Microwave Spectra and Structure of CF3I···PH3 by chirped-pulse spectroscopyin context of the CF3I···B and ClI···B series

Susanna L. Stephens, Nick R. Walker, Antony C. Legon

69th International Symposium on Molecular Spectroscopy, Champaign-Urbana, Illinois20th June 2014

“A halogen bond R-X Y-Z occurs when there is evidence of a net attractive interaction between an electrophilic region on a halogen atom X belonging to a molecule or a molecular fragment R-X (where R can be another atom, including X, or a group of

atoms) and a nucleophilic region of a molecule, or molecular fragment, Y-Z.”

Gautam R. Desiraju, P. Shing Ho, Lars Kloo, Anthony C. Legon, Roberto Marquardt, Pierangelo Metrangolo, Peter A. Politzer, Giuseppe Resnati, and Kari Rissanen. Denition of the halogen bond, IUPAC Provisional Recommendation. http://www.halogenbonding.eu/

The more of the following features of halogen bonding below that are satisfied the more reliable an identification of a halogen bond:1) The length of the bond X Y will tend to be less than the sum of their Van de Waal radii of the atoms, X and Y.2) The angle R-X Y will tend to be linear as the halogen will align with the lone-pair or π-systemof the halogen acceptor. This angle may be perturbed slightly by other bonding effects elsewhere in the molecular system.3) The covalent bond R-X will tend to increase upon bond to the halogen acceptor.4) The strength of the halogen bonding will decrease when the electronegativity of X increases and the ability of R to withdraw electrons decreases.5) Although the relative dependence of different bonding forces varies, the two primary bonding mechanisms are dispersion and electrostatic effects (which includes polarisation).6) Electron density topology analysis tends to show a bond path X and Y and a bond critical point between X and Y.7) Vibrational modes corresponding with the bond X Y are present upon bonding and vibrational modes in the Raman and IR regions of R-X and Y-Z are suitably shifted.8) A characteristic shift to the blue is usually observed in the UV-visible spectrum of the halogen bond donor when the X Y bond is formed.9) Typically the formation of the X Y bond will also change the characteristic nuclear magnetic resonance signals of R-X and Y-Z.10) The halogen X may be involved in multiple halogen bonds.11) The halogen bond may be included in reaction mechanisms including halogen transfer reactions.

Halogen Bonding in the Gas-phase: A Comparison of the Iodine Bond in B···ICl and B···ICF3 for simple Lewis Bases B

J Grant Hill, Anthony C Legon, David P Tew and Nicholas R Walker, Topics in Current Chemistry: Halogen Bonding: Impact on Materials Chemistry and Life Sciences

C∞V

C∞V

C2V

C3V

Cs at equilibrium

C2V in zero point state

Cs in equilibrium and zero point state

C3V

C3V

CSHighest symmetry

C3V

CSHighest symmetry

CSHighest symmetry

CSHighest symmetry

C3VHighest symmetry

C3VHighest symmetry

C2V

Newcastle CPFTMW Spectrometer

S. L. Stephens, N. R. Walker, J. Mol. Spectr., 263, 27 (2010) 0.00 6.25 12.50Frequency /MHz

~400 000 averages 1 % CF3I, 1 % PH3 balance 6 bar Ar

Frequency /MHzFrequency /MHz

Frequency /MHz

107AgI109AgI

Frequency /MHz

Frequency /MHz

C3v Symmetric top ? Internal rotation?

CF3I···NH3 & CF3I···N(CH3) 3 Susanna L. Stephens, Nicholas R. Walker and Anthony C. Legon, Phys. Chem. Chem. Phys., 13, 20736 (2011)CHnYnX··NH3 G. Valerio, G. Raos, S. V. Meille, P. Metrangolo and G. Resnati, J. Phys. Chem. A, 104, 1617 (2000) CH3I···NH3 G. T. Fraser, F. J. Lovas, R. D. Suenram, D. D. Nelson, Jr. and W. Klemperer, J. Chem. Phys., 84, 5983 (1986)

22JKm

2JM

2JΚ0R )1())1()((H JJDJJKmDmDKDB J

The Hamiltonian

garm.c.

Geometric model

Frequency /MHz

Frequency /MHz

Assigned spectra of 12CF3I PH∙∙∙ 3

84Kr 57.0 %86Kr 17.3 %82Kr 11.6 %83Kr 11.5 %

12CF3I PH∙∙∙ 3 Spectral constants

A-state E-stateB0 /MHz 544.232815(97) (544.232815)DJ /Hz 125.21(28) 125.25(24)

DJK /kHz 1.9502(62) 1.9841(61)DJm /kHz - 44.57(18)ηJ /kHz - 16.416(16)

χaa (I) /MHz -2167.77(11) -2167.853(88)N 236 395

σr.m.s. /kHz 10.4 11.4

garm.c.

