Reactions of unsaturated quinoline triosmium clusters [Os3(CO)9(μ3-η2-C9H5(4-R)N)(μ-H)] (R = Me or H) with tetramethylthiourea:: X-ray structures of [Os3(CO)8(μ-η2-C9H5(4-Me)N) (η2-SC(NMe2NCH2Me)(μ-H)2] and [Os3(CO)9 (μ-η2-C9H6N)(η1-SC(NMe2)2)(μ-H)]

Treatment of the electronically unsaturated 4-methylquinoline triosmium cluster [Os-3(CO)(9)(mu 3-eta(2) -C9H5(4-Me)N)(mu-H)] (1) with tetramethylthiourea in refluxing cyclohexane at 81 degrees C gave [Os-3(CO)(8) (mu-eta(2)-C9H5(4-Me)N) (eta(2)-SC(NMe2NCH2-Me)(mu-H)(2)] (2) and [Os-3(CO)(9)(mu-eta(2)-C9H5(4-Me)N)(eta(1)-SC(NMe2)(2))(mu-H)] (3). In contrast, a similar reaction of the corresponding quinoline compound [Os-3(CO)(9)- (mu(3)-eta(2)-C9H6N)(mu-H)] (4) with tetramethylthiourea afforded [Os-3(CO)(9)( (mu-eta(2)-C9H6N)(eta(1)-SC(NMe2)(2))(mu-H)] (5) as the only product. Compound 2 contains a cyclometallated tetramethylthiourea ligand which is chelating at the rear osmium atom and a quinolyl ligand coordinated to the Os-3 triangle via the nitrogen]one pair and the C(8) atom of the carbocyclic ring. In 3 and 5, the tetramethylthiourea ligand is coordinated at an equatorial site of the osmium atom, which is also bound to the carbon atom of the quinoylyl ligand. Compounds 3 and 5 react with PPh3 at room temperature to give the previously reported phosphine substituted products [Os-3(CO)(9)(mu-eta(2)-C9H5(4-Me)N)(PPh3)(mu-H)] (6) and [Os-3(CO9(mu-eta(2)-C9H6N)(PPh3)(mu-H)] (7) by the displacement of the tetramethylthiourea ligand.