Synthesis and structural characterisation of new copper-tellurium clusters: TeBu(n)(SiMe(3)) as a source of RTe(-) and Te2- ligands

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 Te2- 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: [Co-6(mu(3)-Te)(8)(PPh(2)Pr(n))(6)] 1, [Cu-11(mu(3)-TeBu(n))(7)(mu(4)-TeBu(n))(2)(mu(7)-Te)(PPh(3))(5)] 2, [Cu-18(mu(3)-TeBu(n))(6)Te-6(PPr3n)(8)] 3, [Cu58Te32(PPh(3))(16)] 4 and [Cu23Te13(PEt(3))(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 Co-3 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.