874015-73-3Relevant academic research and scientific papers
Switching between penta- and hexacoordination with salen-silicon-complexes
Wagler, J?rg,B?hme, Uwe,Brendler, Erica,Thomas, Berthold,Goutal, Sigrid,Mayr, Herbert,Kempf, Bernhard,Remennikov, Grigoriy Ya.,Roewer, Gerhard
, p. 4270 - 4286 (2005)
The reaction between phenyltrichlorosilane and the tetradentate ligands o-HO-C6H4-C(CH3)=N-(CH2) n-N=C(CH3)-o-C6H4-OH (n = 2, 3, 4), supported by an amine base, yields pentacoordinate silicon complexes (C 6H5)Si-[o-O-C6H4-C(CH 3=)N-(CH2)n-N-C(=CH2)-o-C 6H4-O] with enamine functionalized ligands. This reaction pattern can be transferred onto various ligands of 2-iminomethylphenolate-type. The resulting pentacoordinate silicon complexes react with a variety of Br?nsted acids HY to yield hexacoordinate salen silicon complexes (C 6H5)(Y)Si-[o-O-C6H4-C(CH 3)=N-(CH2)n-N=C(CH3)-o-C 6H4-O] (Y = benzoate, picrate, 8-oxyquinolinate, 2-oxy-1,4-naphthoquinonate, p-tert-butylphenolate, (5-phenyltetrazol)-2-ide, fluoride, tetrafluoroborate). Hexacoordination of their Si-atoms was confirmed by 29Si NMR spectroscopy and, in some cases, by X-ray crystal structure analysis. Examples for similarities and differences in the coordination behavior of the silicon atom and its heavier congeners (Ge, Sn) in the salen-type coordination sphere as well as data regarding the nucleophilicity of some of these novel enamine complexes are presented.
