Synthesis, structures, and reactivities of some pentamethylcyclopentadienyl–sulphur compounds

Abstract

The pentamethylcyclopentadienyl–sulphur compounds S(C₅Me₅)₂(1) and S₂(C₅Me₅)₂(2) have been prepared by the reaction of Li(C₅Me₅) with SCL₂ and S₂Cl₂, respectively. Compounds (1) and (2) were characterised by n.m.r. and mass spectroscopy. The X-ray crystal structure of (1) has been determined. Compound (1) crystallises in the monoclinic space group P2₁/c(no. 14), with a= 10.375(2), b= 11.274(2), c= 16.132(9)Å, β= 91.92(3)°, and Z= 4. The reaction of (1) with [Fe₂(CO)₉] results in the known cluster compound, [Fe₃S₂(CO)₉](3), the identity of which was confirmed by X-ray crystallography. Unsuccessful attempts were made to prepare cations of the type [S(C₅Me₅)₂]ⁿ⁺ by (i) oxidation of (1) and (2), or (ii) the reaction of S(C₅Me₅)Cl (prepared in situ) with Al₂Cl₆. Cyclic voltammetric experiments on (1) and C₅Me₅H suggest that oxidation occurs at the carbocyclic ring rather than at the sulphur atom.