TRANSITION-METAL HYDRIDE COMPLEXES AS LEWIS-BASES - PREPARATION AND CRYSTAL-STRUCTURE OF (RR,SS)-([(ETA-5-C5H5)RU(PPH3)(CNTBU)]2(MU-H))PF6.CH2CL2

Alkylation of [(eta-5-C5H5)Ru(PPh3)(CN(t)Bu)H] (1) with Ph3CPF6, Et3OBF4, or Me3OBF4 leads to formation of the dimeric salts {[(eta-5-C5H5)Ru(PPh3)(CN(t)Bu)]2(mu-H)}PF6 (2) and {[(eta-5-C5H5)Ru(PPh3)(CN(t)Bu)]2(mu-H)}BF4 (3), respectively, with low diastereoselectivity. Hydrogenation of the molecular hydrogen complex [(eta-5-C5H5)Ru(PPh3)(CN(t)Bu)(eta-2-H2)]PF6 (4) leads to the formation of 2 with high diastereoselectivity (SS,RR : RS,SR = 97 : 3). The reaction of the carbonyl hydride [(eta-5-C5H5)Ru(PPh3)(CO)H] (5) with Ph3CPF6 leads to a diastereomeric mixture of the cations {[(eta-5-C5H5)Ru(PPh3)(CO)]2(mu-H)}PF6 (6). The major diastereomer of 2 has been characterised by a single crystal X-ray structural determination.