(O-Si)-Chelate acetic and benzoic acid N-(fluorosilylmethyl)amides: synthesis and structure

New representatives of (O-Si)-chelate compounds, N-(fluorosilyl)methyl derivatives of N-methylacetamide, N-methylbenzamide, N-phenylacetamide, and N-phenylbenzamide, were synthesized using different synthetic approaches. An analysis of the structures of these compounds established by 29Si NMR spectroscopy and X-ray diffraction and the published data showed that the degree of C-O→Si dative interaction decreases when the methyl group on the nitrogen atom is replaced by a phenyl substituent. The replacement of the methyl substituent at the carbonyl group by a phenyl substituent has a less significant effect but also leads to a decrease in the C-O→Si dative bonding. The X-ray diffraction study of N-[(difluoromethylsilyl)methyl]-N-phenylbenzamide at 100 and 293 K provided evidence that the C-O→Si dative bond length changes inversely to changes in the equatorial bond lengths of the C-O→SiC2F2 coordination unit with a change in the temperature.