Stepwise conversion of [Os(CF3CO2)2(CO)4] into [Os(pyS)2(CO)2]: X-ray crystal structures of the complexes [Os(pyS)2(CO)x] where x= 2 or 3 and pyS is the pyridine-2-thionato ligand
Abstract
The tetracarbonyl osmium(II) complex [Os(CF3CO2)2(CO)4] or its decarbonylated derivative [Os(CF3-CO2)2(CO)3] reacts with pyridine-2-thione (pySH) in refluxing chloroform by substitution and addition respectively to give the compound fac-[Os(CF3CO2)2(pySH)(CO)3] containing monodentate trifluoroacetate ligands and S-bonded pySH. This complex spontaneously eliminates trifluoroacetic acid in the same refluxing solvent to give fac-[Os(CF3CO2)(pyS)(CO)3] which has bidentate pyS and monodentate trifluoroacetate. The same reagents in refluxing toluene give [Os(pyS)2(CO)3] but no further decarbonylation occurs unless this tricarbonyl complex is treated with Me3NO at room temperature and then [Os(pyS)2(CO)2] is formed. The single-crystal X-ray structures of the complexes [Os(pyS)2(CO)3] and [Os(pyS)2(CO)2] have been determined; the former contains non-interconverting monodentate and bidentate pyS but both ligands are chelating in the latter. Four intermediates in the overall conversion of [Os(CF3CO2)2(CO)4] into [Os(pyS)2(CO)2] are identified. This complex may also be synthesised by the direct reaction of pyridine-2-thione with [Os3(CO)12].
Please wait while we load your content...
