Jump to main content
Jump to site search

Issue 15, 1998
Previous Article Next Article

O-Oximatosilanes: weak β-donor interactions as secondary bonds

Abstract

The oximatosilanes H3SiON[double bond, length half m-dash]CMe2, ClH2SiON[double bond, length half m-dash]CMe2 and H2Si(ON[double bond, length half m-dash]CMe2)2 were prepared from the reaction of lithiated acetone oxime with bromosilane and dichlorosilane respectively. They have been characterised by NMR (1H, 13C, 15N, 17O and 29Si) and by gas-phase IR spectroscopy. The molecular structures of H3SiON[double bond, length half m-dash]CMe2 and H2Si(ON[double bond, length half m-dash]CMe2)2 have been determined by low-temperature X-ray crystallography. Small Si–O–N angles have been detected in these structures, which are indicative of the formation of weak secondary interactions of the β-donor–acceptor type between silicon and nitrogen atoms. Important geometrical parameters: H3SiON[double bond, length half m-dash]CMe2, Si–O 1.673(1), N–O 1.433(1) Å, Si–O–N 106.0(1)°, N[double bond, length half m-dash]C 1.273(2) Å; H2Si(ON[double bond, length half m-dash]CMe2)2, Si–O 1.657(1), 1.650(1), N–O 1.466(2), 1.447(2), N[double bond, length half m-dash]C 1.271(2), 1.266(2) Å, Si–O–N 102.5(1), 107.5(1)°. The geometries of H3SiON[double bond, length half m-dash]CMe2, FH2SiON[double bond, length half m-dash]CMe2 and ClH2SiON[double bond, length half m-dash]CMe2 were calculated by optimisations at the MP2/6-311G** level of theory. The Si–O–N angles in FH2SiON[double bond, length half m-dash]CMe2 and ClH2SiON[double bond, length half m-dash]CMe2 are predicted to be smaller than that in H3SiON[double bond, length half m-dash]CMe2. A natural bond orbital analysis describes the β-donor interaction as weak negative hyperconjugation lp(O)→σ*(SiO) and lp(O)→σ*(SiH). In general the β-donor bonds in oximatosilanes are found to be weaker than in the related hydroxyaminosilanes.

Back to tab navigation

Supplementary files


Article type: Paper
DOI: 10.1039/A802914H
J. Chem. Soc., Dalton Trans., 1998, 2537-2540

  •   Request permissions

    O-Oximatosilanes: weak β-donor interactions as secondary bonds

    U. Losehand and N. W. Mitzel, J. Chem. Soc., Dalton Trans., 1998, 2537
    DOI: 10.1039/A802914H

Search articles by author

Spotlight

Advertisements