THEORETICAL-STUDY OF THE ACTIVATION OF THE O-H BOND IN WATER BY 2ND-ROW TRANSITION-METAL ATOMS

The reaction between the entire sequence of second-row transition-metal atoms and water has been studied using methods including electron correlation of all valence electrons. Three regions of the potential surface were investigated, the molecular complexes, the O-H insertion products and the transition states for the oxidative addition reaction. The results are compared to previous studies on the C-H insertion reaction in methane and the N-H insertion reaction in ammonia. The molecular complexes are found to be weaker bound than the corresponding ammonia adducts. The insertion products are stronger bound for the atoms to the left and slightly weaker bound for the atoms to the very right than the products of the ammonia reaction. The barrier heights are in all cases lower for the ammonia reaction. The presence of two lone pairs in water which are bound more tightly than the single lone pair in ammonia is of key importance to explain these trends.