Room-Temperature Insertion of Elemental Tellurium into the Csp3−Br and −I Bonds of α-Bromo- and α-Iodopinacolone

Pinacolyltellurium(IV) dihalides, (t-BuCOCH2)(2)TeX2 (X = Br (1b), I (1c)) and Ar(t-BuCOCH2)TeCl2 (Ar = 1-C10H7 (Np) (2a), 2,4,6-Me3C6H2 (Mes) (3a)), are readily prepared at room temperature by the oxidative insertion of elemental tellurium into the C-sp(3)-Br or -I bond of the alpha-halopinacolone and by the reaction of ArTeCl3 with the pinacolone t-BuCOCH3. The bromides Np(t-BuCOCH2)TeBr2 (2b) and Mes(t-BuCOCH2)TeBr2 (3b) can be prepared by the addition of bromine to the telluride Ar(t-BuCOCH2)Te or of alpha-bromopinacolone to ArTeBr. Variable-temperature H-1 and C-13 NMR of the separate signals for the o-Me groups in 3a, b indicate a very high barrier to rotation about the Te-C(aryl) bond. Crystal diffraction data for 1c, 2a-c, and 3b show that intramolecular 1,4-Te center dot center dot center dot O(C) secondary bonding interactions (SBIs) are retained even in the presence of bulky aryl groups and intermolecular Te center dot center dot center dot X SBIs are subject to electronic population and steric congestion around the Te(IV) center in the solid state.