Structural Investigations into the β-Effect of Pentavalent Silicon

Ester and ether derivatives of 2-[(8-dimethylaminonaphthalen-1-yl)dimethylsilanyl]ethanol (10a) were prepared as part of a preliminary study to determine the β-effect of pentavalent silicon. The p-nitrobenzoate, 3,5-dinitrobenzoate, and o-nitrobenzoates ester derivatives 10e−10g, which were characterized using X-ray crystallography, showed partial distortion of the silicon toward a trigonal bipyramidal geometry with the peri-nitrogen occupying one of the apical sites. The second apical site is occupied by a CH3 substituent in 10e and 10f, while the CH2CH2OR substituent occupies the apical position in 10g. The C−OR bond distances in these structures were lengthened compared to standard values, consistent with the presence of a strong σ−σ∗ interaction between the σC-Si bonding orbital and the σ∗C-OR antibonding orbital.