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aA. N. Nesmeyanov Institute of Organoele

Sciences, Vavilov str. 28, 119991 Moscow, RbL. Ya. Karpov Institute of Physical Chem

Moscow, Russia

† Electronic supplementary information (of 1, 2 and in presence of macrocycles inles (CIF) for the complexes {[(CuL)3]$CCDC 948156–948158. For ESI and crelectronic format see DOI: 10.1039/c3ra47

Cite this: RSC Adv., 2014, 4, 8350

Received 26th November 2013Accepted 13th January 2014

DOI: 10.1039/c3ra47040g

www.rsc.org/advances

8350 | RSC Adv., 2014, 4, 8350–8359

Role of basic sites of substituted ferrocenesin interaction with the trinuclear 3,5-bis(trifluoromethyl)pyrazolates: thermodynamicsand structure of complexes†

Alexey A. Titov,a Oleg A. Filippov,a Ekaterina A. Guseva,a Alexander F. Smol'yakov,a

Fedor M. Dolgushin,a Lina M. Epstein,a Vitaly K. Belskyb and Elena S. Shubina*a

Formation of complexes of the macrocycles (ML)3, where L ¼ 3,5-(CF3)2Pz ¼ 3,5-bis(trifluoromethyl)

pyrazolate, M ¼ Cu and Ag, and the acylferrocenes FcC(O)CH2R (Fc ¼ (C5H5)Fe(C5H4); R ¼ H (1), Ph (2))

was studied by means of variable temperature IR, UV-vis, NMR spectroscopy. The sole site of

coordination in solution is the oxygen atom of the CO group. The complex composition (1 : 1) and

thermodynamic parameters in hexane solution were determined, the formation constants and the

enthalpies decreasing from 1 to 2 and from Ag to the Cu macrocycle. The same coordination site

featuring triple coordination of oxygen to all metal atoms of a macrocycle was found in the solid state

by single crystal X-ray diffraction. There are no shortened contacts of the metal in the macrocycles with

p-electron system of the ferrocene's cyclopentadienyl ligands in all complexes. The complexes of (ML)3with 1 have 1 : 2 composition and bipyramidal structure whereas 2 forms the 1 : 1 complex with (AgL)3.

The latter is packed in the infinite stacks involving additional contacts with Ph groups.

Introduction

The uoro-substituted pyrazolates or imidazoles (ML)3, M¼ Cu,Ag, Au, were actively studied as compounds possessing signi-cant luminescent and p-acidic properties.1–3 The ability to formcomplexes with organic arenes as bases was shown.3–5 Theseadducts form structures of the general formula {[(ML)3]m$Arn}N(m, n ¼ 1, 2).4,5 In our previous work we have shown that in thecomplexes of (ML)3 (M ¼ Cu, Ag) with iron compounds such as(COT)Fe(CO)3 (COT ¼ cyclooctatetraene), Cp2Fe, Fe(CO)5 insolid state and in solution only p-electron system (COT or Cpligand) is involved in the complex formation.6 There is nocoordination of the macrocycles with (Fe)–CO group of (COT)Fe(CO)3 as well as no complexation was found with Fe(CO)5. Atthe same time in the solid phase ferrocene behaves similar tomesitylene4 and forms innite stacks {[(ML)3]$[Cp2Fe]}N withmacrocycles.6 Our recent study of (ML)3 interaction with buta-none-2 as the example of aliphatic ketones and benzophenone

ment Compounds, Russian Academy of

ussia

istry, Vorontsovo Pole St. 10, 103064,

ESI) available: The IR and NMR spectrahexane, crystallographic information

2[1]}, {[(AgL)3]$2[1]} and {[(AgL)3]$[2]}.ystallographic data in CIF or other040g

as a representative of aromatic ketones evidenced that theoxygen atom of CO group is a sole site of coordination for allcomplexes in solution.7 X-Ray data demonstrated various typesof composition and structure in the solid state for thecomplexes of (ML)3 with Ph2CO among which there are sand-wiches with additional contacts to phenyl ring,6 but the mainsite of coordination is again the oxygen atom.

The aim of this work was to reveal the site competition in thesubstituted ferrocenes (acetylferrocene (1) and (phenylacetyl)-ferrocene (2)) interacting with copper(I) and silver(I) trinuclearpyrazolates in solution and in the solid state.

ExperimentalGeneral

Themacrocycles ([3,5-(CF3)2Pz]Ag)3 and ([3,5-(CF3)2Pz]Cu)3 weresynthesized according to the published procedure.8 IR spectraof the compounds in CH2Cl2 and hexane solutions weremeasured on Nicolet 6700 FTIR spectrometer in CaF2 cells (d ¼0.04–0.4 cm), using a home modied cryostat (Carl Zeiss Jena)for variable temperature measurements. The accuracy of thetemperature adjustment was �1 K. IR studies in the n(CO)region (1690–1610 cm�1) were carried out at various concen-trations (10�3 to 10�2 M) and ratios of the reagents. Thecomposition of the complexes in solution was determined bythe saturation and the continuous variation (Job) methods.Room and low temperature NMR measurements were carried

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out on Bruker Avance 600 spectrometer operating at600.22 MHz (1H) and 150.93 MHz (13C{1H}). The temperaturewas controlled using Bruker BVT-3000 accessory; the accuracyof the temperature adjustment and stability was �1 K. Thespectra were calibrated with the residual solvent resonancerelative to TMS (1H, 13C). UV-vis spectra were measured onCary50 spectrometer using a Carl Zeiss Jena cryostat for variabletemperature measurements.

