Syntheses and Structures of Zinc(tmeda)bis(aryltellurolato) and its Facile Chalcogenospecific Ligand Exchange Reactivity

Abstract

Anaerobic treatment of Zn(tmeda)Br2, where tmeda denotes N,N,N′,N′‐tetramethylethylenediamine, with a solution of Na(TeAr), sodium aryltellurolate, in ethanol in a 1:2 stoichiometry led to the formation of highly air sensitive Zn(tmeda)(TeAr)2 (1–3), while a 1:1 stoichiometry afforded Zn(tmeda)Br(TeAr) (4). Crystallography revealed all complexes to be monomeric with four coordinate central zinc atoms bound to tmeda and two TeAr, or a TeAr and a Br ligand. Upon mixing two symmetrically substituted Zn(tmeda)(TeAr)2 complexes in solution, 125Te NMR revealed a facile ligand exchange providing Zn(tmeda)(TeAr)(TeAr′). In addition, Zn(tmeda)(TeAr)(TeAr′) complexes form on mixing symmetric Zn(tmeda)(TeAr)2 complexes and (TeAr′)2. The lability of the zinc complexes was put to advantage in ligand‐substitution reactions wherein treatment of SnCl4 with Zn(tmeda)(TeAr)2 affords Sn(TeAr)4 in excellent yields without the concurrent formation of the redox product (TeAr)2. The apparent lability of the Zn–Te bond prevented the volatilization of 1–3 for their use as chemical vapor deposition precursors for the fabrication of ZnTe thin films. On heating, to volatize the complexes, the complexes decompose to cubic ZnTe and TeAr2 sublimes from the samples. Thermal gravimetric analysis indicates the loss of tmeda followed by the loss of TeAr2.