Mechanismus der Wasserstoffübertragung bei der homogenen katalytischen Hydrierung von Malein- und Fumarsäuredimethylester mit IrCl(CO)(PΦ3)2 / Mechanism of Hydrogen Transfer in Homogeneous Catalytic Hydrogenation of Maleic- and Fumaric-Dimethyl Ester with IrCl(CO)(PΦ3)2

Abstract

Hydrogen transfer from the hydrogenated catalyst IrH2 to an unsaturated compound S is a two step mechanism. In the π-complex IrH2...S the first hydrogen atom is transferred by formation of σ-complex IrH(SH). This reaction is reversible. The transfer of the second hydrogen is not reversible. Distribution of deuterium in the products and isomerisation give evidence of rotation of substrate in the π-complex and of rotation of group-CHDR in the σ-complex. Results of hydrogenation with tritium confirm the proposed mechanism.