Synthesis and Structural Characterization of Heteroboroxines with MB2O3 Core (M = Sb, Bi, Sn)

Reaction of organoantimony and organobismuth oxides (LSbO)2 and (LBiO)2 (where L is [2,6-bis­(dimethylamino)­methyl]­phenyl) with four equivalents of the organoboronic acids gave new heteroboroxines LM­[(OBR)2O] 1a–2c (for M = Sb: R = Ph (1a), 4-CF3C6H4 (1b), ferrocenyl (1c); for M = Bi: R = Ph (2a), 4-CF3C6H4 (2b), and ferrocenyl (2c)). Analogously, reaction between organotin carbonate L­(Ph)­Sn­(CO3) and two equivalents of organoboronic acids yielded compounds L­(Ph)­Sn­[(OBR)2O] (where R = Ph (3a), 4-CF3C6H4 (3b), and ferrocenyl (3c)). All compounds were characterized by elemental analysis and NMR spectroscopy. Their structure was described both in solution (NMR studies) and in the solid state (X-ray diffraction analyses 1a, 1c, 2b, 3b, and 3c). All compounds contain a central MB2O3 core (M = Sb, Bi, Sn), and the bonding situation within these rings and their potential aromaticity was investigated by the help of computational methods.