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The Complex of N-methylmorpholine Betaine with 3,4-dinitrophenol Studied by FTIR, UV, NMR Spectroscopies, X-ray Diffraction and DFT Calculations

Zofia Dega-Szafran ¹, Andrzej Katrusiak , Mirosław Szafran

1. Adam Mickiewicz University, Faculty of Chemistry, Grunwaldzka 6, Poznań 60-780, Poland

Abstract

N-methylmorpholine betaine forms a crystalline 1:1 complex with 3,4-dinitrophenol. Its structure was solved by X-ray diffraction; the crystal is monoclinic in space group P2₁/c. The morpholinium ring has a chair conformation with the CH₂COO^- substituent in the axial and the methyl group in the equatorial positions. The hydroxyl group of phenol and the carboxylate group of betaine are engaged in the O-H···O hydrogen bond of 2.471 Å.

The FTIR spectrum shows an intense broad absorption in the 1500-800 cm^-1 region, characteristic for the short hydrogen bond.
The UV absorptions depend on the polarity of solvents used (DMSO, CH₃CN). Two bands at ca. 310 and 425 nm suggest an equilibrium between the molecular complex and the hydrogen-bonded ion-pair in solution.
The optimized geometry of the complex investigated by the B3LYP/6-31G(d,p) approach is in a good agreement with the crystal structure. Linear correlations have been found between the experimental ¹H and ¹³C chemical shifts and the magnetic isotropic shielding tensors computed by the GIAO/B3LYP/6-31G(d,p) method, which confirm the correct assignments of the proton and carbon chemical sfifts.

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The Complex of N-methylmorpholine Betaine with 3,4-dinitrophenol Studied by FTIR, UV, NMR Spectroscopies, X-ray Diffraction and DFT Calculations

Presentation: oral at 18th Conference on Physical Organic Chemistry, Symposium 2, by Zofia Dega-Szafran See On-line Journal of 18th Conference on Physical Organic Chemistry Submitted: 2006-05-05 11:12 Revised: 2009-06-07 00:44

Presentation: oral at 18th Conference on Physical Organic Chemistry, Symposium 2, by Zofia Dega-Szafran
See On-line Journal of 18th Conference on Physical Organic Chemistry

Submitted: 2006-05-05 11:12 Revised: 2009-06-07 00:44