Organotellurium(II) and ‐(IV) Compounds with Picolinoylbis(thioureas): From Simple 1 : 1 Adducts to Multimetallic Aggregates

Abstract

Reactions of 2,6‐dipicolinoylbis(N,N‐diethylthiourea) (H2LEt) with common tellurium(IV) starting materials such as PhTeBr3 or TeBr4 yield various tellurium(IV) and tellurium(II) compounds depending on the conditions applied. Equimolar amounts of H2LEt and PhTeBr3 give the 1:1 complex [PhTeIVBr3(H2LEt)], while with an excess of H2LEt, the tellurium compound is partially reduced and a {PhTeII}+ building block coordinates to both sulfur atoms of H2LEt under formation of the ion pair [PhTeII(H2LEt)][PhTeIVBr4]. Similar reactions between H2LEt and TeBr4 give the neutral monomer [TeIIBr2(H2LEt)] or the coordination polymer [TeIIBr2(H2LEt)]∞. The latter compound is also formed with the assistance of Pb2+ ions. While the lead ions do not appear in the isolated product, similar reactions with transition metal ions such as Ni2+, Mn2+, or Co2+ result in the formation of hetero­bimetallic complexes, in which Te(II) building blocks are directed to the sulfur atoms of the deprotonated ligand {H2LEt2‐S,S}2‐, while the transition metal ions occupy central coordination positions between two of the organic ligands using the pyridine nitrogen atom, carbonyl oxygen atom(s) and/or the nitrogen atoms of the thiourea units.