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Thirteen tin compounds LxPhySnClz and LPh2SnPhX (x = 1 - 4 , y = 0-3, z = 0-2; X = Ph, F, Cl, Br, I, OPh), six germanium compounds LxPhyGeClz and four lead compounds LPh2PbPhX (X = Ph, C1, Br, I) containing the potential intramolecular donor L = Me2N(CH2)(3) - have been synthesized by Grignard reactions, redistribution, halogenation, exchange of halide and phenylation. Evidence for 1,5-chelation in which the donor Me2N intramolecularly attacks the Lewis-acidic atoms Ge, Sn or Pb is provided b...Thirteen tin compounds LxPhySnClz and LPh2SnPhX (x = 1 - 4 , y = 0-3, z = 0-2; X = Ph, F, Cl, Br, I, OPh), six germanium compounds LxPhyGeClz and four lead compounds LPh2PbPhX (X = Ph, C1, Br, I) containing the potential intramolecular donor L = Me2N(CH2)(3) - have been synthesized by Grignard reactions, redistribution, halogenation, exchange of halide and phenylation. Evidence for 1,5-chelation in which the donor Me2N intramolecularly attacks the Lewis-acidic atoms Ge, Sn or Pb is provided by six crystal structure determinations: Me2N(CH2)(3)SnPh2Cl, 5; Me2N(CH2)(3)SnPh2Br, 59; Me2N(CH2)(3)SnPh2I, 5b; Me2N(CH2)(3)SnPh2OPh, 5d; Me2N(CH2)(3)SnPh3 . HCl . H2O, 1a; Me2N(CH2)(3)PbPh2I, 17b), and by solution C-13, Sn-119 and Pb-207 NMR data. This nucleophilic attack originates from the pi-basicity and the charge flow from the ligands into a sigma*-LUMO at Ge, Sn or Pb. The electronegativity of the ligands at Ge, Sn or Pb inhibits nucleophilic attack. The ligand sequences PhCl2 > Ph2Cl > PhCl > Ph-3 and Ph2I > Ph2Br > Ph2OPh > Ph2Cl > Ph2F hold for an increasing approach (N ... Ge/Sn/Pb). The delta values (C-13) Of the alpha-methylene in CDCl3 solution are shifted distinctly to high frequency by increasing the approach between the Me2N donor and the central atom. A qualitative discussion of Sn-119 NMR chemical shifts and spin-spin coupling constants is given, which supports the arguments on the basis of interactions of frontier orbitals. (C) 1998 Elsevier Science S.A. All rights reserved. » weiterlesen» einklappen

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