2-(Ammoniummethyl) pyridinium dihydrogen squarate hydrate: An experimental and theoretical study

Crystal structure of 2-ethyl-4-methyl-1-(2-oxido-3,4-dioxocyclobut-1-en-1-yl)-1H-imidazol-3-ium

“…Single-bond character is observed for C1-C2 and C2-C3 [1.514 (5) and 1.516 (5) Å , respectively]. The observed bond lengths indicate a degree of delocalization in the squarate ring, as has been observed in previous studies (Kolev et al, 2005;Korkmaz et al, 2013). The C1-O1 and C3-O3 bond lengths are 1.234 (4) and 1.216 (4) Å , respectively.…”

“…The NÁ Á ÁO distance should be in the region of 2.72-2.78 Å , The observed N1-H1Á Á ÁO1 i DÁ Á ÁA distance [2.680 (3) Å ; Table 1] corresponds to a [(+/À)CAHB] interaction. Looking at the NÁ Á ÁO distances in the symmetry-related hydrogen bonding between squarate ring systems, it can be seen that the interaction is slightly shorter than the relevant interval values and is symbolized as either N + -HÁ Á Á O 1\2À or N + -HÁ Á Á O À (+/À)CAHB (Korkmaz & Bulut, 2013). The C-HÁ Á ÁO (Table 1, Fig.…”

NH⋯O and OH⋯O interactions of glycine derivatives with squaric acid

“…In the crystal of 3 the dimers are linked to form two cyclamers described by the graph set R 6 6 (30), 24 where the N-H atoms engaged in the N(1)-H(1)Á Á ÁO(1 0 ) and N(1 0 )-H(1 0 )Á Á ÁO(2) hydrogen bonds of 2.870(2) and 2.803(2) Å, respectively (Fig. 7, Table 2), play the main role.…”

Crystal structure of 2-(azaniumylmethyl)pyridinium bis(hydrogen squarate)

“…The squarate derivatives are almost flat because of the -conjugation of their C-C and C-O bonds, and therefore their four oxygen atoms behave as planar (sp 2 ) electron donors of one or two lone pairs of electrons. Recently, we reported the synthesis and characterization of the same organoammonium squarate as the title compound but as a hydrate in the triclinic space group P1 (Korkmaz & Bulut, 2013). We report here the unsolvated form of this salt, which crystallizes in the monoclinic space group P2 1 /c.…”

“…In the squarate anion form, the anions are generally linked to amines by N-HÁ Á ÁO hydrogen bonds (Gilli et al, 2001;Korkmaz et al, 2011;Dega-Szafran et al, 2012). Structures of 2-(amoniomethyl) pyridinium, dihydrogen squarate and squaric acid derivatives are also known (Korkmaz et al, 2011;Korkmaz & Bulut, 2013, 2014. Often, the supramolecular architectures of similar structures have been investigated together with their spectroscopic properties, including their potential non-linear optical (NLO) behaviour (Bosshard et al, 1995;Kolev et al, 2008 Hydrogen-bond geometry (Å , ).…”