the nitrogens are predominately in the strong coupling case, A(14N) > 2ν(14N) ∼ 2.3 MHz, and thus intense sq and dq cross-peaks are observed in the (−,+) quadrant. Initial values for the hyperfine couplings can be read of the graph as indicated for nitrogen A. Insets: echo-detected EPR spectrum with the position of the HYSCORE measurement indicated by the vertical line. (panels c and d) X-band (9.424 GHz) matched HYSCORE spectra of 2-In measured at 7.5 K. (panel c) B0 = 260 mT, τ = 108 ns; (panel d) B0 = 444 mT, τ = 100 ns. Labels identifying cross-peaks with single-quantum (sq) and double quantum (dq) transitions are indicated. In the measurement at B0 = 444 mT there are cross-peaks [e.g. (dq,sq)] in both quadrants, indicating the hyperfine coupling is close to the exact cancellation condition where

a b

c d

e




the nuclear Zeeman interaction cancels the hyperfine interaction in one of the electron spin manifolds, A(14N) ∼ 2ν(14N) = 2.7 MHz. The contributing orientations at this field position thus have hyperfine couplings around 2.7 MHz. Insets: echo-detected EPR spectrum with the position of the HYSCORE measurement indicated by the vertical line. Note the low field part of the spectrum is not detected (no echo) because of very short relaxation times (<100 ns). (panel e) X-band (9.4535 GHz) HYSCORE spectrum of 2-Tl measured at 4.5K, B0 = 1000 mT, τ = 140 ns. At this field the nitrogen hyperfine coupling is predominately in the weak coupling regime, A(14N) < 2ν(14N) = 6.16 MHz, and thus strong cross-peaks are observed in the (+,+) quadrant. The (dq,sq) cross-peaks near the anti-diagonal at 2ν(14N) are split approximately by the hyperfine coupling. The orientation of these cross-peaks is sensitive to the anisotropy of the hyperfine and nuclear quadrupole couplings, allowing their values to be estimated. Inset: echo-detected EPR spectrum with the position of the HYSCORE measurement indicated by the vertical line.




Supplementary Figure 6: panel a) X-band Davies-ENDOR of 2-Ga measured at 10 K at the field positions indicated by the thick vertical lines in the echo-detected EPR spectrum shown at the top. Black traces: experimental with tπ = 64 ns; blue traces: experimental with tπ = 240 ns (selective inversion pulse to enhance signals from weakly coupled 1H nuclei); red traces: simulation of 11B signals using the parameters listed in Extended Data Table 2. The 14N couplings, characterized via HYSCORE spectroscopy, are predicted to be below 5 MHz and are too weak to be identified in the spectra (simulations thus not shown). Note that the Larmor frequency for 11B at these fields is ca. 4.8 MHz, and given the large hyperfine coupling and therefore large ENDOR hyperfine enhancement effect, it is straightforward to apply a nominal rf π-pulse for 11B that has a short length and minimal rf input power (i.e. with a 9 µs pulse and 300 W input rf power the experiment will be sensitive to strongly coupled 11B nuclei). (panel b) X-band Davies-ENDOR of 2-In measured at 10 K at the field 430 mT. Black trace: experimental with tπ = 64 ns; red trace: simulation of 11B signals using the parameters listed in Extended Data Table 2. The 14N couplings, characterized via HYSCORE spectroscopy, are predicted to be below 5 MHz and are too weak to be identified in the spectrum (simulations thus not shown). Note that the Larmor frequency for 11B at this field is 5.9 MHz, and given the large hyperfine coupling and therefore large ENDOR hyperfine enhancement effect, it is straightforward to apply a nominal rf π-pulse for 11B that has a short length and minimal rf input power (i.e. with a 9 µs pulse and 300 W input rf power the experiment will be sensitive to strongly coupled 11B nuclei).

a b




6. Cyclic voltammetry measurements

Supplementary Figure 7: Cyclic voltammogram of 2-Tl in tetrahydrofuran. Electrochemical measurements were carried out on a PARAMETEK VersaSTAT3 potentiostat under a nitrogen atmosphere within a Saffron Omega Scientific glove-box. Measurements were carried out using a supporting electrolyte of 0.2 M [nBu4N][PF6] electrolyte in dry/degassed tetrahydrofuran. The scan rate was 2 V s-1. Cyclic voltammetry measurements were recorded with a silver quasi-reference electrode, a platinum working electrode and a platinum wire auxiliary electrode. The results are referenced against ferrocene/ferrocenium.

