Heterocyclic bismuth(III) compounds with transannular S→Bi interactions. An experimental and theoretical approach

Abstract

Several new diorganobismuth(III) compounds based on a butterfly-like tetrahydro-dibenzo[c,f][1,5] thiabismocine heterocyclic framework were prepared and structurally characterized. The reaction between the dilithio derivative of bis(2-bromobenzyl)sulfane with BiBr3 in a 1:1 M ratio resulted in the formation of [(C6H4CH2)2S]BiBr (1). Further exchange reactions of 1 with KI, AgNO3 and AgOSO2CF3, respectively, afforded the hypervalent species [(C6H4CH2)2S]BiX [X = I (2), ONO2 (3) and OSO2CF3 (4)]. The new species were characterized by 1H and 13C NMR, FT IR spectroscopy and mass spectrometry. The crystal and molecular structures of compounds 1–4 were determined by single-crystal X-ray diffraction. In all compounds the sulfur atom is strongly intramolecularly coordinated to bismuth, thus resulting in hypervalent species 10-Bi-4 (for 1 and 2) and 12-Bi-5 (for 3 and 4). Intermolecular interactions (X…Hmethylene in 1 and 2, Bi…Cg in 3 and Bi…O in 4) led to polymeric chains in the crystals. DFT calculations were carried out on [(C6H4CH2)2S]BiCl and 1–4 in order to better understand the S→Bi intramolecular coordination.