The synthesis and NMR spectra of new pentacoordinate silicon compounds, (OSi)- and (ClSi)-chloro[1-(1,1-dimethyl-2-acylhydrazonium)methyl]dimethylsilanes and (OSi)chloro-[2-(1,1-dimethyl-2-acylhydrazino)methyl]dimethylsilanes

Abstract

Pentacoordinate silicon compounds containing a “chelate” six-membered silacarbofunctional ring, such as the chloro[1-(1,1-dimethyl-2-acylhydrazonium)methyl]-dimethylsilanes, Me 2Cl SiCH 2NMe 2NC(O) R with R = CF 3 (Ib), C 6H 5 (Ic), 4′-MeC 6H 4 (Id), 4′-MeOC 6H 4 (Ie), 4′-NO 2C 6H 4 (If) have been synthesized for the first time and were studied by NMR spectroscopy. In contrast to Ib in molecules of Ia (R = Me), IcIf the ClSi bond rather than OSi bond is the weaker component of the hypervalent OSiCl bond, which implies the possibility of Cl → Si coordinative interaction. An irreversible rearrangement of compounds I upon heating leads to (OSi)chloro[2-(1,1-dimethyl-2-acylhydrazino)methyl]dimethylsilanes, Me 2Cl SiCH 2-N[C(O) R]NMe 2 (II), and was used for preparative purposes.