Synthesis of triosmium alkylidyne clusters incorporating pendant pyridyl ligands. Crystal structures of [Os3(μ-H)2(CO)9{μ3-C(4,4′-bipy)}] · H2O and [Os3(μ-H2(CO)9{μ3-C(2,4′-bipy)}] (4,4′-bipy = 4,4′-bipyridine; 2,4′-bipy = 2,4′-bipyridine)

Reaction of [Os3(μ-H)3(CO)9(μ3-CCl)] with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in the presence of an excess of 4,4′-bipyridine (4,4′-bipy) or 2,4′-bipyridine (2,4′-bipy) yields [Os3(μ-H)2(CO)9{μ3-C(4,4′-bipy)}] (1) and [Os3(μ-H)2(CO)9{μ3-C(2,4′-bipy)}] (2), respectively, in good yields. Both complexes, which contain externally directed pendant pyridyl groups capable of ligation to other metal centres, have been fully characterised by spectroscopic and X-ray diffraction methods. Chemical reactivities of 1 with H+, AuPPh3+and [Os3(μ-H)3(CO)9(μ3-CCl)] are also described.