Formation of hexaosmium raft clusters from [Os₆(CO)₁₆(MeCN)₂]: Synthesis, structural characterisation and reactivities of [Os₆(CO)₁₆(μ₃-η²-C₅H₄NS)₂] and [Os₆(CO)₁₇(μ-H)(μ₄-η²-C₅H₄NS)]

Reaction of [Os₆(CO)₁₆(MeCN)₂] with 1 equivalent of 2-Aldrithol in CH₂Cl₂ under ambient conditions afforded two new raft clusters [Os₆(CO)16(µ₃-η²-C₅H₄NS)₂] 1 and [Os₆(CO)₁₇(µ-H)(µ4-η²-C₅H₄NS)] 2 in moderate and fair yields, respectively. Cyclic voltammograms of compound 1 exhibited two metal-based, one-electron reduction couples at E1/2 = –0.36 and –0.20 V together with an irreversible ligand-based anodic wave at ca. Epa = +0.31 V vs. Ag–AgNO₃. Protonation of 1 with CF₃CO₂H produced an unstable species [Os₆(CO)₁₆(µ₃-η²-C₅H₅NSH)(µ₃-η²-C₅H₅NS)][CO₂CF₃] 3, which upon standing in CH2Cl2 quickly decomposed. All compounds have been fully characterised by spectroscopic methods, while the molecular structures of 1 and 2 were established by crystallographic techniques. Both 1 and 2 contain ‘ladder’-type and edge-fused raft cluster cores, with the sulfur atom in 2 being drawn intimately into the cluster envelope. These clusters serve as good models for substrates adsorbed onto metal surfaces.