Pentacoordinate [8-dimethylamino)napthyl]diorganotin halides containing a rigid, flat NCCCSn chelate ring. An unexpected redistribution reaction between [8-dimethylamino)naphthyl] trimethyltin and trimethyltin halide

Abstract

The tetraorgano- and triorgano-halotin compounds Me{3}(8-Me{2}NC{1}{0}H{6})Sn and RR'(8-Me{2}NC{1}{0}H{6})SnX (R = R' = Me or Ph, X = Cl or Br and R = Me, R' = Ph, X = Br) have been obtained from the sol11 reaction of 8-dimethylamino-1-naphthyl-lithium (8-Me{2}NC{1}{0}H{6}Li) with the relevant organotin halide (Me{3}SnCl or RR'SnX{2}). On the basis of the }1{H NMR data a trigonal bipyramidal structure with intramolecular Sn-N coordination is proposed for the RR'(8-Me{2}NC{1}{0}H{6})SnX compounds, in which the organo ligands occupy the equatorial and the N and X atoms the axial positions. The Sn center in chiral MePh(8-Me{2}NC{1}{0}H{6})SnBr has considerable configuration stability (at least on the NMR timescale, 60 MHz): the Me groups of the coordinated NMe{2} group remain diasetereotopic up to at least 120}o{C. This relatively high stability is ascribed to the fixed position of the Sn and N atoms respectively connected to the 1- and 8-positions of the flat naphthyl ring. Reaction of Me{3}SnX with Me{3}(8-Me{2}NC{1}{0}H{6})Sn results in quantitative formation of Me{4}Sn and Me{2}(8-Me{2}NC{1}{0}H{6})SnX (X = Cl, Br). Overcrowding in the 8-Me{2}N-1-Me{3}SnC{1}{0}H{6} compound as well as the formation of the Sn-N bond are suggested as driving forces for this Me/Cl exchange reaction. This methylating property of 8-Me{2}N-1-Me{3}SnC{1}{0}H{6} also leads to quantitative formation of MePtCl(COD) from PtCl{2}(COD) at room temperature.