ChemInform Abstract: Complexes of the Platinum Metals. Part 37. Benzotriazole and 5,6-Dimethylbenzotriazole Derivatives. X-Ray Crystal Structure of Carbonylhydrido(hydrogenbis(benzotriazolato))bis(triphenylphosphine)osmium(II)

The ruthenium and osmium complexes [MH(Cl)(CO)(PPh3)3](M = Ru or Os) each react with benzotriazole (Hbta) in cold benzene to form a pair of geometrical isomers [MH(Cl)(Hbta)(CO)(PPh3)2](H trans to Hbta or Cl). The dihydrides [MH2(CO)(PPh3)3] react with excess of benzotriazole in boiling benzene (M = Ru) or toluene (M = Os) to afford products of the form [MH(bta ⋯ H–bta)(CO)(PPh3)2] containing a hydrogen-bonded benzotriazole–benzotriazolate pair co-ordinated as an NN′ chelate ligand. Similar chelate ligands are found in the products trans-[M(bta ⋯ H–bta)2(Hbta)(PPh3)] obtained from [RuH2(PPh3)4] and Hbta in boiling benzene, or from [MCl2(PPh3)3], Hbta, and triethylamine in boiling benzene (M = Ru) or toluene (M = Os). Isomeric forms of the complexes trans-[M(bta ⋯ H–bta)2(Hbta)(PPh3)] are thought to involve N2- or N3-co-ordinated Hbta ligands. Treatment of [IrCl(CO)(PPh3)2] with Hbta leads to reversible formation of the oxidative-addition product [IrH(Cl)(bta)(CO)(PPh3)2] in solution. The same reagents in the presence of NEt3 afford the known complex [Ir(bta)(CO)(PPh3)2]. Benzotriazole also reacts with mer-[IrH3(PPh3)3] to form [IrH2(bta ⋯ H–bta)(PPh3)2] and with [Pt(PPh3)4] to generate [Pt(bta)2(PPh3)2]. The nature of the hydrogen-bonded composite (bta ⋯ H–bta) ligand has been confirmed by an X-ray diffraction study on the osmium complex [OsH(bta ⋯ H–bta)(CO)(PPh3)2]. The crystals are triclinic, space group P, with a= 10.059(4), b= 11.876(1), c= 20.629(3)A, α= 74.57(1), β= 83.08(2), γ= 65.96(2)°, and Z= 2. A parallel series of complexes have been obtained using 5,6-dimethylbenzotriazole.