210633-18-4Relevant academic research and scientific papers
Nucleophilic attack within Ge, Sn and Pb complexes containing Me2N(CH2)3 - As a potential intramolecular donor ligand
Zickgraf, Andrea,Beuter, Mike,Kolb, Ute,Dra?ger, Martin,Tozer, Ramon,Dakternieks, Dainis,Jurkschat, Klaus
, p. 203 - 214 (1998)
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, Cl, 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)3SnPh2Cl,5;Me 2N(CH2)3SnPh2Br,5a;Me 2N(CH2)3SnPh2I,5b;Me 2N(CH2)3SnPh2OPh,5d;Me 2N(CH2)3SnPh3·HCl·H2O, 1a; Me2N(CH2)3PbPh2I, 17b), and by solution 13C, 119Sn and 207Pb NMR data. This nucleophilic attack originates from the π-basicity and the charge flow from the ligands into a σ*-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>Ph3 and Ph2I>Ph2Br>Ph2OPh>Ph 2Cl>Ph2F hold for an increasing approach (N?Ge/Sn/Pb). The δ values (13C) of the α-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 119Sn NMR chemical shifts and spin-spin coupling constants is given, which supports the arguments on the basis of interactions of frontier orbitals.
