Sterically Hindered Tellurium(IV) Catecholate as a Lewis Acid

Sterically hindered tellurium catecholate Te­(Cat36)2 (Cat36 = 3,6-di-tert-butyl-catecholate) was synthesized with the reaction of amorphous Te with 3,6-di-tert-butyl-o-benzoquinone. Adducts of Te­(Cat36)2 with various O- and N-donors were isolated and characterized by means of single-crystal X-ray diffraction along with IR, UV–vis, and NMR (1H, 13C, and 125Te) spectroscopies. In the crystal structure of the adduct with 2,2′-bipyridine (bipy), the unprecedented μ-κ2N,N′:κ2N,N′-bridging coordination mode of bipy was observed. Various intermolecular interactions Te...O, Te...N, and Te...C in adducts were analyzed using density functional theory calculations and quantum theory of atoms in molecules analysis. The estimated strength for appropriate short contacts varies from 0.9 to 5.3 kcal/mol, and they are attractive and purely non-covalent.