DFT study of structural and vibrational properties of guanidinium derivatives

We present a comparison of the vibrational spectra of guanidinium chloride in aqueous solution and in the crystal phase from density functional calculations with experimental data from the literature. In addition, we investigated the structural and vibrational properties of two conformations of guanidinium formate in aqueous solution. For the purposes of comparison, these data were supplemented with crystal phase calculations of the structural parameters and vibrational spectra of guanidinium nitrate, carbonate and oxalate. For the conformations 1 and 2 of the guanidinium formate in aqueous solution, we found infrared frequencies at 558 and 525 cm(-1), corresponding to the CN3 bending, at 1112 and 1132 cm(-1), corresponding to the NH2 rock and twist motions, at 1671 and 1661 cm(-1), corresponding to the "scissors" motions of the C, N and H atoms, and at 3200-3500 cm(-1), corresponding to the NH2 motions. The C-O and C-H vibrations of the formic acid part were found at 1331 and at 1035 cm(-1), and at 1317 and at 1048 cm(-1), for conformation I and conformation 2. respectively. (C) 2009 Elsevier B.V. All rights reserved.