Quest for triorganotin(IV) compounds containing three C,N- and N,C,N-chelating ligands

Three novel tetraorganotin(IV) compounds of general formula L3SnR [where i ) L is LCN 2-(N ,N -dimethylaminomethyl)phenyl- and R = n -Bu (1), Ph (2); and ii ) L is LNCN 2,6-bis-(N ,N -dimethylaminomethyl)phenyl- with R = n -Bu (3)] were synthesized. These species were used as potential precursors for the target preparation of some triorganotin(IV) species of general formula L3SnX [where i ) L is LNCN with X = OH (4), and ii ) L is LCN and X = Br (5), F (5b), Cl (5c)]. Several methods were applied to reach the target L3SnX molecules including the reactions of 1 or 2 with bromine, iodine or hydrohalic acids in various media, Kocheshkov reactions or transmetallation with HgCl2, but the composition of all reaction mixtures was not satisfactory towards the target. Compound 4 has the monomeric structure with OH group interacting with one of the nitrogen atoms via H-bridge. Target compound 5 was prepared by the reaction of three equivalents View the MathML sourceL4CNSn with SnBr4 followed by the isolation of 5 from the reaction mixture based on different solubility of 5 in various solvents. Surprisingly, the presumably air-stable 5 can easily ionize in the air to give a novel aqua-complex [View the MathML sourceL3CNSn(H2O)]+Br− (5a). All prepared organotin(IV) compounds bearing both LCN and LNCN ligands were characterized by multinuclear NMR spectroscopy and, when eligible, by the elemental analysis. In addition, the solid-state structures of 1, 2, 4, 5a, 6, 8 and 9 were determined by the X-ray diffraction analysis.