Trans/cis isomerization of [RuCl2(diphosphine)(diamine)] complexes: synthesis, X-ray structure and catalytic activity in hydrogenation.

The diamine (N-N) co-ligand 2,2-dimethyl-1,3-propanediamine and 2,3-diaminophathalene react individually with [RuCl(2)(dppb)(2)(μ-dppb)] to afford complexes with kinetically stable trans-[Cl(2)Ru(dppb)(N-N)] as the favoured isomer. The thermodynamically stable cis-[Cl(2)Ru(dppb)(N-N)] isomer of complex 1 was formed from the trans-1 isomer. The trans to cis isomerization reaction was conducted in CHCl(3) at RT and monitored by (31)P{(1)H} NMR. The structures of the desired complexes were characterized via elemental analyses, IR and, UV-visible spectroscopy, FAB-MS and NMR. The structure of the cis-1 isomer was determined by single crystal X-ray measurements. Both the trans-1 and cis-1 isomers were shown to have a significant catalytic role in selective hydrogenation reactions under mild conditions using cinnamic aldehyde as typical model reaction.