NCN‐Chelated Organoantimony(III) and Organobismuth(III) Phosphonates: Syntheses and Structures

The reactions of the organoantimony and organobismuthoxides [LSbO]2 (1) and [LBiO]2 (2), where L = [2,6‐(Me2NCH2)2C6H3]–, with selected organophosphonic acids in a 1:4 molar ratio gave molecular organoantimony and organobismuth phosphonates LM[OP(R)(O)(OH)]2 [M = Sb, R = Et (3), Ph (4), tBu (5); M = Bi, R = tBu (8)]. Similarly, the reactions of 1 and 2 with tBuP(O)(OH)2 in a 1:2 molar ratio resulted in LM[O2P(tBu)(O)] [M = Sb (6), M = Bi (9)]. Reactions of 6 and 9 with EtP(O)(OH)2 yielded mixed phosphonates LM[OP(Et)(O)(OH)][OP(tBu)(O)(OH)] [M = Sb (7), M = Bi (10)]. All compounds were characterized by elemental analysis, ESI mass spectrometry, 1H, 13C and 31P NMR spectroscopy and IR spectroscopy. Molecular structures of compounds 4, 5, 8 and 9 were determined by using X‐ray single‐crystal diffraction in the solid state. Secondary phosphonates 4, 5 and 8 form weakly bonded dimeric units through hydrogen bridges of the type PO–H···O=P. On the other hand, compound 9 is trimeric in the solid state with the central 12‐membered ring formed by three LBi[O2P(tBu)(O)] building blocks through intermolecular Bi···O=P contacts.