Syntheses, solid-state structures, solution behavior of hypervalent organobismuth(III) compounds [2-(Et2NCH2)C6H4]nBiX3−n and DFT characterization of [2-(Me2NCH2)C6H4]nBiX3−n [X = Cl, Br, I; n = 1–3]

The reaction of RLi [R = 2-(Et2NCH2)C6H4] with BiCl3 in 3:1 or 2:1 molar ratio afforded R3Bi (1) and R2BiCl (2), respectively. Redistribution reactions between 1 and BiCl3 (1:2 molar ratio) resulted in RBiCl2 (5). R2BiBr (3) formed from RMgBr and BiCl3 (2:1 molar ratio). R2BiI (4) and RBiX2 [X = Br (6), I (7)] were obtained from 2 and 5 by halogen-exchange reactions using KX in water/CH2Cl2 mixture. Compounds 1–7 were characterized by FT-Raman/IR, 1H and 13C NMR spectroscopies as well as mass spectrometry. The structures of 1–4 were determined by single-crystal X-ray diffraction. They all have pyramidal C3Bi or C2BiX cores. For R3Bi (1) intramolecular N → Bi interactions of medium strength [Bi(1)–N(1) 3.214(7) Å] result in an overall distorted octahedral (C,N)3Bi core. In the monohalides 2–4 one nitrogen is strongly coordinated to bismuth trans to the halogen [range 2.571(8)–2.645(6) Å], while the second one is involved in a considerably weaker intramolecular N → Bi interaction trans to a carbon atom [range 2.992(12)–3.170(8) Å]. The overall (C,N)2BiX (X = Cl, Br, I) core is distorted square-pyramidal. The NMR studies provided evidence for the presence of internal nitrogen-bismuth coordination in solution for RBiX2 species. DFT calculations were performed on the related compounds R′BiX2 [X = Cl (8), Br (9), and I (10)], R′2BiX [X = Cl (11), Br (12), and I (13)], and R′3Bi (14) [R′ = 2-(Me2NCH2)C6H4] in order to elucidate the bond nature and vibrational spectroscopic features of this class of organobismuth(III) compounds.

The pendant arm aryl bismuth(III) compounds [2-(Et2NCH2)C6H4]nBiX3−n (n = 1–3, X = Cl, Br, I) were synthesized and characterized both in solid state and in solution. The solid-state structures resemble those of the analogous compounds with methyl groups at the nitrogen atom of the pendant arm. NMR spectra revealed the presence of internal nitrogen-bismuth coordination in solution. DFT calculations allowed to investigate the nature of the chemical bond in the title systems and their vibrational properties.Figure optionsDownload as PowerPoint slide