Isolation of crystals

{[([3,5-(CF3)2Pz]Cu)3]$2[FcC(O)CH3]}. The macrocycle ([3,5-(CF3)2Pz]Cu)3 (4.8 mg, 0.006 mmol) was added to a solution ofFeC10H9C(O)CH3 (1.4 mg, 0.006 mmol) in hexane. Slow solventevaporation at 5 �C gave orange-red crystals. Anal. calc. (%) forC39H27Cu3F18Fe2N6O2: C 37.30, H 2.17, N 6.69, found: C 37.38,H 2.05, N 6.62. IR (Nujol, cm�1): 3139 (CH (CuL)3), 1610(CObond), 1540, 1508, 1457.

{[([3,5-(CF3)2Pz]Ag)3]$2[FcC(O)CH3]}. The macrocycle ([3,5-(CF3)2Pz]Ag)3 (5.6 mg, 0.006 mmol) was added to a solution ofFeC10H9C(O)CH3 (1.4 mg, 0.006 mmol) in hexane. Slow solventevaporation at 5 �C gave orange-red crystals. Anal. calc. (%) forC39H27Ag3F18Fe2N6O2: C 33.73, H 1.96, N 6.05, found: C 33.78, H2.08, N 5.98. IR (Nujol, cm�1): 3138 (CH (AgL)3), 1615 (CObond),1547, 1532, 1448.

{[([3,5-(CF3)2Pz]Ag)3]$[FcC(O)CH2Ph]}. The macrocycle ([3,5-(CF3)2Pz]Ag)3 (5.6 mg, 0.006 mmol) was added to a solution ofFeC10H9C(O)CH2Ph (1.8 mg, 0.006 mmol) in hexane. Slowsolvent evaporation at 5 �C gave orange-red crystals. Anal. calc.(%) for C33H19Ag3F18FeN6O: C 32.04, H 1.55, N 6.79, found: C

Table 1 Crystal data, data collection and structure refinement paramete(CF3)2Pz]Ag)3]$[2]}

Compound {[([3,5-(CF3)2Pz]Cu)3]$2[1]}

Molecular formula C39H27F18N6O2Fe2Cu3Formula weight 1255.99Dimension, mm 0.24 � 0.21 � 0.09Crystal system OrthorhombicSpace group Pbcaa, A 11.5920(11)b, A 16.9249(16)c, A 44.395(4)a, deg. 90.00b, deg. 90.00g, deg. 90.00V, A3 8710.0(14)Z 8rcalc, g cm�3 1.916Linear absorp. (m), cm�1 22.13Tmin/Tmax 0.642/0.8262qmax, deg. 54No. unique re. (Rint) 9481 (0.0892)No. obs. re. (I > 2s(I)) 6653No. parameters 642R1 (on F for obs. re.)a 0.0493wR2 (on F2 for all re.)b 0.1103GOOF 1.052

a R1 ¼P

rrFor � rFcrr/P

rFor.b wR2 ¼ {

P[w(Fo

2 � Fc2)2]/

Pw(Fo

2)2}1/2.

This journal is © The Royal Society of Chemistry 2014

32.12, H 1.45, N 6.74. IR (Nujol, cm�1): 3138 (CH (AgL)3), 1627(CObond), 1534, 1503, 1453.

The crystals obtained this way were suitable for X-rayanalysis.

X-ray studies

Single-crystal X-ray diffraction study was carried out with aBruker SMART APEX II diffractometer (graphite mono-chromated Mo-Ka radiation, l ¼ 0.71073 A, u-scan technique, T¼ 100 K). The APEX II soware9 was used for collecting framesof data, indexing reections, determination of lattice constants,integration of intensities of reections, scaling and absorptioncorrection, and SHELXTL10 was used for space group andstructure determination, renements, graphics, and structurereporting. The structures were solved by direct methods andrened by the full-matrix least-squares technique against F2

with the anisotropic thermal parameters for all non-hydrogenatoms. The H(C) atoms were placed geometrically and includedin the structure factors calculation in the riding motionapproximation. In the crystal of {[([3,5-(CF3)2Pz]Cu)3]$2[1]}, oneof six CF3 groups is disordered over two positions with 0.65/0.35occupancies. The principal experimental and crystallographicparameters are listed in Table 1.

Physical measurements

Steady-state luminescence and excitation spectra were recordedon Fluorolog FL 3-22 Horiba-Jobin-Yvon photon countingemission spectrometer equipped with a 450 W xenon sourceand double monochromators for excitation and emission. The

rs for {[([3,5-(CF3)2Pz]Cu)3]$2[1]}, {[([3,5-(CF3)2Pz]Ag)3]$2[1]} and {[([3,5-

{[([3,5-(CF3)2Pz]Ag)3]$2[1]} {[([3,5-(CF3)2Pz]Ag)3]$[2]}

C39H27F18N6O2Fe2Ag3 C33H19F18N6OFeAg31388.98 1237.000.22 � 0.06 � 0.05 0.17 � 0.14 � 0.08Monoclinic OrthorhombicC2/c Pna2119.8409(8) 14.9390(5)13.5269(5) 24.6385(8)17.6393(7) 10.4127(3)90.00 90.00108.393(1) 90.0090.00 90.004492.3(3) 3832.6(2)4 42.054 2.14420.33 20.080.713/0.905 0.727/0.85660 606544 (0.0420) 11 112(0.0587)5349 9542318 5590.0291 0.03180.0672 0.05671.021 1.003

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luminescence spectra observed were corrected for the nonlinearresponse of the instrument using predetermined factors. Thecrystals for these measurements were packed in quartz capil-laries. Phosphorescence lifetimes (s) were averaged for at leastthree independent measurements, monitoring the decay at themaxima of the emission spectra. The single decays wereanalyzed with Origin 7.0 soware.

