Synthesis and characterization oftrans-dihalogeno(isonitrosoketonato) (isonitrosoketone)osmium(III)

Summary Reaction of OsX₆]^2– (X = Cl or Br) with HK HK = PhC(=O)C(=NOH)R; R=H, Me or Ph] yielded osmium(III) complexes of the type OsX₂(K)(HK)]. The OsX₂ group wastrans and the hydrogen-bonded (K)(HK) moiety behaved as a planar tetradentate N₂O₂ chelator. The complexes were one-electron paramagnets and exhibited characteristic osmium(III) e.p.r. spectra. Several spin-allowed and spin-forbidden charge-transfer transitions were observed in the 200–1300 nm region.