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

The tetraorgano- and triorgano-halotin compounds Me₃(8-Me₂NC₁₀H₆)Sn and RR′(8-Me₂NC₁₀H₆)SnX (R = R′ = Me or Ph, X = Cl or Br and R = Me, R′ = Ph, X = Br) have been obtained from the sol1 1 reaction of 8-dimethylamino-1-naphthyl-lithium (8-Me₂NC₁₀H₆Li) with the relevant organotin halide (Me₃SnCl or RR′SnX₂). On the basis of the ¹H NMR data a trigonal bipyramidal structure with intramolecular Sn-N coordination is proposed for the RR′(8-Me₂NC₁₀H₆)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-Me₂NC₁₀H₆)SnBr has considerable configuration stability (at least on the NMR timescale, 60 MHz): the Me groups of the coordinated NMe₂ group remain diasetereotopic up to at least 120°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 Me₃SnX with Me₃(8-Me₂NC₁₀H₆)Sn results in quantitative formation of Me₄Sn and Me₂(8-Me₂NC₁₀H₆)SnX (X = Cl, Br). Overcrowding in the 8-Me₂N-1-Me₃SnC₁₀H₆ 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-Me₂N-1-Me₃SnC₁₀H₆ also leads to quantitative formation of MePtCl(COD) from PtCl₂(COD) at room temperature.