SYNTHESIS AND REDUCTIVE S-O CLEAVAGE OF SULFUR OXIDE CLUSTERS - [PPN][HFE3(CO)9SO2] AND [PPN]2[FE3(CO)9SO]

The cluster [PPN][HFe3(CO)9SO2] (II) was synthesized by reaction of [P PN][HFe3(CO)11] (I) with SO2 and was characterized by infrared spectro scopy, H-1 and C-13 NMR spectroscopy, X-ray crystallography, and cycli c voltammetry. The SO2 ligand binds in an unusual mu3-eta2 configurati on and acts as a four-electron donor. The hydride ligand in II was det ected by NMR spectroscopy, and a site for its location is evident in t he structure. Acetylation of II followed by reduction with NaPh2CO yie lds the known sulfido cluster [Fe3(CO)9S]2- (III). Reduction of [PPN]- [HFe3(CO)9SO2] without prior acetylation leads to formation of [PPN]2[ Fe3(CO)9SO] (IX). This cluster was characterized by infrared spectrosc opy, NMR spectroscopy, and X-ray crystallography. [PPN]2[Fe3(CO)9SO] c ontains an SO ligand bonded symmetrically to all three iron atoms. Cry stallographic data for II: space group I2/a, a = 36.565(9)angstrom, b = 13.756(2) angstrom, c = 17.648(4) angstrom, beta = 90.87(2)degrees, V= 8876(6) angstrom3. Crystallographic data for IX: space group Cc, a = 29.333(5) angstrom, b = 14.481(4) angstrom, c = 25.048(4) angstrom, beta = 134.44(1)degrees.