Sigma-hole bonding (B�A-R) is commonly described as a non-covalent interaction between a negative site (B; example a lone pair of electrons or anion) and a positive region on the surface of a group IV-VII atom (A) in a molecule (A-R; R is an electron-withdrawing atom or group) [1]. Recently, greater emphasis has been placed on sigma-hole interactions involving group IV elements (C, Si, Ge) acting as the electron acceptors. This increased interest may be largely due to the biological and chemical significance of carbon-based molecules in particular, as well as the potential applications of sigma-hole bonding in these molecules [2-4]. For a given B and A, good correlations between the interaction energy, (?E), of neutral B�A-R complexes and the maximum positive surface potential on A along the extension of the R-A bond, Vs,max (R-A), have been documented in the literature [5].In the present work, a study of model anionic sigma-hole complexes X�CH3Y (X = F-, Cl-, Br-, Y = Br, Cl, F) is reported at the MP2/6-311++G(d,p) level. For a fixed anion X, the strength of X�C-Y interactions correlates well with the C-Y dipole polarizabilities in the CH3Y monomers and inversely related to Vs,max (R-A). This trend also holds for X�Si/GeH3Y complexes. These species were also optimized using different computational methods (SCF, MP2, M062X, QCISD) and it was found that the M062X functional was the least accurate procedure for modelling these interactions compared with the QCISD results as a benchmark. The NBO and QTAIM analyses for these complexes showed that the geometrical and frequency changes can be adequately explained based on the redistribution of the CH3Y electron density upon complex formation.References P. Politzer, K. E. Riley, F. A. Bulat and J. S. Murray, Comp. Theor. Chem. 2012  , 998, 2-8; and references cited therein.A. Bauz�, T. J. Mooibroek and A. Frontera, Angew. Chem. Int. Ed. 2013  , 52, 12317�12321.D. Mani and E. Arunan, Phys. Chem. Chem. Phys. 2013  , 15, 14133�14512.S.J. Grabowski, Phys. Chem. Chem. Phys. 2014  , 16, 1824-1834.A. Bundhun, P. Ramasami, J. S. Murray and P. Politzer, J. Mol. Model 2013  , 19, 2739-2746.

Trends In model anionic sigma-hole bonded complexes: X�AH3Y (X = F-, Cl-, Br-; A = C, Si, Ge; Y = F, Cl, Br)

248th National Meeting (2014)

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