Cadmium complexes of the tripodal [Te(N-t-Bu)3]2– dianion and the HgCl2 adduct of a tellurium diimide dimer

Abstract

The reactions of CdCl2 or HgCl2 with {Li2[Te(N-t-Bu)3]}2 in n-hexane–THF give rise to two distinctly different types of product. In the former case the complexes [Li(THF)x][(CdCl)3{Te(N-t-Bu)3}2] (7a (x = 4), 7b (x = 3)) are obtained. The tetrasolvated complex 7a is a solvent-separated ion pair. The trisolvated complex 7b is a contact ion pair in which the fourth coordination site at the Li+ centre is occupied by one of the Cl ligands of the anion. The polycyclic anion in 7a and 7b is comprised of two tripodal [Te(N-t-Bu)3]2– dianions that exhibit different coordination modes to the three CdCl+ units. One ligand is N,N′-chelated to all three metal centres, and each nitrogen atom bridges two Cd atoms, whereas the other is bonded in a tris-N-monodentate fashion in 7b. In 7a there is an additional weak Cd-N interaction. The reaction of HgCl2 with {Li2[Te(N-t-Bu)3]}2 produces the adduct [t-BuNTe(µ-N-t-Bu)2TeN-t-Bu]HgCl2 (8), in which the dimeric tellurium diimide ligand in its cis(exo,exo) configuration is N,N′-chelated to mercury. Polymeric strands parallel to the b axis are formed by weak Te•••Cl interactions (3.5248(16) Å, 3.5876(15) Å) involving both Cl atoms, but only one Te atom of the ligand. Key words: imido ligands, cadmium, mercury, tellurium.