Fig. 2 IR spectra in the n(CO) range of FcC(O)CH3 (0.003 M, 230 K,solid line) and in the presence of (CuL)3 (0.003M) in hexane at differenttemperatures: 290 K (dotted line), 260 K (dash-dotted line), 240 K(dash line), d¼ 0.12 cm.

Fig. 3 IR spectra FcC(O)CH2Ph in different solvents: hexane (solid line)THF (dash-dotted line), CH2Cl2 (dash line), CH3CN (dotted line), atroom temperature.

Results and discussion(a) Complex formation in solution

Complexation of FcC(O)CH3 with (ML)3. Acetylferrocene hasthe band of the n(CO) stretching vibration at 1685 cm�1 insolution (hexane), the intensity of this band decreases in thepresence of (ML)3 while the new low frequency n(CO) bandsappear at 1624 cm�1 (M ¼ Cu) and 1616 cm�1 (M ¼ Ag) (Fig. 1and 2). By the analogy with the spectra of complexes of organicketones with (ML)3 (ref. 7) these new bands are assigned ton(CO)bond vibrations of bonded CO group in the complexes with(ML)3.

The intensity of n(CO)init bands decreases and the intensityof n(CO)bond bands increases with the macrocycle concentration(Fig. 1) similarly to that observed for organic ketones uponcomplexation with these macrocycles.7 The redistribution ofn(CO)init–n(CO)bond intensities is observed with the temperaturechange (see for example, Fig. 2). It is caused by the shi of thecomplex formation equilibrium to the right upon cooling.Moreover, these changes are reversible.

Variable temperature 1H and 13C NMR spectra of FcC(O)CH3–(AgL)3 mixture in CD2Cl2 conrm formation of thecomplex with the CO group as the site of coordination. 13C NMRresonance of the carbon atom in CO group (d 201.41 ppm)undergoes the low eld shi (Dd ¼ 0.91 ppm) upon addition ofthe equimolar amount of macrocycle at room temperature, thevalue of the shi (Dd) increases upon cooling to 1.63 ppm at213 K. The larger shis at low temperatures are due to theincrease of the formation constants relative to those at 297 K.The 13C signals of other carbon atoms are less sensitive

Fig. 1 IR spectra in the n(CO) range of FcC(O)CH3 (0.003 M, solid line)and in the presence of (AgL)3: 0.0015 M (dotted line), 0.003 M (dash-dotted line), 0.006 M (dash line). Hexane, T ¼ 290 K, d ¼ 0.12 cm.

8352 | RSC Adv., 2014, 4, 8350–8359

(Dd # 0.45 ppm) even at low temperatures. The 1H resonancesof all the protons of 1 undergo small high-eld shi (Dd #

0.12 ppm) in the presence of (AgL)3 at 213 K. At room temper-ature no changes in the 1H NMR spectra were observed.

Conformations of FcC(O)CH2Ph in solution. Despite(phenylacetyl)ferrocene is known since 1960's it turned out thatbeing rather peculiar in solution its IR spectra were described inthe solid state only.11–13 The two n(CO) bands are found in IRspectra of FcC(O)CH2Ph in solution in contrast to the singleband in the KBr pellets. Their positions depend on the solvent(hexane, CH2Cl2, THF, CH3CN) shiing to the lower frequenciesin more polar and coordinating one. At that the relative inten-sity of the higher frequency band increases and two bandsbroaden and overlap on going from hexane to THF and evenmore in CH3CN and CH2Cl2 (Fig. 3).

The relative intensities of the n(CO) bands depend on thetemperature: the lower frequency band becomes more intenseupon cooling. These features appear to be similar to those of the

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Scheme 1 Hindered rotation around the C(O)–CH2X bond in 2.

Fig. 5 IR spectra in the n(CO) range of FcC(O)CH2Ph (0.004 M, solidline) and in the presence of (CuL)3: 0.002 M (dash line), 0.004 M (dash-dotted line), 0.008 M (dotted line) in hexane, T ¼ 290 K, d ¼ 0.22 cm.

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substituted acetophenones: Ph–C(O)–CH2–X (X ¼ Ph, Hal andCN), evidencing coexistence of the cis- and gauche-conforma-tions in solution due to the hindered rotation around the C(O)–CH2X bond (Scheme 1).14

The authors14 have attributed the high frequency band to thecis-conformer, conrming assignment of Bellamy et al. (made atthe examples of a-halogenated cyclohexanones15) where the cis-form was considered as thermodynamically more stable. So, thecharacter of conformational equilibrium is the same inphenylacetophenone14 and (phenylacetyl)ferrocene.

