Reactions of CS2 with metal cluster carbonyls of the iron triad: reaction of [Os6(CO)18] and X-ray crystal structure of [Os4(CO)12(CS)S

Abstract

The reaction of [Os6(CO)18] with excess CS2 in heptane at 165 °C under CO pressure gives the known compounds [Os3(CO)8(CS)S2](1) and [Os3(CO)9S2](2), and also [Os4(CO)12(CS)S](3). A single crystal X-ray diffraction study shows that in (3) the four Os atoms adopt a ‘butterfly’ configuration, but with an Os ⋯ Os separation of 3.598(2)A across the ‘backbone’, which is non-bonding. Three of the Os atoms are capped by a µ3-S ligand, while a CS ligand, which acts as a four-electron donor, lies on the other side of the metal framework. The carbon atom of this ligand is co-ordinated to all four metal atoms but the sulphur atom is only co-ordinated to one. The molecule (3) crystallises in space group P with a = 14.834(6), b= l0.048(5), c= 7.682(5)A, α= 108.84(3), β= 92.99(3), γ= 95.64(3)° and Z= 2. The structure was solved by a combination of direct methods and Fourier difference techniques, and refined by blocked-cascade least squares to R= 0.058 for 3 249 observed diffractometer data.