Crystal structure and Raman spectra of rubidium hydrogen squarate

Crystal structure and spectroscopic properties of ammonium hydrogensquarate squaric acid monohydrate

“…The participation of the OH groups of H 2 Sq and HSq @ species in strong (2.495 and 2.587 Å ) intermolecular interactions causes a low frequency shifting of these IR-bands to 2,450 cm @1 . These data correct well with previously reported values for squaric acid derivatives, with the obtained differences being fewer than 10 cm @1 [10,11]. The observed broad absorption maximum within the whole 3,500-2,400 cm @1 IR-region is assigned to asymmetric and symmetric stretching (m as NH4+ , m s NH4+ ) vibrations of the NH 4 + anions.…”

“…The optimized geometry parameters (Scheme 2) show that the bond lengths and angles in the interacted moieties are similar and differ less than 0.0300 Å and 0.02 o . The obtained geometry parameters are in accordance with those of isolated H 2 Sq and HSq @ [10,11]. Can we describe the interacting H 2 Sq/HSq @ system as consisting of separately molecules H 2 Sq an HSq @ , joined by intermolecular interactions or to a first approximation do we have the characteristics of a hydrogen bonding influenced H 2 Sq and HSq @ system?…”

“…According to our theoretical data the second proposition is more realistic in gas phase. For the reason namely that the calculated IR-spectrum if the system is close to that of the pure squaric acid [11][12][13][14]. Comparing both sets of theoretical data, the obtained differences between m C = O , m as C=O , m C=C and of m OH about : 9 cm @1 can be attributed to the influence of the interaction on the geometry of the species.…”

“…3.1) is characterized by an underlying complicated IR-spectroscopic pattern like other squaric acid derivatives [7][8][9][10][11][12][13][14]. However in this case the presence of the ammonium cation and H 2 O molecules, both possessing series of stretching and bending characteristic IR-bands, leads to strong overlapping of the bands especially in the 3,500-2,800 cm @1 region.…”

“…As established in series of systematic crystallographic studies on the self-assembly of squarates and hydrogensquarates [1][2][3][4][5][6]. Detailed studied on the correlation of vibrational spectroscopic properties and structural motifs in squaric acid derivatives have been reported [7][8][9][10][11][12][13][14].…”