Formation of hexaosmium raft clusters from [OS_6(CO)_(16)(MeCN)_2]: synthesis, structural characterisation and reactivities of [Os_6(CO)_(16~-) (#mu#_3-#eta#~2-C_5H_4NS)_2] and [OS_6(CO)_(17)(#mu#-H)(#mu#_4-#eta#~2-C_5H_4NS)]

摘要

Reaction of [Os_6(CO)_(16)(MeCN)_2]with 1 equivalent of 2-Aldrithol in CH_2Cl_2 under ambient conditions afforded two new raft clusters [Os_6(CO)_(16)(#mu#_3-#eta#~2-C_5H_4NS)_2] 1 and [Os_6(CO)_(17)(#mu#_4-#eta#~2-C_5H_4NS)] 2 in moderate and fair yields, respectively. Cyclic voltammograms of compound 1 exhibited two metal-based, one-electron reduction couples at E_(1/2) = -0.36 and -0.20 V together with an irreversible ligand-based anodic wave at can. E_(pa) = +0.31 V vs. Ag-AgNO_3. Protonation of 1 with CF_3CO_2H produced an unstable species [Os_6(CO)_(16)(#mu#_3-#eta#~2-C_5H_5NSH)(#mu#-3-#eta#~2-C_5H_5NS)][CO_2CF_3] 3, which upon standing in CH_2Cl_2 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.