Adducts of a sterically hindered tellurium(iv) catecholate with diimines

Abstract

Adducts of sterically hindered tellurium catecholate Te(Cat³⁶)₂ (Cat³⁶ = 3,6-di-tert-butyl-catecholate) with diimine ligands were isolated and characterized by means of single crystal X-ray diffraction along with IR, UV-vis-NIR and NMR (¹H, ¹²⁵Te) spectroscopy. Adducts with 1,10-phenanthroline (phen) and 5,6-epoxy-5,6-dihydro-[1,10]phenanthroline (phenO) feature a very rare μ-κ²N,N′:κ²N,N′-bridging coordination mode of diimines. The adduct with 2,2′-bipyrimidine (bpm) is dimeric with a μ-κ²N,N′:κ²N,N′-bridging coordination mode of bpm, while with 4,7-dimethyl-1,10-phenanthroline (phenMe₂) a dimer is formed due to Te-(η⁶-C₆) contacts. Te⋯N and Te⋯C interactions between Te(Cat³⁶)₂ and the diimines were found to be attractive and non-covalent (DFT and QTAIM). In accordance with the weakness of Te⋯N interactions, no ligand-to-ligand charge transfer (LLCT) bands were observed in the electronic spectra of the adducts.