Octahedral coordination complexes of tellurium tetrachloride

Abstract

The reaction between TeCl 4 and two equivalents of OPPh 3 affords crystals of the coordination complex [TeCl 4(OPPh 3) 2], which has been characterized by X-ray crystallography. The coordination geometry around the tellurium centre is close to regular octahedral, with little evidence of any lone pair stereochemical activity, and the oxygen donor atoms are cis. A similar reaction involving the chelating ligand dppmS 2 [Ph 2P(S)CH 2P(S)Ph 2] afforded the complex [TeCl 4(dppmS 2)], which was also characterized by X-ray crystallography and found to be similar in most respects to the OPPh 3 complex. However, large thermal ellipsoids associated with the two chlorines trans to the sulphur atoms are interpreted in terms of the onset of lone pair stereochemical activity. Attempted preparations of a 4-picoline adduct of TeCl 4 and an SPPh 3 adduct of SeCl 4 resulted in the complexes [4-picolinium] 2[TeCl 6] and [Ph 3PSH] 2[Se 2Cl 6] respectively, both of which were characterized by X-ray crystallography.