TlII → TlIII

TlI → TlII




7. UV/Vis spectroscopy (i) Experimental measurements

Supplementary Figure 8: UV/Visible spectra of 2-Ga (panel a), 2-In (panel b) and 2-Tl (panel c) in hexane (at concentrations of 1 mM, 0.2 mM and 0.2 mM respectively). The feature marked (*) is an instrumental artefact. The extinction coefficients associated with the features in these spctra are as follows: 2-Ga: λ = 611 nm, ε = 30 mol-1 dm3 cm-1; λ = 362 nm ε = 1640 mol-1 dm3 cm-1; λ = 309 nm, ε = 1850 mol-1 dm3 cm-1; 2-In: λ = 369 nm, ε = 8300 mol-1 dm3 cm-1; λ = 322 nm ε = 9900 mol-1 dm3 cm-1; 2-Tl: λ = 471 nm, ε = 220 mol-1 dm3 cm-1; λ = 408 nm ε = 410 mol-

1 dm3 cm-1; λ = 354 nm, ε = 7500 mol-1 dm3 cm-1; λ = 310 nm, ε = 7000 mol-1 dm3 cm-1.

a

b c




(ii) TD-DFT

Supplementary Figure 9: Calculated UV/Vis spectrum for 2-Ga.




Supplementary Table 7: Transition number, energy (eV and nm), oscillator strength and orbital composition relating to the calculated UV/Vis spectrum of 2-Ga. Number eV nm f Transition orbitals for all transitions with f

over 0.001 (min 10% contribution) 1 0.24036 5158.928274 3.23E-07 2 0.70242 1765.325589 4.55E-03 89, 319->320; 11, 319->321 3 0.71426 1736.062498 9.97E-07 4 1.54936 800.330459 2.73E-06 5 1.55517 797.3404837 1.05E-03 100, 319->323 6 1.56356 793.0619867 3.49E-06 7 1.57349 788.0571214 3.20E-03 63, 319->325; 36, 319->327 8 1.57729 786.1585377 6.42E-09 9 1.58651 781.5897788 7.97E-03 64, 319->327; 35, 319->325 10 1.59097 779.3987316 5.83E-06 11 1.59419 777.8244751 1.15E-04 12 1.64099 755.6414116 1.86E-10 13 1.64937 751.8022033 7.02E-03 99, 319->331 14 1.6793 738.402906 4.93E-06 15 1.68215 737.1518592 8.62E-05 16 1.69948 729.6349472 7.26E-07 17 1.71359 723.6270053 3.99E-08 18 1.71544 722.8466166 4.22E-05 19 1.72024 720.8296517 5.03E-03 98, 319->336 20 2.72641 454.8105384 2.40E-04 21 2.74347 451.9823435 4.53E-05 22 2.78635 445.0266478 2.87E-04 23 2.79355 443.8796513 4.68E-02 95, 319->339 24 2.81533 440.4457026 9.53E-04 25 2.82633 438.7314999 5.96E-05 26 2.8562 434.1432673 9.99E-03 70, 318->321; 24, 315->320 27 2.87344 431.5385044 1.05E-06 28 2.87613 431.1348931 8.02E-06 29 2.90351 427.0693058 4.14E-04 30 2.91201 425.8227135 5.51E-05 31 2.91363 425.5859529 1.04E-02 87, 319->343; 11, 319->341 32 2.91413 425.5129318 2.99E-04 33 2.97818 416.3616706 5.80E-04 34 2.99513 414.0054021 1.18E-04 35 3.05538 405.8414993 1.26E-03 92, 317->322 36 3.07858 402.7831013 9.14E-02 48, 319->341; 41, 316->322 37 3.10871 398.8792779 3.04E-03 31, 318->322; 31, 319->347; 23, 316->321 38 3.16734 391.495703 1.32E-06 39 3.18321 389.5438881 2.69E-06 40 3.18693 389.0891861 4.58E-05




41 3.19439 388.180529 4.54E-03 99, 319->348 42 3.23037 383.8569576 0.2199 43, 316->322; 20, 319->341; 14, 315->320;

10, 318->321 43 3.27564 378.5519776 3.82E-04 44 3.34607 370.5839985 1.77E-07 45 3.3593 369.12452 3.03E-02 95, 319->351 46 3.45303 359.1049021 2.20E-04 47 3.49373 354.9215309 1.91E-03 85, 319->353 48 3.49867 354.420394 1.03E-05 49 3.50926 353.3508489 6.36E-04 50 3.62257 342.2984235 8.25E-08




Supplementary Table 8: Assignment of bands in the calculated UV/Vis spectrum of 2-Ga. (experimental data in bold). All MOs belong to the a1/2 irreducible representation. The SOMO is MO 319.

Energy/eV (nm) f Transition MOs Initial MO Final MO 1.587 (782) 2.03 (611)

7.97 x 10–3 64% 319→327

35% 319→325





4.68 x 10–2 95% 319→339





9.14 x 10–2 48% 319→341

41% 316→322




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DOI: 10.1038/NCHEM - Nature · NATURE CHEMISTRY | 3 DOI: 10.1038/NCHEM.1870 SUPPLEMENTARY INFORMATION S3 1. Syntheses (i) General methods and instrumentation