STRUCTURAL ANALYSIS AND DIPOLE MOMENT DETERMINATION OF THE GAS-PHASE TRIMETHY-LAMINE SULFUR TRIOXIDE COMPLEX
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Date
1999
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Publisher
Ohio State University
Abstract
The structure and dipole moment of the Lewis acid-base adduct $(CH_{3})_{3} N-SO_{3}$ have been determined by microwave spectroscopy. Analysis yields an N-S bond length of $1.914(33) {\AA}$ and an NSO angle of $100.0(4)^{\circ}$. These data indicate that the formation of the N-S dative bond is nearly (but not entirely) complete in the gas phase. Comparison with previous work on the closely related system $H_{3}N-SO_{3}$ indicates that the increased basicity of the $(CH_{3})_{3}N$ relative to that of $H_{3}N$ is effective at driving the dative bond further towards completion. Analysis of nuclear hyperfine structure indicates that about 0.6 electrons are transferred from the nitrogen to the $SO_{3}$ upon formation of the complex. This is significantly larger than that observed in $H_{3}N-SO_{3}$. The dipole moment, obtained from Stark effect measurements, of 7.111(7)D, arises from a combination of charge transfer, out-of-plane distortion of the $SO_{3}$ and the intrinsic moment of $(CH_{3})_{3}N$.
Description
Author Institution: Department of Chemistry, University of Minnesota; Department of Chemistry, Pontifical Catholic University of Puerto Rico,