Bonding analysis of telluroketones H2A=Te (A = C, Si, Ge)

Quantum chemical calculations using density functional theory BP86/def2-TZVPP and ab initio methods at CCSD(T)/def2-TZVPP have been carried for the telluroketones H(2)A=Te (A = C, Si, Ge). DFT calculations have also been carried out for the ketones H2C=E (E = O, S, Se, Te) and for the complexes NHC ->[H(2)A=Te]-> B(C6F5)(3). The nature of the bonding has been investigated with charge-and energy decomposition analyses. The calculated bond dissociation energies for the double bonds of the H2C=E and H(2)A=Te molecules show the expected trends O > S > Se > Te for atom E and C > Si > Ge for atom A. Complexation of the telluroketones in NHC ->[H(2)A=Te]-> B(C6F5)(3) leads to longer and weaker A-Te bonds which exhibit the surprising trend for the bond dissociation energy Si>Ge>C. The contribution of the p bonding in H(2)A=Te increases for the heavier atoms with the sequence C < Si < Ge.