Structural, spectroscopic and theoretical studies of the 1:1 complex of N-methylpiperidine betaine with squaric acid

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• 作者：Z. Dega-Szafran ; ^{degasz@amu.edu.pl} ; G. Dutkiewicz ; Z. Kosturkiewicz ; M. Szafran
• 关键词：N-methylpiperidine betaine ; Squaric acid ; Hydrogen bonds ; X-ray diffraction ; FTIR and NMR spectroscopies ; DFT calculations
• 刊名：Journal of Molecular Structure
• 出版年：2012
• 期刊代码：62_00222860
• 类别：ch
• 出版时间：16 May, 2012
• 卷：1015
• 期：Complete
• 页码：86-93
• 文件大小：598 K

摘要

The 1:1 complex of N-methylpiperidine betaine, MPB, with squaric acid, H₂SQ, has been characterized by single-crystal X-ray analysis, FTIR and NMR spectroscopies, and by DFT calculations. The crystals are orthorhombic, space group Pbca. Two non-equivalent OH路路路O hydrogen bonds of 2.472(1) and 2.508(2) 脜 link H₂SQ with MPB. The piperidinium ring has a chair conformation with the methyl group in the equatorial position and the CH₂COO^{鈭?/sup> substituent in the axial one. The geometry of the optimized structures of the MPB路H₂SQ complex at the B3LYP/6-31G(d,p) level of theory, in a vacuum and solvated by water, have been used to calculate harmonic IR frequencies and to predict the chemical shifts in H₂O.}