Synthesis and structure of pentacoordinated monoorganosilane derivatives of pyridine ligands

The reaction of 2,6-disubstituted pyridines with bis(dimethylamine)dimethylsilane, dichlorophenylmethylsilane and dichlorodiphenylsilane yielded the monomeric silanes: 2,6-pyridinebis(1,1-di-p-bromophenylmethoxy)dimethylsilane (9a), 2,6-pyridinebis(1,1-di-p-tert-butylphenylmethoxy)dimethylsilane (9b), 2,6-pyridinebis(1,1-diphenylethoxy)methylphenylsilane (12a) and 2,6-pyridinebis(1,1-adamantylethoxy)diphenylsilane (12b). The ²⁹Si-NMR data for these compounds confirmed the presence of N→Si bonds and the variable temperature NMR study of 12a and 12b showed the existence of a fluxional behavior for the 2,6-diethoxypyridine derivatives, additionally the X-ray diffraction study of 9a showed that in this compound the silicon atom adopts a square pyramidal geometry. Moreover, 1,3,10,12-tetraoxo-2,11-(dimethylsilylene)[5.5]paracyclophane (10) was synthesized from 1,4-benzenedimethanol and its structure established by X-ray crystallographic analysis showing that the aromatic rings are not perfectly eclipsed.