The dynamic behavior of the 1H and 13C NMR resonances ofthe interacting groups of 2 (in CD2Cl2) also conrms the ideaabout hindered rotation. Thus, the doublet of the phenylo-protons in 1H NMR shis from 7.30 ppm to 7.23 ppm uponcooling. In contrast the resonances of p-, m-protons and of CH2

group exhibit the negligible shi (Fig. 4). The 13C NMR signal ofCO group of 2 depends slightly on temperature being201.80 ppm at 290 K and 201.92 ppm at 200 K (Dd ¼ 0.12 ppm)whereas the corresponding acetylferrocene signal is substan-tially more sensitive to cooling (Dd ¼ 1.51 ppm). The competi-tion between the effects of hindered rotation inducingsignicant up-eld shi and of temperature change leading to

Fig. 4 1H NMR spectra of FcC(O)CH2Ph at different temperatures inCD2Cl2 (Ph and CH2 signals).

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down-eld shi could explain abnormally small temperaturedependence of the 13C(O) resonance of 2.

Signicant up-eld shi upon the temperature change from290 to 200 K is observed for the 13C NMR resonance of CH2

group carbon and C-1 atom of the phenyl ring (from 47.10 to46.15 ppm, Dd ¼ 0.95 ppm; and from 136.02 to 134.95 ppm, Dd¼ 1.07 ppm, respectively). Smaller but again up-eld shis ofthe other Ph ring carbon atoms resonances were observed (Dd¼0.65–0.46 ppm). We believe all these changes evidence hinderedrotation around CH2–Ph bond slowed at the NMR time scale bythe temperature decrease.

Complexation of FcC(O)CH2Ph with (ML)3. An addition ofthe macrocycles to the solution of 2 in hexane leads to thedecrease of the two initial n(CO) bands (1688, 1674 cm�1) andappearance of new low frequency bands – 1614 cm�1 and1618 cm�1 belonging to the stretching vibration of CO groupcoordinated to macrocycle in complexes {[(CuL)3]$[2]} and{[(AgL)3]$[2]}, respectively (Fig. 5). Increase of the macrocycleconcentration leads to further intensity growth of these newbands. Since the molar absorption of n(CO) bands is an order ofmagnitude lower for 2 relative to 1, we were forced to use muchhigher ketone and consequently the macrocycle concentrationsto achieve reasonable IR absorption intensities. Under theseconditions the n(CN) stretching vibrations of the pyrazolateligand become observable in the spectra at 1642 cm�1

(for (CuL)3) and 1632 cm�1 (for (AgL)3).Low temperature 13C NMR spectra in CD2Cl2 support the

formation of complex: the signal of CO group (d ¼ 201.91 ppmat 213 K) shis signicantly to low eld upon addition of theequimolar amount of (AgL)3 (Dd ¼ 1.98 ppm), while other 13Csignals exhibit the small high-eld shis (Dd# 0.4 ppm). Underthese conditions the 1H spectra reveal very small low-eld shis(Dd # 0.1 ppm).

Thus, all the IR and NMR data conrm interaction betweenCO group of (phenylacetyl)ferrocene 2 and the macrocycle as inthe case of acetylferrocene 1.

Thermodynamics of complexes formation. Composition ofthe complexes of 1 and 2 with bothmacrocycles was determined

RSC Adv., 2014, 4, 8350–8359 | 8353

Fig. 6 The Job's plot: dependence of the n(CO)bond band intensity of{[(AgL)3]$[1]} (1624 cm�1) on the composition of the isomolar solutionof 1 and (AgL)3, hexane.

Fig. 8 UV-vis spectra of FcC(O)CH3 (c ¼ 0.0045 M, 290 K, solid line)and in the presence of (AgL)3 (0.0045 M) in hexane at differenttemperatures: 290 K (dotted line), 250 K (dash-dotted line) and 230 K(dash line), d ¼ 0.22 cm.

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by the isomolar series method using the n(CO)bond bandchanges (Job's method). It was established that only complexes1 : 1, i.e. one molecule of the ketone per one molecule of (ML)3,are formed at molar ratios from 7 : 1 to 1 : 7 for all four ketone–macrocycle combinations (see for example, Fig. 6).

The complex formation constants at different temperatureswere determined from the n(CO)free bands intensity changes;the enthalpy and entropy values of the complexes {[(ML)3]$[1]}in hexane were calculated by the Van't Hoff method.

Very poor solubility of 2 in hexane at low temperatures andsmall intensity n(CO)free of (phenylacetyl)ferrocene comparing tothe acetylferrocene prevented the use of the IR spectra for thedeterminationof the thermodynamicparameters for {[(ML)3]$[2]}complexes formation. So, we used UV-vis spectroscopy,that allowed to measure the spectra at smaller concentrations(c0 ¼ 0.002 M) without precipitation at low temperatures(<270 K).

UV-vis spectra of (phenylacetyl)ferrocene in hexanefeature two bands: at 450 nm (3 ¼ 305 l mol�1 cm�1) and at

Fig. 7 UV-vis spectra of FcC(O)CH2Ph (0.002 M, 290 K, solid line) andin the presence of (AgL)3 (0.002 M) in hexane at different tempera-tures: 290 K (dotted line), 250 K (dash-dotted line) and 230 K (dashline), d ¼ 0.4 cm.