12CF3I84Kr k = 2.798(2) N m-1

12CF3ICOk = 3.950(2) N m-1

12CF3IPH3 k = 6.27(2) N m-1

µ𝑆𝑢𝑏𝑢𝑛𝑖𝑡𝑠=𝑚𝐶𝐹3 𝐼𝑚𝐵/ (𝑚𝐶𝐹 3𝐼+𝑚𝐵 )𝐼𝑏𝑏≅ µ𝑠𝑢𝑏𝑢𝑛𝑖𝑡𝑠 𝑟𝑚 . 𝑐 .

2 +𝐼𝑏𝑏B

2(1+cos2𝛼 )+ 𝐼𝑐𝑐

B

2(sin 2𝛼 )+ 𝐼𝑏𝑏

C F 3 I

2(1+cos2𝛾 )+ 𝐼 𝑐𝑐

CF 3 I

2(sin2𝛾 )

Model of subunit oscillation

𝛾𝑎𝑣𝑔=cos−1( 2 𝜒 𝑎𝑎

3 𝜒0+ 13 )

½

D. J. Millen. Can. J. Chem., 63, 1477 (1985)

CF3I···CO and CF3I···Kr J. Chem. Phys., 135, 224309 (2011)CF3I···C2H4 J. Mol. Spec., 280, 47 (2012)CF3I···NH3 and CF3I···N(CH3)3 PCCP, 13, 20736 (2011)CF3I···H2O and CF3I···H2S PCCP, 13, 21093 (2011)

α /° (B)

γ /° (CF3I)

CF3Irm.c. /Å

Kr - 5.0(5) 4.7201

OC 10(3) 4.0(5) 4.9644(12)

NH3 20.3(12) 4.12(37) 3.997(1)

N(CH3)3 16.2(20) (4.12) 4.080(2)

H2O 34.4(20) (<5.0) -

H2S 93.7(2) (<5.0) -

PH3 (20) (5) -

N2 - - -

C2H4 - - -

C2H2 - - -

Determined geometries

α /° (B)

γ /° (CF3I)

CF3Irm.c. /Å

CF3Ir(Z···I)/Å

ClIr(Z···I)/Å

Δr /Å

Kr - 5.0(5) 4.7201 3.8299(7) - -

OC 10(3) 4.0(5) 4.9644(12) 3.4281(12) 3.011(1) 0.417(2)

NH3 20.3(12) 4.12(37) 3.997(1) 3.039(1) 2.711(2) 0.327(3)

N(CH3)3 16.2(20) (4.12) 4.080(2) 2.781(2) - -

H2O 34.4(20) (<5.0) - 3.0517(18) 2.828(1) 0.225(3)

H2S 93.7(2) (<5.0) - 3.5589(2) 3.154(3) 0.405(4)

PH3 (20) (5) - 3.571(3) 2.963(1) 0.608(4)

N2 - - - 3.438(1) 3.180(2) 0.258(3)

C2H4 - - - 3.424(2) 3.032(2) 0.402(4)

C2H2 - - - 2.442(2) 3.115(2) 0.327(4)

Intermolecular stretching force constants and disassociation energies

kσ /(N m-1) De /(kJ Mol-1)

B···ICF3 B···ICl B···ICF3 B···ICl

N2 2.94(2) 5.35(2) 4.3 7.2

OC 3.950(2) 7.96 6.3 13.0

HCN ··· 14.5(1) 14.0 23.9

C2H4 4.95(1) 14.0(1) 10.4 21.9

C2H2 4.96(7) 12.1(1) 9.4 17.6

H2O 8.8(1) 15.9(2) 15.0 24.9

H2S 6.7(1) 16.55(5) 10.8 23.2

PH3 6.27(2) 20.7(1) 10.7 29.7

NH3 11.6(2) 30.4(3) 22.7 47.2

D. J. Millen. Can. J. Chem., 63, 1477 (1985)De calculated by CCSD(T)(F12*)/cc-pVDZ-F12 level of theory where basis set superposition is accounted for by counterpoise correction

kσ (B···I)

/(N m-1)

Halogen Bonding in the Gas-phase: A Comparison of the Iodine Bond in B···ICl and B···ICF3 for simple Lewis Bases B

J Grant Hill, Anthony C Legon, David P Tew and Nicholas R Walker, Topics in Current Chemistry: Halogen Bonding: Impact on Materials Chemistry and Life Sciences

Electric charge redistribution

Halogen Bonding in the Gas-phase: A Comparison of the Iodine Bond in B···ICl and B···ICF3 for simple Lewis Bases B

J Grant Hill, Anthony C Legon, David P Tew and Nicholas R Walker, Topics in Current Chemistry: Halogen Bonding: Impact on Materials Chemistry and Life Sciences

Acknowledgements

University of NewcastleNick WalkerDaniel ZaleskiDavid HirdDror Bittner

University of BristolTony C. LegonDavid TewColin M. Western

Halogen Bonding in the Gas-phase: A Comparison of the Iodine Bond in B···ICl and B···ICF3 for simple Lewis Bases B

J Grant Hill, Anthony C Legon, David P Tew and Nicholas R WalkerTopics in Current Chemistry: Halogen Bonding: Impact on Materials Chemistry and Life Sciences