Preparation and crystal structure of trichloro(thionitrosyl)bis(triphenylphosphine)osmium, [Os(NS)Cl3(PPh3)2]

The compound (NSCl)3 reacts with [MCl2(PPh3)3](M = Os or Ru) in tetrahydrofuran to give the thionitrosyl complexes [M(NS)Cl3(PPh3)2][M = Os (1) or Ru (2)]. Nitrosyl chloride or bromide converts (1) to the corresponding nitrosyl complex. Crystals of (1) are monoclinic, space group I2/a, with a= 1 615.9(6), b= 943.7(5), c= 2 250.6(10) pm, β= 103.02(3)°, and Z= 4. The structure was refined to R= 0.042 for 2 076 diffractometer data. The osmium is octahedrally co-ordinated with the phosphines cis to the NS group; a crystallographic two-fold axis along the Cl–Os–N–S bonds imposes linearity at nitrogen, with Os–N 177.9(9), N–S 150.3(10), Os–P 245.9(2), Os–Cl(cis) 238.7(3), and Os–Cl(trans) 239.9(3) pm. Complex (2) is apparently isostructural, with a= 1 613.5(15), b= 941.8(4), c= 2 249.3(15) pm, and β= 102.94(3)°.