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

Three novel tetraorganotin(IV) compounds of general formula L 3 SnR [where i ) L is L CN 2-( N , N -dimethylaminomethyl)phenyl- and R =  n -Bu ( 1 ), Ph ( 2 ); and ii ) L is L NCN 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 L 3 SnX [where i ) L is L NCN with X = OH ( 4 ), and ii ) L is L CN and X = Br ( 5 ), F ( 5b ), Cl ( 5c )]. Several methods were applied to reach the target L 3 SnX molecules including the reactions of 1 or 2 with bromine, iodine or hydrohalic acids in various media, Kocheshkov reactions or transmetallation with HgCl 2 , 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 L 4 C N Sn with SnBr 4 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 [ L 3 C N Sn(H 2 O)] + Br − ( 5a ). All prepared organotin(IV) compounds bearing both L CN and L NCN 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.