Tetraaryl-methane analogues in group 14 -: V.: Distortion of tetrahedral geometry in terms of through-space π-π and π-σ interactions and NMR sagging in terms of λ-σ* charge transfer

被引：10

作者：

Charissé, M

Zickgraf, A

Stenger, H

Bräu, E

Desmarquet, C

Dräger, M ^{[1
]}

Gerstmann, S

Dakternieks, D

Hook, J

机构：

[1] Univ Mainz, Inst Anorgan Chem & Analyt Chem, D-55099 Mainz, Germany

[2] Deakin Univ, Fac Sci & Technol, Sch Biol & Chem Sci, Geelong, Vic 3217, Australia

[3] Univ New S Wales, NMR Facil, Sydney, NSW 2052, Australia

来源：

POLYHEDRON | 1998年 / 17卷 / 25-26期

关键词：

silicon; germanium; tin; lead; through-space interaction; heteronuclear NMR in solution and solid state; pi-sigma* charge transfer;

D O I：

10.1016/S0277-5387(98)00256-3

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

44 members of the compound series Ph4-nMRn (M = Si, Ge, Sn, Pb; R = o-, m-, p-Tol: n = 0-4) were synthesized (15 new compounds). The crystal structures of Ph3Sn(o-Tol) and PhSn(o-Tol)(3) were determined and compared to 16 known n structures. Subject to the distance d(M-C), an interplay between through-space pi-pi repulsion and pi-sigma attraction leads to either elongated or compressed tetrahedral geometry. Si-29-, Sn-119- and Pb-307-NMR chemical shifts were determined in solution and in the solid state. Ge-73 chemical shifts were measured only in solution. An upfield or downfield sagging of the chemical shifts along each series is rationalized in terms of a pi-sigma* charge transfer which is constrained by torsion of the aromatic groups. (C) 1998 Elsevier Science Ltd. All rights reserved.

引用

页码：4497 / 4506

页数：10

共 29 条

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