N,N′-Dimethylpiperazine mono-betaine complex with two molecules of 3-iodobenzoic acid and water studied by X-ray diffraction, DFT, FTIR and NMR methods

✍ Scribed by Z. Dega-Szafran; A. Katrusiak; M. Szafran

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 758 KB
• Volume: 875
• Category: Article
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2007.05.044

✦ Synopsis

N,N 0 -Dimethylpiperazine mono-betaine (N-carboxymethyl-N,N 0 -dimethylpiperazinium inner salt, MBPZ) forms a crystalline complex with two molecules of 3-iodobenzoic acid (3IBA). The complex crystallizes as a monohydrate, MBPZ(3IBA) 2 H 2 O. The complex has been characterized by X-ray diffraction and FTIR, Raman, 1 H and 13 C NMR spectroscopies. The crystals are monoclinic, space group P2 1 /c, with a = 6.7810( 17), b = 38.391(4), c = 10.0542(16) A ˚, b = 90.024(18)°. The piperazinium ring has a chair conformation with the N + CH 2 COO À substituent in the axial and both methyl groups in the equatorial positions. The 3IBA molecules interact with the carboxylate group of N + CH 2 COO À and N 0 atom through the O-HAEAEAEO and O-HAEAEAEN hydrogen bonds of the lengths 2.550 and 2.695 A ˚. The water molecules link MBPZ(3IBA) 2 complexes by the O-HAEAEAEOOCCH 2 N + hydrogen bonds of 2.850 and 2.793 A ˚into infinite chains. The MBPZ(3XBA) 2 H 2 O (X = I, Br, Cl), MBPZ(3IBA) 2 complexes and MBPZ have been analyzed by the B3LYP/MidiX level of theory. The conformers with the axial CH 2 COO À substituent have lower energies than these with the equatorial CH 2 COO À one. The bands at 3433, 2790, 2450, 1915 cm À1 assigned to the m(OH) vibration of the various hydrogen bonds, and two bands attributed to the m(C@O) (1680 cm À1 ) and m as (COO) (1660 cm À1 ) vibrations in the FTIR spectrum confirm the structure of the title complex. The 1 H-13 C HMBC spectrum has been analyzed in order to assign the carbon-13 chemical shifts.