8354 | RSC Adv., 2014, 4, 8350–8359

322 nm (3 ¼ 1020 l (mol�1 cm�1)). The broad band withmaximum at 450 nm is assigned to bathochromically shied (by9 nm) transition of the ferrocene which intensity is increased(cf. 3ferrocene ¼ 87 l (mol�1 cm�1)) due to the mixing of chargetransfer and the ligand eld transition as in acylferrocenes.16–18

The band at 322 nm belongs to MLCT transition with a chargetransfer from Cp to CO-substituent which stabilizes the result-ing exited states.16 The inection at 384 nm caused by conju-gation between the orbitals of the cyclopentadienyl ring and theadjacent carbonyl.17 The UV bands of acetylferrocene havethe same structure (447 nm; 3¼ 302 l (mol�1 cm�1) and 319 nm;3 ¼ 1144 l (mol�1 cm�1)).

Addition of the macrocycle (AgL)3 to the solution of 2 inhexane induces the noticeable bathochromic shi and theintensity increase of the initial ferrocenyl ketone bands. Thebands intensities grow further upon cooling (Fig. 7). The similarspectral changes are observed for 1 in the presence of (AgL)3(Fig. 8). The band maximum of the ferrocene transition in thecomplex was chosen as the analytical point for determination ofthe formation constants (463 nm for {[(AgL)3]$[1]} and 465 nm

Fig. 9 Van't-Hoffplots (dependenceR ln K/1000on1/T) for {[(AgL)3]$[1]}from IR (solid) and from UV-vis (dotted) experiments in hexane.

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Table 2 Constants (at selected temperatures) and thermodynamic characteristics of complexes formation

Kform (290 K),l/mol � 10�3

Kform (270 K),l/mol � 10�3

Kform (250 K),l/mol � 10�3

�DH�,kcal mol�1

�DS�,cal (mol�1 K�1)

{[(CuL)3]$[1]} 0.2 0.6 1.5 7.8 � 0.3 16 � 2{[(AgL)3]$[1]} 1.1 4.2 21.4 10.9 � 0.3 24 � 3{[(AgL)3]$[2]} 0.7 1.3 5.4 7.3 � 0.1 12.5 � 0.5

Fig. 10 Molecular structures of bipyramidal complexes {[([3,5-(CF3)2Pz]Cu)3]$2[1]} (top) and {[([3,5-(CF3)2Pz]Ag)3]$2[1]} (bottom). Thehydrogen atoms are omitted for clarity; thermal ellipsoids are drawn atthe 30% probability level.

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for {[(AgL)3]$[2]}). Unfortunately, the shied band of{[(AgL)3]$[R2CO]} complex is overlapping with the initial band offerrocenyl ketone 1 or 2 (Fig. 7) and this necessitated the eval-uation of the need to take into account an impact of the non-bonded ferrocenyl ketone absorbance in the intensity of theband of the complex. To solve this problem we studied theUV-vis spectra of 1 complexation with (AgL)3, for which thethermodynamic data were determined by IR.

Employment of formation constants of {[(AgL)3]$[1]} derivedfrom IR measurements at 290 K allowed us to calculate theequilibrium concentrations for both forms of the ketone(bonded and non-bonded) and the extinction coefficients fortheir UV-vis bands (see ESI† for procedure details). This way theformation constants at different temperatures were determinedtaking into account the impact of the non-bonded ketoneabsorption and using the maximum of the band as the analyt-ical point. The comparison of the linear dependences of ln Kform

on 1/T derived from the UV-vis and IR data (Fig. 9) shows thatthe Van't Hoff plots have close slopes. Consequently thedifference in thermodynamic characteristics of {[(AgL)3]$[1]}formation is very small (DH� ¼ �10.4 � 0.4 kcal mol�1 and DS�

¼ �22 � 3 e.u. from UV-vis data and DH� ¼ �10.9 � 0.3 kcalmol�1 and DS� ¼ �24 � 3 e.u. determined by IR), being in thelimits of the experimental error.

Thus we calculated the thermodynamic parameters of{[(AgL)3]$[2]} using this approach: Kform (290 K) was determinedfrom the IR spectra and those at lower temperatures – fromUV-vis spectra.

All determined thermodynamic parameters of complexes aregathered in Table 2.

Formation constants of complexes with acetylferrocene are1.5–4 times higher than those of (phenylacetyl)ferrocene, thisdifference is larger at low temperatures which leads to therelatively large entropy effect in the case of [(ML)3]$[1]complexes. The complex of 2 with (AgL)3 is signicantly weaker(has smaller DH�) in comparison with {[(AgL)3]$[1]} that is inline with the electron withdrawing effect of CH2Ph group incomparison with the CH3 group.

Formation constants of copper complexes are an order ofmagnitude lower than those of silver complexes for 1 at alltemperatures as well as room temperature constants for 2 (Kform

(290 K) ¼ 0.1 � 103 l mol�1 for {[(CuL)3]$[2]} and 0.7 � 103

l mol�1 for {[(AgL)3]$[2]}). Thus, complexes with Ag-macrocyclesare signicantly more stable than those with (CuL)3. This trendis qualitatively the same as for the complexes with organicketones7 but opposite to the complexes of these macrocycleswith p-electron ligands.6

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(b) Complexes in the solid state

