The syntheses, structures and stereodynamics of transition metal complexes of 1,1′-bis(methylthio)ruthenocene. Crystal structure of 1,1′-bis(methylthio)ruthenocene tetracarbonyltungsten

Abstract

The complexes cis-[M(CO) 4(LL)], fac-[ReX(CO) 3(LL)] and fac-[PtXMe 3(LL)], (M = Cr, Mo, W; LL = [(C 5H 4SCH 3) 2Ru]; X = Cl, Br, I) have been synthesised. A 1H NMR study of their solution properties has shown that pyramidal inversion of the coordinated sulphur atoms is rapid on the NMR timescale at ambient temperature. At low temperatures (ca. −90° C) the motion is arrested and the tungsten complex exists as a mixture of meso and dl species in approximately equal proportions, whereas the rhenium complexes are predominantly (> 94%) in the meso form. Insolubility precluded low-temperature studies on the platinum complexes. Variable temperature bandshape analyses of the tungsten complex yielded a sulphur inversion ( meso → dl) value of Δ G ≠ (298 K) 32.0 ± 1.0 kJ mol −1. The massive predominance of one invertomer in the case of the rhenium complexes prevented a study of the sulphur inversion by bandshape analysis. The crystal structure of 1,1′-bis(methylthio)ruthenocene tetracarbonyltungsten has been determined. The WS bond lengths are 2.571(5) and 2.565(4) Å, with a SWS bond angle of 81.1(1)°. The cyclopentadienyl rings are eclipsed and the SCH 3 groups adopt a meso relationship.