Synthesis and characterization of trans-dihalogeno(isonitrosoketonato) (isonitrosoketone)osmium(III).

Reaction of [OsX] (X = Cl or Br) with HK [HK = PhC(=O)C(=NOH)R; R=H, Me or Ph] yielded osmium(III) complexes of the type [OsX(K)(HK)]. The OsX group was trans and the hydrogen-bonded (K)(HK) moiety behaved as a planar tetradentate NO 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. [ABSTRACT FROM AUTHOR]