X-ray study of [FcC(O)CH3]/[(ML)3] complexes. The crystalsof 1 with (CuL)3 and (AgL)3 were precipitated from equimolarsolutions of the reactants in CH2Cl2–hexane mixture. The singlecrystal X-ray analysis revealed that both complexes have similarcomposition 2 : 1, that is twomolecules of 1 per onemolecule ofmacrocycle differing from that in solution (1 : 1) and featurebipyramidal structure. Notable the 2 : 1 complexes are obtainedfrom solutions of both 1 : 1 and 2 : 1 molar ratio of the

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Table 3 Selected interatomic distances (A) and bond angles (deg.) forthe complexes of 1 with (CuL)3 and (AgL)3 in the crystals

{[([3,5-(CF3)2Pz]Cu)3]$2[1]}

Cu(1)–O(1) 2.643(3) Cu(1)–O(2) 2.599(3)Cu(2)–O(1) 2.567(3) Cu(2)–O(2) 2.665(3)Cu(3)–O(1) 2.587(3) Cu(3)–O(2) 2.624(3)Cu(1)–N(1) 1.885(4) O(1)–C(17) 1.238(5)Cu(1)–N(6) 1.891(3) C(16)–C(17) 1.499(6)Cu(2)–N(2) 1.883(3) C(17)–C(18) 1.456(6)Cu(2)–N(3) 1.879(3) O(2)–C(29) 1.241(5)Cu(3)–N(4) 1.891(3) C(28)–C(29) 1.488(6)Cu(3)–N(5) 1.880(3) C(29)–C(30) 1.457(7)N(1)–Cu(1)–N(6) 176.8(2) C(18)–C(17)–C(16) 118.2(4)N(3)–Cu(2)–N(2) 177.5(2) O(2)–C(29)–C(30) 120.9(4)N(5)–Cu(3)–N(4) 176.8(2) O(2)–C(29)–C(28) 120.8(5)O(1)–C(17)–C(18) 121.0(4) C(30)–C(29)–C(28) 118.3(4)O(1)–C(17)–C(16) 120.7(4)

{[([3,5-(CF3)2Pz]Ag)3]$2[1]}a

Ag(1)–O(1) 2.615(2) Ag(2)–O(1) 2.675(2)Ag(1A)–O(1) 2.763(2)Ag(1)–N(1) 2.136(2) O(1)–C(17) 1.233(3)Ag(1)–N(3) 2.147(2) C(16)–C(17) 1.500(3)Ag(2)–N(2) 2.115(2) C(17)–C(18) 1.461(3)N(1)–Ag(1)–N(3) 174.25(7) O(1)–C(17)–C(18) 120.6(2)N(2)–Ag(2)–N(2A) 179.07(11) O(1)–C(17)–C(16) 120.6(2)

C(18)–C(17)–C(16) 118.8(2)

a The atoms labeled with A were generated with symmetrytransformation of �x + 1, y, �z + 1.5.

Fig. 11 Fragments of polymer chains in the crystals of {[([3,5-(CF3)2Pz]Cu)3]$2[1]} (left) and {[([3,5-(CF3)2Pz]Ag)3]$2[1]} (right). The H and Fatoms are omitted for clarity.

Fig. 12 Molecular structure of complex {[([3,5-(CF3)2Pz]Ag)3]$[2]} inthe crystal. The hydrogen atoms are omitted for clarity; thermalellipsoids are drawn at the 30% probability level.

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reactants. The structure is characterized by triple coordinationof oxygen atom to each metal atom of the macrocycle (Fig. 10).No observable contacts between Fc-fragments and the macro-cyclic molecule were found in the complexes. All signicantinteratomic distances are presented in Table 3.

There is an appreciable difference in the structure of the Cuand Ag containing complexes in spite their general similarity.The two crystallographically independent molecules of ace-tylferrocene in the complex {[(CuL)3]$2[1]} are disposedsymmetrically relative to the macrocycle plane and are relatedby the pseudocenter of symmetry. The macrocycle has near toplanar structure (maximum deviation from the median planeequals to 0.08 A for the N(5) atom). All six independentdistances Cu/O are in the narrow range 2.567(3)–2.665(3) A(mean value 2.61 A), that is less than the formal sum of the vander Waals radii for Cu/O (2.92 A).19 These distances areappreciably shorter than those observed previously in thecrystal of the complex of (CuL)3 with benzophenone (Ph2CO).7

The latter is composed of two molecules of (CuL)3 per onemolecule of ketone. Its wedge-shaped sandwich structure isformed by coordination of the oxygen atom of the CO group toonly one copper atom in both macrocycles [Cu/O 2.879(4) A].The lengths of the Cu/O contacts in the complex {[(CuL)3]$2[1]} correspond to the weak coordination found between the twocoordinated copper(I) atoms and oxygen containing anions(perchlorate, sulfate, nitrate, triate and others �2.50 to2.75 A).20–23

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The complex {[(AgL)3]$2[1]} occupies a special position in thecrystal on the twofold axis passing through the Ag(2) andthe middle point of N(3)–N(3A) bond, see Fig. 10. Despite thepresence of a crystallographic symmetry this complex has lesssymmetric structure than it's “copper” analogue. The macro-cycle is bent (maximal deviation from the medium plane is0.24 A for the N(3) atom). The lengths of Ag/O interactions(2.615(2)–2.763(2) A, mean value 2.68 A) are, just as expected,larger than those in the copper analogue, but signicantlyshorter than the sum of the van der Waals radii for Ag/O(3.42 A).19 Note that such multicenter coordination was

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Fig. 13 Fragment of infinite chain in the crystal of {[([3,5-(CF3)2Pz]Ag)3]$[2]}. The H and F atoms are omitted for clarity.

