Hypercoordinated Oligosilanes Based on Aminotrisphenols.

The hypercoordinated silicon chlorides ClSi[(-OCH)N] () and ClSi[(OCHMeCH)N] () were used for the synthesis of catenated derivatives (MeSi)SiSi[(-OCH)N] (), (MeSi)SiSiMeSiMeSi(SiMe)Si[(-OCH)N] (), and (MeSi)SiSi[(OCHMeCH)N] () in reactions with (MeSi)SiK·THF () or (MeSi)SiK·[18-crown-6] (). It was found that the nature of the (MeSi)SiK solvate determines the product of interaction, resulting in the formation of (MeSi)Si(CH)OSi[(OCHMeCH)N] () or . Compounds obtained were characterized using multinuclear NMR and UV-vis spectroscopy and mass spectrometry. The molecular structures of , , and - were investigated by single-crystal X-ray analysis, featuring hypercoordinated Si atoms in a trigonal-bipyramidal coordination environment with O atoms in the equatorial plane. The structure of the side product [N(CHCHMeO)Si]O () was also studied, indicating highly tetrahedrally distorted trigonal-bipyramidal environment at the Si atoms, which was confirmed by crystal density functional theory calculations indicating the very weak Si ← N interaction. The Si···N interatomic distances span a broad range (2.23-2.78 Å). The dependence of structural and NMR parameters for hypercoordinated catenated compounds from the type of the ligand was established.