The O-H•••O, O-H•••N and C-H•••O hydrogen bonds in 1,4-dimethylpiperazine mono-betaine monohydrate

1,4-Dimethylpiperazine mono-betaine (1-carboxymethyl-1,4-dimethylpiperazinium inner salt, MBPZ) crystallizes as monohydrate. The crystals are orthorhombic, space group Pccn. Two MBPZ molecules and two water molecules form a cyclic oligomer, (MBPZ center dot H2O)(2). The O-H center dot center dot center dot O and O-H center dot center dot center dot N hydrogen bonds are of 2.769(1) and 2.902(1) angstrom, respectively. The dimers interact with the neighboring molecules through the C-H center dot center dot center dot O hydrogen bonds of 3.234(1) A. The piperazine ring assumes a chair conformation with the N(4)-CH3 and N+(1)-CH2COO- groups in the equatorial position and the N+(1)-CH3 group in the axial one. The FTIR spectrum is compared with that calculated by the B3LYP/6-31G(d,p) level of theory. (c) 2007 Elsevier B.V. All rights reserved.