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observed for the complex {[(AgL)3]$[Ph2CO]}, however the Ag/Odistances were longer (2.768(3)–2.952(4) A).7

Besides the mentioned difference in molecular structure theassociation of complexes {[(CuL)3]$2[1]} and {[(AgL)3]$2[1]} incrystals is also signicantly different. It is possible to identify acommon motif of their crystal structures corresponding to 1Dpolymeric stack in which the complexes are integrated bystacking interactions between the acetylferrocene molecules(Fig. 11). However in the case of “copper” complex the stackinginteraction is implemented through the ten carbon atoms of thetwo substituted Cp rings of the crystallographically indepen-dent FcC(O)CH3 molecules of the neighboring complexes(the distances C/C0.5�x, 0.5+y, z ¼ 3.388(6)–3.602(6) A, thedistance between the planes of the adjacent Cp rings is 3.45 A,the distance between their centroids is 3.47 A, the dihedralangle is 0.0�). In “silver” complex the stacking interaction isimplemented through the carbon atom of the acetyl group andthe substituted Cp fragment of the adjacent molecule of 1(the distance C(17)/C(22)1�x, �y, 1�z is 3.241(3) A, the distancebetween the planes of the adjacent Cp rings is 3.05 A, thedistance between their centroids �4.75 A, the dihedral angle isequal to 0.0�). In both cases the pairs of approaching each otheracetylferrocene molecules are sandwiched between the twomacrocyclic molecules, which planes are parallel to each otherin the crystal of the “silver” complex and inclined with dihedralangle of 41.4� in the crystal of the “copper” complex.

Complex of [FcC(O)CH2Ph] with [(AgL)3]. Complex of [FcC(O)CH2Ph] with [(AgL)3] has the 1 : 1 composition in the solid stateand the pyramidal structure (Fig. 12), as in the case of thecomplex of (AgL)3 with Ph2CO.7 The complex is formed bycooperative interaction of oxygen atom with three metal atomsof the macrocycle. All Ag/O distances (2.676(2)–2.908(2) A)(Table 4) are appreciably shorter than the formal sum of the vander Walls radii. These values are close to those obtained for thepyramidal 1 : 1 complex with Ph2CO, but longer than the Ag/Odistances in the bipyramidal complex with acetylferrocene. Asin the case of complex {[(AgL)3]$2[1]} the macrocycle is notice-ably bent in {[(AgL)3]$[2]} (maximal deviation from theplane passing through silver and nitrogen atoms is 0.27 A forthe N(5) atom).

Table 4 Selected interatomic distances (A) and bond angles (deg.) forthe complex of 2 with (AgL)3 in the crystal

Ag(1)–O(1) 2.803(2) C(29)–Ag(3A)a 3.367(4)Ag(2)–O(1) 2.908(2) C(31)–Ag(2A)a 3.417(4)Ag(3)–O(1) 2.676(2) C(32)–Ag(2A)a 3.056(4)

C(33)–Ag(2A)a 3.187(4)Ag(1)–N(1) 2.091(3) Ag(1)–N(6) 2.087(3)Ag(2)–N(2) 2.133(3) O(1)–C(26) 1.227(4)Ag(2)–N(3) 2.129(3) C(23)–C(26) 1.452(5)Ag(3)–N(4) 2.111(3) C(26)–C(27) 1.521(5)Ag(3)–N(5) 2.117(3)N(6)–Ag(1)–N(1) 174.4(1) O(1)–C(26)–C(23) 122.7(3)N(3)–Ag(2)–N(2) 169.8(1) O(1)–C(26)–C(27) 121.1(3)N(4)–Ag(3)–N(5) 175.9(1) C(23)–C(26)–C(27) 116.2(3)

a The atoms labeled with A were generated with symmetrytransformation of �0.5 + x, 1.5 � y, z.

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The presence of the additional coordination site in (phe-nylacetyl)ferrocene (the phenyl substituent) in comparison toacetylferrocene leads to a signicant difference in the crystalstructure of their complexes. The innite stacks of the 1 : 1composition are formed by {[(AgL)3]$[2]} via alternating themacrocycle and (phenylacetyl)ferrocene molecules (Fig. 13).Each (phenylacetyl)ferrocene molecule is bonded with the twoneighboring macrocycles in the stack by different ways: inaddition to the multicentered coordination of the oxygen atomof CO-group to three Ag atoms of one macrocycle there is theAg/p interaction of the phenyl group with the second macro-cycle (Ag/C distances are 3.056(4)–3.417(4) A; the phenyl planeis parallel to the plane of this macrocycle with the anglebetween them 1.7�). Cp ligands do not participate in the inter-molecular interactions with macrocycles. The planes of twomacrocycles form the angle 23.0�.

