Ethylene addition to Ru(=CH2)(=O)3 - A theoretical study

Quantum chemical calculations using density functional theory (B3LYP) were carried out to elucidate the reaction pathways for ethylene addition to the ruthenium compound RuO3CH2. These investigations show that the parent compound is relatively unstable and its rearrangement gives access to very diverse isomers and addition products with comparable relative energies and reaction barriers. The results are compared to our previous study on the analogous osmium system OsO3CH2 and we show that reactivity of both compounds towards ethylene is quite similar. In both cases, the [3 + 2](C,O) cycloaddition pathway is preferred kinetically and thermodynamically. The exothermicity (-68.8 kcal/mol) of this reaction is higher for the ruthenium system than for the osmium homologue. While this pathway is unrivaled for the osmium system, the [3 + 2](O,O) cycloaddition pathway is able to compete kinetically for the ruthenium system. (C) 2008 Elsevier B.V. All rights reserved.