Synthesis and crystal and molecular structure of bis(trimethylsilyl-methylidyne)tetrakis(trimethylsilylmethyl)dirhenium (Re–Re)

Abstract

The complex Re₂(µ-CSiMe₃)₂(CH₂SiMe₃)₄ has been isolated as green crystals in small yield from the reaction of ReCl₄(thf)₂(thf = tetrahydrofuran) with Me₃SiCH₂MgCl and characterised by X-ray diffraction analysis. Crystals are triclinic, space group P, with a= 10.312(2), b= 10.703(6), c= 11.625(5)Å, α= 117.04(4), β= 64.71(3), and γ= 115.89(3)°. The structure was determined using observed data and refined to an R of 0.0376. The molecule has (C_i) symmetry with a planar, central Re₂C₂ ring. The carbyne ligands bridge symmetrically with the Re–C multiple bond component delocalised. The Re–Re distance of 2.557 Å is rather long, but is still considered compatible with a metal–metal double bond.