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Tellurium(IV) Tetraalkoxides and Chlorotellurium(IV) Alkoxides Derived from β‐Donor Alcohols
Author(s) -
Fleischer Holger,
Dienes Yvonne,
Schollmeyer Dieter
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200208)2002:8<2073::aid-ejic2073>3.0.co;2-8
Subject(s) - chemistry , intramolecular force , nucleophile , associative substitution , tellurium , reactivity (psychology) , molecule , crystallography , ligand (biochemistry) , intermolecular force , stereochemistry , catalysis , inorganic chemistry , organic chemistry , medicine , biochemistry , alternative medicine , receptor , pathology
Te(O i Pr) 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(O i Pr) 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 SiOCH 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 O i Pr ligands of Te(O i Pr) 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(O i Pr) 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 present, differing in the coordination modes of the Te atoms. In each molecule, two intramolecular dative Te ··· O bonds [264.3(2)−267.7(2) pm] exist, approximately trans to the covalent Te−O bonds. Two C 1 ‐symmetric molecules are linked by intermolecular Te ··· Cl contacts to a third, namely the C 2 ‐symmetric molecule, giving coordination numbers of six and seven for the Te atoms of the C 2 ‐ and C 1 ‐symmetric moieties, respectively. Ab initio (MP2/LANL2DZP) geometry optimizations and thermochemical calculations of the model compounds TeCl 3 OCH 2 CH 2 XH n ( 4α − 4γ ) and Te(OH) 3 OCH 2 CH 2 XH n ( 1α − 1γ ) as well as an analysis of the bonds in terms of natural bond orbitals were performed in order to study the nature of the Te ··· X bond and its dependence on conformational restraints. The donor power of the N atom was found to be greater than those of the O and S atoms and the Te ··· X interactions are stronger for TeCl 3 OCH 2 CH 2 XH 2 than for Te(OH) 3 OCH 2 CH 2 XH 2 ; σ‐type n(X)−σ*(Te−E) interactions are important for the Te ··· X bond and compete with π‐type n(O)−σ*(Te−E) interactions, which in turn are of importance for the E−Te−O−C conformation (E = O, Cl). (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)