Preparation and properties of nitrosyl complexes of ruthenium(0)

Abstract

The complex [RuCl(CO)(NO)(PPh₃)₂] has been obtained by interaction of the hydride, [Ru(H)Cl(CO)(PPh₃)₃] with N-nitroso-N-methyltoluene-p-sulphonamide. The choride ligand is easily displaced to afford a series [RuX(CO)(NO)(PPh₃)₂](X = OH, Br, I, N₃, NCO, NCS, or HCO(₂). In contrast to this lability of the anionic ligand, the neutral carbonyl group is not displaced by an excess of triphenylphosphine and the phosphine ligands are inert towards exchange. l.r. spectra (4000–200 cm.^–1) of the new compounds are reported. The values of ν(NO) show a marked ligand (X) dependence ranging from 1642 (X = 1) to 1555 cm.^–1(X = OH). The compounds are monomeric in solution and in the solid state the iodide has trigonal bipyramidal geometry with a linear nitrosyl group and axial phosphines. The geometry of other members of the series is not certain and the hydroxide, judging by its low nitrosyl stretching frequenct, may have a bent nistroyl group. The zerovalent compounds are oxidised by halogens, Y₂, with loss of carbon monoxide, to the divalent nitrosyl compounds [RuXY₂(NO)(PPh₃)₂]. Similar oxidative additions occur with CCl₄, CHCl₃, and HgCl₂the last reaction being accompanied by elimination of mercury. Methyl iodide does not add but in an unusual reaction converts to [RuCl(CO)(NO)(PPh)₃)₂] to [Rul(CO)-(NO)(PPh₃)₂]. [RuCl₃(NO)(PPh₂CH₃)₂] has been prepared by ligand exchange and shown to have trans phosphine groups by n.m.r. spectroscopy; all the compounds [RuXY₂(NO)(PPh₃)₂] are believed to have the same phosphine arrangement.