Insertion of carbon monoxide into the scandium-hydrogen bond of scandium dichloride hydride

Abstract

Correlated ab initio theoretical calculations at the valence double-zeta plus polarization level are used to study the insertion of carbon monoxide into a scandium-hydrogen sigma bond. The authors find a Lewis acid-Lewis base interaction between scandium and the carbon monoxide of 16.4 kcal/mol. The reaction occurs with a relatively small activation energy (..delta..E/sup double dagger/ = 23.7 kcal/mol. with respect to the Lewis acid-base complex) leading to an eta/sup 2/-formyl complex. The reaction is moderately exothermic (..delta..E = -6.1 kcal/mol with respect to the Lewis acid-base complex). The explanation for the small barrier is precisely the same as for previously studied metallo 2 + 2 reactions. The effect of polarization functions and electron correlation on the position of the transition state and exothermicity of the reaction were also studied.