Synthesis, Structure, and Reactivity of an Osmacyclopentene Complex

Treatment of OsCl2(PPh3)2(CHC­(PPh3)­CH­(OH)-η2-CCH) (1) with PPh3 and Bu4NCl in CH2Cl2 under air gave paramagnetic osmacyclopentene [OsCl2(PPh3)2(CHC­(PPh3)­CH­(OH)­C­(CH­(PPh3)))]Cl (5). Heating the suspension of 5 in CH2Cl2 under a nitrogen atmosphere led to the formation of η2-allene-coordinated osmacycle OsCl2(PPh3)­(CHC­(PPh3)­CHCCH­(P­(C6H4)­Ph2)) (6) and chloro-osmabenzene OsCl2(PPh3)2­(CHC­(PPh3)­CHCClCH) (7) via disproportionation reaction. Oxidative transformation of 5 under an oxygen atmosphere yielded osmafuran [OsCl­(PPh3)2­(CHC­(PPh3)­CHO)­(CC­(PPh3))]Cl (10). In addtion, complexes 6, 7, and 10 can also undergo ligand substitution reactions with NaSCN to afford more stable analogues.