Synthesis and structural characterisation of new copper–tellurium clusters: TeBun(SiMe3) as a source of RTe– and Te2– ligands

Abstract

Reactions of cobalt(II) and copper(I) salts with the functionalised reagents alkyl- and aryl-(trimethylsilyl)tellurium have been explored. The silylated reagents are found to be an excellent source of RTe^– and Te^2– ligands alike in high-nuclearity transition metal–tellurium clusters and the products isolated from the reaction mixtures have been structurally characterised by single-crystal X-ray analyses: [Co₆(µ₃-Te)₈(PPh₂Prⁿ)₆]1,[Cu₁₁(µ₃-TeBuⁿ)₇(µ₄-TeBuⁿ)₂(µ₇-Te)(PPh₃)₅]2,[Cu₁₈(µ₃-TeBuⁿ)₆Te₆(PPrⁿ₃)₈]3,[Cu₅₈Te₃₂(PPh₃)₁₆]4 and [Cu₂₃Te₁₃(PEt₃)₁₂]5 have been synthesised. The formation of the complexes is highly dependent on the ancillary phosphine used. Cluster 1 consists of a non-bonded octahedral array of Co atoms with eight tellurium ligands capping the open Co₃ faces. Complexes 2–4 possess layered structures composed of Te atoms with Cu occupying peripheral and interlayer sites. The Te atoms in 5 form a body-centred icosahedron, with an overall near-spherical cluster framework.