Synthesis and spectroscopic studies of new hydridoruthenium complexes: catalytic reactions of [RuHCl(bpzm)(cod)] (bpzm = bis(pyrazol-1-yl)methane, cod = cycloocta-1,5-diene)

Abstract

The reaction of [RuHCl(bpzm)(cod)] ( 1) (bpzm = bis(pyrazol-1-yl)methane, cod = cycloocta-1,5-diene) with one equivalent of AgCF 3SO 3 afforded the triflate-containing [RuH(CF 3SO 3)(bpzm)(cod)] ( 2). The reaction of 2 with PMe 2Ph allowed the synthesis of trans-[RuH(PMe 2Ph)(bpzm)(cod)]CF 3SO 3 (bd3a), which isomerizes easily to cis-[RuH(PMe 2Ph)(bpzm)(cod)]CF 3SO 3 ( 3b), while a similar reaction of 1, in the presence of AgCF 3SO 3, gave a series of phosphine-containing complexes such as [RuH(CF 3SO 3)(cod)(PMe 2Ph) 2] ( 4), the products of this process greatly depending on the reaction conditions. The complex trans-[RuH{P(OMe) 3}(bpzm)(cod)]CF 3SOP 3 ( 5a), which also readily isomerizes to cis[RuH{P(OMe) 3}(bpzm)(cod)]CF 3SO 3 ( 5b), was isolated from the reactions of 2 with P(OMe) 3, or alternatively from the reaction of 1 with P(OMe) 3 and AgCF 3SO 3. Finally, the reaction of 2 or 1 (in the presence of AgCF 3SO 3) with N-donors pyridine, 4-methylpyridine (4-picoline) or 3,5-dimethylpyridine (3,5-lutidine) yielded a mixture of products which we believe to contain both cis- and trans-[RuHL(bpzm)(cod)]CF 3SO 3 (L = pyridine, 4-picoline, or 3–5-lutidine). Spectroscopic data are provided for these compounds. Complex 1 catalyzes both the hydrogenation of the unsaturated substrates cyclohexene, cyclohexanone, acetone and propanal, with turn-over rates of up to 1506 h −1 for cyclohexanone in the presence of NaOH at 130°C, and the efficient transfer hydrogenation of cyclohexanone by propan-2-ol in the presence of NaOH at 80°C, with a turn-over rate of 880 h −1.