Opening of the azastibol heterocycle with various acids: Isolation of novel N,C-chelated organoantimony(III) compounds

•Opening of the azastibole ring was achieved by various HX acids.•These reactions yielded variety of N,C-chelated organoantimony(III) compounds.•Compounds were characterized by ESI–MS, NMR spectroscopy and X-ray.

The reaction of N,C-intramolecularly coordinated organoantimony(III) compound L2SbCl (1) (where L is [2-(2′,6′-i-Pr2C6H3)NCHC6H4]) with one molar equivalent of the K-selectride (K[B(s-Bu)3H]) gave compound LSb{2-[CH2N(2′,6′-i-Pr2C6H3)]C6H4} (2) containing five membered aza-stiba heterocycle. On the contrary, analogical reaction between the organobismuth(III) compound L2BiCl (3) and K-selectride gave only inseparable mixture of products. Reactions of 2 with selected acids HX resulted in the cleavage of the present Sb–N bond and formation of novel N,C-chelated compounds LSb(X){2-[CH2NH(2′,6′-i-Pr2C6H3)]C6H4} (where X = Cl (4), CH3COO (5), CF3COO (6), CF3SO3 (7) or FcCOO (8); Fc = ferrocenyl). Compounds 4–8 were characterized by the help of elemental analysis, electrospray ionization (ESI) mass spectrometry, multinuclear NMR spectroscopy, IR spectroscopy and in the case of 5 by the single-crystal X-ray diffraction analysis. The molecular structures of compounds LSb(X){2-[CH2NH(2′,6′-i-Pr2C6H3)]C6H4}·HX (where X = CF3COO (6a), CF3SO3 (7a)) were determined by the single-crystal X-ray diffraction analysis as well. Compounds 6a and 7a are most probably products of partial hydrolysis of compounds 6 and 7.

Graphical abstractThe reaction of azastibole with selected acids HX resulted to the cleavage of the present Sb–N bond and opening of the azastibole ring. Using this synthetic strategy variety of organoantimony(III) compound may be accessible.Figure optionsDownload full-size imageDownload as PowerPoint slide