Molecular orbital studies of titanium nitride chemical vapor deposition: gas phase beta-elimination

Chemical vapor deposition (CVD) of titanium nitride can be carried out usin g Ti(NR2)(4) and NH3 (R = Me or Et). Imido compounds are thought to be key intermediates in this process. Formation of Ti(NR2)(2)=NH from TI(NR2)(4) c an proceed by ligand exchange with NH3 followed by elimination of NHR2. Whe n R = Et there is an alternate beta -elimination pathway that also leads to imido formation. At the B3LYP16-311G(d) level of theory, this pathway has a barrier of 51.1 kcal/mol and the reaction is endothermic by 68.0 kcal/mol . By comparison, ligand exchange has a barrier of 35.5 kcal/mol, suggesting that beta -elimination does not contribute significantly to Ti(NR2)(2)=NH formation. (C) 2001 Published by Elsevier Science B.V.