Note, the ferrocenyl fragments do not participate in inter-molecular interactions with macrocycles in all three structureswith 1 and 2. In addition, no metallophilic interactions areobserved which are typical for the crystal structures of themacrocycles containing d10 metals and observed in all struc-tures of the complexes of (CuL)3 and (AgL)3 with Ph2CO.7

In the case of {[(AgL)3]$[2]} complex it is difficult todiscriminate which of the two types of interactions between 2and (AgL)3 (cooperative interaction of the carbonyl groupoxygen atom with Ag atoms or Ag/p interaction with phenylsubstituent) should be considered as the key interaction(stronger and structure forming). On the one hand, the Ag/Odistances are signicantly shorter than Ag/C(Ph) contacts andthe spectral data pointed to involvement of the carbonyl groupin the interaction in solution. On the other hand, maximaldistortion of the linear coordination of the metal atoms isobserved for Ag(2) atom (N(3)–Ag(2)–N(2) angle is 169.8(1)�)whose participation in the interaction with p-system of the Phsubstituent is dominant.

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Table 5 Photoluminescence characteristics of the initial macrocycle (CuL)3 and complexes of (CuL)3 with 1 and 2

lem (Dla), nm t, msec

(CuL)3 {[(CuL)3]$[2]} {[(CuL)3]$[1]} (CuL)3 {[(CuL)3]$[2]} {[(CuL)3]$[1]}

298 K 648 654 (+6) 660 (+12) 49.0 47.7 � 0.5 58 � 1.577 K 668 671 (+3) 673 (+5) 64.4 65.2 � 0.8 77.2 � 1.7

a (Dl ¼ lcomp � l(CuL)3).

Fig. 14 Photoluminescence spectra (solid line) of crystals of (CuL)3 aswell as complexes with acetylferrocene (dotted) and with (phenyl-acetyl)ferrocene (dash-dotted) at 298 K (left) and 77 K (right). lexc was290 nm.

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Luminescence properties. The luminescence properties ofthe macrocycles (ML)3 (M ¼ Ag, Cu) bonded with acetylferro-cene and (phenylacetyl)ferrocene were studied in the solid state.The bright red luminescence of (CuL)3 complexes with ferro-cene derivatives was observed at room and liquid nitrogentemperatures while no luminescence was found for thecomplexes {[(AgL)3]$[1]} and {[(AgL)3]$[2]}. Free (AgL)3 macro-cycle exhibits the blue emission withmaximum at 465 nm at lowtemperature only (77 K) in agreement with the literature data.1

The obtained photophysical data for the initial macrocycle(CuL)3 and complexes {[(CuL)3]$[1]} and {[(CuL)3]$[2]} areprovided in Table 5 and photoluminescence spectra are pre-sented in Fig. 14. Notice, that lemmax positions and the life time (s)values obtained for (CuL)3 are in line with the literature data.1

The complexation of (CuL)3 with 1 and 2 leads to rather smallbathochromic lemmax shis (3–12 cm�1) and slight increase of thes values. The determined lifetime values are in the range of 45–77 msec that corresponds to the phosphorescence. Thermo-chromism is evident from the observed lifetime increase uponcooling (Table 5). All characteristics increase in the samesequence as the strength of the complexes: {[(CuL)3]$[2]} <{[(CuL)3]$[1]}.

Thus, the luminescent properties are strongly dependent onthe metal, being quenched in the case of complexes of 1 and 2with Ag containing macrocycle, and appearing as bright redphosphorescence with Cu analogue. This fact calls for thefuture study with DFT calculations support and a larger series ofcomplexes.

Conclusions

The results of the (AgL)3 and (CuL)3 complexation with carbonylsubstituted ferrocenes and comparison with the previously

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obtained data on the complexes of these macrocycles withorganic ketones allow to draw the rst conclusions about thegeneral features of the structure, the sites of coordination andthe strength of the complexes. The oxygen atom of the CO groupis the site of the ketone coordination in all these compoundsboth in solution and in the solid state. This is the rst casewhen the functional group competes successfully with p-systemof organic and organometallic compounds. The 1 : 1 composi-tion was established for all complexes in solution. The strength(formation constants and enthalpies) of the complexesdecreases in the sequence: FcC(O)CH3 > FcC(O)CH2Ph >MeC(O)Et$ Ph2CO. The silver complexes are stronger Lewis acids thanthe copper ones in the interaction with the same base. Impor-tantly, the luminescent properties of ([3,5-(CF3)2Pz]M)3 (M¼ Ag,Cu) bonded with acetylylferrocene and (phenylacetyl)ferroceneare strongly dependent on the metal and show the bright redphosphorescence in the case of Cu.

The composition and the structure vary in the solid state,however the main feature of ketone-macrocycle complexes – COgroup as a primary coordination site – is preserved. In all casesthe interactions with the p-density of the ferrocene Cp rings areabsent. The structural diversity of the complexes is based on themacrocycles aptitude to coordinate the external guest moleculesat both sides of the macrocycle. Obviously when the guestmolecule does not possess several coordination sites (e.g. (COT)Fe(CO)3,6 FcC(O)CH3), the saturation of (ML)3 sites is achievedin 1 : 2 complexes (two guest molecules per one (ML)3), whileformally 1 : 1 complexes turned to have the composition 2 : 2and are packed as dimers due to argentophilic interactions (e.g.[(AgL)3]$[Ph2CO]).7 When the guest molecule provides thepossibility to coordinate two macrocycles yielding innitestacks of 1 : 1 composition as in the case of complexes with 2,ferrocene6 or mesitylene.4

Acknowledgements

Authors thank Dr L. Puntus and Prof. N. Belkova for helpfuldiscussions. This work was supported by the Russian Founda-tion for Basic Research (projects 12-03-00872 and 13-03-01176),the Division of Chemistry and Material Sciences of RAS.

Notes and references

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