The infra-red spectrum, structure, and normal vibrations of the guanidinium ion

Abstract

The infra-red spectrum of guanidinium chloride and iodide and their perdeutero derivatives have been obtained in the region 3600 to 400 cm-1. From the present infrared data and previously determined Raman data an assignment has been made for the spectroscopically active fundamental vibration frequencies of the guanidinium ion which is in good agreement with the requirements of the product rule. The infra-red results for the particularly symmetrical iodide crystals are consistent with a D3h all-planar structure for the ion slightly distorted by crystal forces corresponding to the site symmetryThe normal vibrations of the C(NHZ)~+ and C(ND2)3+ ions have been calculated as a ten-body problem on the basis of a Urey-Bradley type of force field. A reasonable set of force constants is obtained so as to give the best fit with the observed frequencies. The distribution of the potential energy among symmetry co-ordinates has been calculated and the contributions of the latter to each normal vibration has been discussed.Close analogies between the spectra of urea (which is known to be an all-planar molecule) and of the guanidinium ion and the amides, R . CONH2, support the assumption of planar structures for the latter two species.

The Dielectric and Dilatometric Single Crystal Studies of Phase Transitions in a New Member of Family of Halogenoantimonates(III) [C(NH2)3l2SbCl5· [C(NH2)3]Cl

“…The transition near 146 K is accompanied by a distinct spontaneous change in lengths (AL/L) of about -1.6 • 10~4, + 1.1 10' 4 and +2. 4 • 10~4 along the a-, b-, and c-axes, respectively.…”

“…The molecular dynamics of guanidinium salts has been studied by IR [1][2][3][4], NMR [5][6][7][8][9][10] and NQR [5] spectroscopy, and the structure of many simple guani dinium salts is known, e.g. [11][12][13].…”

Vibrational Spectroscopic Properties of a [C(NH2)3]4Cl2SO4Ferroelectric Crystal - An Experimental and Theoretical Study

“…Crystals containing guanidinium cations and dierent inorganic salts or acids as anions have been extensively studied for years [1]. The guanidine is a small molecule and can be used as a component in supramolecular chemistry.…”

The infrared spectra of primary aromatic amides

“…The data listed in Table 11 show that all the aromatic amides included in the present investigation have a band in the region of the spectrum between 620 and 680 cm" 1 that is sensitive to 1^N substitution and disappears upon deuteration, apparently shifting to near 500 cm" 1 The only NH2 vibration remaining to be assigned is the asymmetric out-of-plane deformation. Since this vibration in volves very little nitrogen motion, the use of substitution will be of no value in its identification.…”

“…Because this is in the expected frequency range for an NHg rocking vibration (1,12,17,24,29,37,40), the amide IV band has been associated with such a vibration. Weckerlin and Luttke (41) found the amide IV band in benzamide to be sensitive to substitution lending further support to the assignment.…”