Thallium(i) complexes of dichalcogenido imidodiphosphinates {Tl[(EPiPr2)2N]}n (E = Te, Se, S): Synthesis, NMR spectra and a structural comparison

Abstract

The homoleptic thallium(I) complexes {Tl[(EPⁱPr₂)₂N]}_n (3a, E = Te; 3b, E = Se; 3c, E = S) have been obtained in 70-86% yields from the reaction of TlOEt with (TMEDA)Na[(EPⁱPr₂)₂N] in CH₂Cl₂ or Et₂O. Complexes 3a-c were structurally characterised in the solid state by single crystal X-ray diffraction and in solution by multinuclear NMR spectroscopy (³¹P, ⁷⁷Se, and ¹²⁵Te). The solid-state structures of 3a, 3b and 3c are comprised of one-dimensional coordination polymers. In 3a and 3b there are two distinct environments for both the thallium centres and the [(EPⁱPr₂)₂N]⁻ ligands. The denticities of the selenium centres in the ligands of 3b differ significantly from those of tellurium donor atoms in 3a giving rise to different coordination geometries at the chalcogen atoms in these two complexes; however, both possess edge-sharing Tl₂E₄ octahedra as structural units. By contrast, the sulfur analogue 3c exhibits only one ligand environment with trigonal pyramidal geometries for both sulfur centres and a distorted tetrahedral geometry for thallium generating vertex-sharing four-membered Tl₂S₂ rings.