Tellurium(IV) Tetraalkoxides and Chlorotellurium(IV) Alkoxides Derived from β-Donor Alcohols

Abstract

Keywords: Tellurium / Donor-acceptor systems / Ab initio calculations / X-ray diffraction / NMR spectroscopy Te(OiPr) 3 OCH 2 CH 2 XMe n (1a−1c) and Te(OCH 2 CH 2 NMe 2 ) 4 (2) were synthesised by the reaction of Te(OiPr) 4 with HOCH 2 CH 2 XMe n , while TeCl 2 (OCH 2 CH 2 OMe) 2 (3) and TeCl 3 OCH 2 CH 2 XMe n (4a−4c) resulted from the reaction of TeCl 4 with the corresponding silylated alcohols Me 3 Si-OCH 2 CH 2 XMe n (X = N, n = 2; X = O or S, n = 1). These compounds are the first known representatives of the hitherto unknown classes of tellurium(IV) tetraalkoxides and chlorotellurium(IV) alkoxides derived from β-donor-substituted alcohols. The donor atom X in the alkoxy ligand enables an intramolecular donor-acceptor Te···X interaction, which stabilises the di-and trichlorotellurium alkoxides, but reduces the reactivity of the tellurium atom towards nucleophiles, a result from which an associative-dissociative mechanism was inferred for the nucleophilic substitution in TeCl 4 . In contrast to this, all OiPr ligands of Te(OiPr) 4 can be exchanged by reaction with HOCH 2 CH 2 XMe n . As was shown by multinuclear NMR studies, the kinetics and equilibrium of the reaction of Te(OiPr) 4 with HOCH 2 CH 2 XMe n depend substantially on X and thus demonstrate the presence of Te···X interactions in solution. The molecular and crystal structure of 3 was investigated by single-crystal X-ray diffraction. In the solid state of 3, two kinds of molecules are