Abstract
A likely pathway of decomposition of halosilanes in the upper atmosphere is 1,2-HX elimination, leading to a species following the form SiX2CY2(X and/or Y=F and/or Cl). While some of these molecules are predicted to be planar using ab initio and DFT methods, geometry optimizations of several of these species leads to a non-classical trans-bent structure confirmed by using multiple levels of theory. In order to probe the nature of bonding in these trans-bent geometries, Quantum Theory of Atoms in Molecules (QTAIM) was employed using electron densities generated at the same level of theory as optimization. The Laplacian of the electron density shows critical points indicative of regions of high electron localization-bonding electron domains and non-bonding electron domains. The presence of two unusual critical points above and below the near plane of the molecule, along with the longer than expected C-Si bond strongly suggest a single bond with singlet-biradical character of the two electrons not used in bonding. Compounds with a planar geometry lack these two unusual critical points and have a shorter C-Si bond length. This proposed singlet-biradical species is a new theory to explain trans-bending within molecules.
How to Cite
Williams, C., (2013) “QTAIM Studies of the C-Si Bonding in Geometrically Non-Classical Chlorofluorosilenes”, Capstone, The UNC Asheville Journal of Undergraduate Scholarship 26(2).
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