Journal of the American Chemical Society, Vol.118, No.40, 9772-9777, 1996
Theoretical-Studies on the Decomposition Mechanism of Tetraalkyl Titanium Complexes
Unimolecular and bimolecular methane eliminations of TiMe(4) have been studied using nb initio molecular orbital theory. Geometry optimizations were performed with the 3-21G and HW3 (equivalent to the 6-31G*) basis sets. The energies were further evaluated with the MP2/HW3 calculations. We predict a high activation energy for unimolecular methane elimination but a low activation energy for bimolecular methane elimination. For Ti(CH2-CMe(3))4, neopentane elimination through alpha- and gamma-hydrogen abstractions has been studied with the 3-21G basis set. We predict an intrinsic preference for alpha-hydrogen abstraction over gamma-hydrogen abstraction. This preference is enhanced by the bulkiness of the alkyl ligands.
Keywords:CHEMICAL-VAPOR-DEPOSITION;METAL ALKYLIDENE COMPLEXES;OLEFIN METATHESIS;ALKYLCHROMIUM PRECURSORS;ORGANOMETALLIC COMPOUNDS;CARBENE COMPLEXES;CHROMIUM CARBIDE;HIGH-VALENT;TRANSITION;FILMS