Electrophilic behaviour of co-ordinated nitrogen mono-oxide: preparation and reactions of halogenonitrosylbis[o-phenylenebis(dimethylarsine)]osmium complexes
Abstract
The complexes trans-[Os(pdma)2X(NO)]X2·H2O [X = Cl, Br, or I; pdma =o-phenylenebis(dimethylarsine)] were prepared from [OsX5(NO)]2– and pdma. They react reversibly with [OH]– to give [Os(pdma)2X(NO2)]. The complex [Os(pdma)2Cl(NO)]Cl2·H2O and hydrazine hydrate give [Os(pdma)2Cl(N3)], which reacts with O2 to give [Os(pdma)2Cl(NO2)] and with HCl to give trans-[Os(pdma)2Cl(N2)]Cl. Treatment of a mixture of [Os(pdma)2Cl(N3)] and [Os(pdma)2Cl(NO2)] with HCl gives trans-[Os(pdma)2Cl(N2)]Cl and cis-[Os(pdma)2Cl(NO)]Cl2. The complex cis-[Os(pdma)2Cl(NO)]Cl2 and [OH]– gives trans-[Os(pdma)2(NO)(OH)]Cl2. Treatment of trans-[Os(pdma)2Cl(NO)]Cl2·H2O with phenylhydrazine gives trans-[Os(pdma)2Cl(N2)]Cl and [Os(pdma)2Cl(ONNNHPh)]. The latter complex undergoes free-radical reactions with O2 in various solvents to give [Os(pdma)2Cl(N2)]Cl, [Os(pdma)2Cl(NO2)], or [Os(pdma)2Cl(NO)]Cl2·H2O, or mixtures of these, depending on the conditions. The complex [Os(pdma)2Cl(NO)]Cl2·H2O and hydroxylamine gave trans-[Os(pdma)2(NO)(OH)]Cl2 together with other unidentified products. The physical and chemical properties of all the complexes are reported.