Crystal structure and spectroscopic properties of N-methylmorpholine betaine phosphate

The crystal and molecular structure of N-methylmorpholine betaine phosphate was solved by X-ray diffraction and four O .H .O hydrogen bonds were found. Two hydrogen atoms of phosphoric acid link both oxygen atoms of the N-methylmorpholine betaine by one short (O . . .O = 2.466(3) Angstrom) and one longer (O . . .O = 2.557(3) Angstrom) hydrogen bonds. The third hydrogen atom of phosphoric acid occupies the special position in the inversion centers of the unit cell and links PO4 groups by two short and symmetrical hydrogen bonds (2.464(3) and 2.444(3) Angstrom) into infinite chains parallel to the x-axis. The FTIR spectrum of the complex shows a broad and intense absorption in the 3000-400 cm(-1) region. Two different isotope effects (nu OH/nu OD) suggest that the absorption of the longer hydrogen bond is located in the 3000-1600 cm(-1) region, but that attributed to the shorter hydrogen bonds is in the 1600-400 cm(-1) region. (C) 2000 Elsevier Science B.V. All rights reserved.