Structure of Chloronitrosyl(η2-sulfur dioxide)bis(triphenylphosphine)ruthenium-Dichloromethane, RuCl(NO)(η2-SO2)(P(C6H5)3)2.CH2Cl2

Chloronitrosyl(η2-sulfur dioxide)bis(triphenylphosphine)ruthenium, RuCl(NO)(η2-SO2)(PPh3)2, on the basis of an X-ray structure determination of its CH2Cl2 solvate, is shown to possess η2 coordination of the SO2 group to the Ru atom. About the Ru atom are trans axial PPh3 groups and a basal plane consisting of the Cl ligand, the NO ligand (with Ru-N-O linear), and the S,O bonded SO2 group. As opposed to the η2 coordination of CO2 and CS2 to transition metals, wherein the metal-ligand systems are planar, atom 0(2), which is not bonded to the Ru atom, is 1.24 A out of the plane of atoms Ru, S, and 0(1). Through the use of S18O2 it was established that a weak band at 895 cm-1 in the spectrum of the compound containing S16O2 arises from the presence of SO2. The geometrical features of the present structure are compared with those in Rh(NO)(η2-SO2)(PPh3)2, the only other example where η2 coordination of SO2 has been established. The compound RuCl(NO)(SO2)(PPh3)2-CH2Cl2 crystallizes in space group Ci1-P1 of the triclinic system with two formula units in a cell of dimensions a=13.629 (2) Å, b=15.255 (3) Å, c=10.106 (2) Å, α=92.70 (1)°, β=104.41 (2)°, γ=65.48 (1)°, V= 1848 Å3, Pcalcd=1-498 g/cm3, and pobsd=1.51 (1) g/cm3. The structure has been refined to a conventional R index on Fo of 0.063 on the basis of 182 variables and 5379 observations.