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)

Article abstract of DOI:10.1016/0022-328X(95)05836-E

The reaction of [RuHCl(bpzm)(cod)] (1) (bpzm = bis(pyrazol-1-yl)methane, cod = cycloocta-1,5-diene) with one equivalent of AgCF₃SO₃ afforded the triflate-containing [RuH(CF₃SO₃)(bpzm)(cod)] (2). The reaction of 2 with PMe₂Ph allowed the synthesis of trans-[RuH(PMe₂Ph)(bpzm)(cod)]CF₃SO₃ (3a), which isomerizes easily to cis-[RuH(PMe₂Ph)(bpzm)cod)]CF₃SO₃ (3b), while a similar reaction of 1, in the presence of AgCF₃SO₃, gave a series of phosphine-containing complexes such as [RuH(CF₃SO₃)(cod)(PMe₂Ph)₂] (4), the products of this process greatly depending on the reaction conditions. The complex trans-[RuH{P(OMe)₃}(bpzm)(cod)]CF₃SO₃ (5a), which also readily isomerizes to cis-[RuH{P(OMe)₃}(bpzm)(cod)]CF₃SO₃ (5b), was isolated from the reaction of 2 with P(OMe)₃, or alternatively from the reaction of 1 with P(OMe)₃ and AgCF₃SO₃. Finally, the reaction of 2 or 1 (in the presence of AgCF₃SO₃) 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)]CF₃SO₃ (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.