Correlation between proton transfer and ³⁵Cl NQR frequency as well as molecular geometry of chloranilic acid in co‐crystals with some organic bases

Abstract

Proton transfer in hydrogen-bonded organic co-crystals of chloranilic acid with some organic bases was investigated by nuclear quadrupole resonance (NQR) spectroscopy. The (35)Cl NQR frequencies of chloranilic acid molecule as well as (14)N NQR frequencies of the organic base molecule were measured with the conventional pulse methods as well as double-resonance methods, respectively. The extent of proton transfer in the O...H...N hydrogen bond was estimated from Townes-Dailey analysis of the (14)N NQR parameters. The (35)Cl NQR frequency and molecular geometry of chloranilic acid are correlated to the extent of proton transfer in the protonation process of the organic base molecule. It is shown that the hydrogen bond affects the pi-electron system of chloranilic acid. Geometry dependence of the O...H...N hydrogen bond, i.e. the H-N valence bond order versus the hydrogen-bond geometry correlation is also discussed.

Temperature dependence of one-dimensional hydrogen bonding in morpholinium hydrogen chloranilate studied by 35Cl nuclear quadrupole resonance and multi-temperature X-ray diffraction

“…114.0492 (7) 114.0287 (7) 113.9804 (7) 113.9058 (7) 113.8619 (7) 113.8289 (7) 113.7992 (7) Volume (A ˚3) the energy difference DH between O2-H2Á Á ÁO4 and O2Á Á ÁH4-O4 states and the entropy term a were determined to be 0.600 (9) kJ mol À1 [72(1) K] and À0.11 (7), respectively, by fitting the equation to ln K vs. T À1 plots in Fig. 5.…”

“…This technique has been successfully applied to investigate the dynamic disorder of the H-atom involved in the OÁ Á ÁHÁ Á ÁN hydrogen bond of the 2 : 1 compounds of diazine and chloranilic acid systems, [2][3][4][5][6] or to evaluate proton transfer between chloranilic acid and an organic base in some organic co-crystals. 7 For the 1 : 1 compounds of chloranilic acid and organic base systems, hydrogen-bonded B:C:C:B discrete units, -C:C:(B2):C:C:(B2)-, or -C:B:C:B-chains (C: chloranilic acid, B: organic base) have been frequently observed in the crystals. [8][9][10] Among such 1 : 1 crystals, there exists an interesting compound, namely, morpholinium hydrogen chloranilate, in which one proton is transferred from a chloranilic acid molecule to a morpholine molecule as expected from the pK a value of morpholine (8.36) 10 and the acid molecules are arranged one-dimensionally by disordered O-HÁ Á ÁO hydrogen bonds.…”

Crystal structures of two hydrogen-bonded compounds of chloranilic acid–ethyleneurea (1/1) and chloranilic acid–hydantoin (1/2)

“…Chloranilic acid, a dibasic acid with hydrogen-bond donor as well as acceptor groups, appears particularly attractive as a template for generating tightly bound self-assemblies with various organic bases, and also as a model compound for investigating hydrogen-transfer motions in O-HÁ Á ÁN and N-HÁ Á ÁO hydrogen-bonded systems (Zaman et al, 2004;Seliger et al, 2009;Asaji et al 2010;Molčanov & Kojić-Prodić, 2010). In the present study, we have prepared two hydrogenbonded compounds of chloranilic acid-ethyleneurea (1/1) and chloranilic acid-hydantoin (1/2) in order to extend our study on D-HÁ Á ÁA hydrogen bonding (D = N, O, or C; A = N, O or Cl) in chloranilic acid-organic base systems (Gotoh & Ishida, 2017a,b, and references therein).…”

Crystal structures of three hydrogen-bonded 1:2 compounds of chloranilic acid with 2-pyridone, 3-hydroxypyridine and 4-hyroxypyridine

“…Chloranilic acid, a dibasic acid with hydrogen-bond donor and acceptor groups, appears particularly attractive as a template for generating tightly bound self-assemblies with various pyridine derivatives, as well as a model compound for investigating hydrogen transfer motions in O-HÁ Á ÁN and N-HÁ Á ÁO hydrogen-bond systems (Zaman et al, 2004;Seliger et al, 2009;Asaji et al 2010). In the present study, we have prepared three 1:2 compounds of chloranilic acid with 2-pyridone, 3-hydroxypyridine and 4-hydroxypyridine in order to extend our study of D-HÁ Á ÁA hydrogen bonding (D = N, O or C; A = N, O or Cl) in chloranilic acid-substitutedpyridine systems (Gotoh et al, 2009a(Gotoh et al, ,b, 2010.…”