The Molecular and Crystal Structure of 3,5-Dimethylpyrazole with Chloranilic Acid Adduct

Abstract

45 X-rayStructureAnalysisOnline2014,VOL.30 45 2014©TheJapanSocietyforAnalyticalChemistry Pyrazoles are promising model compounds and convenient componentsforbuildingupsupramolecularsystems.Duetothe presenceofan=N-N(H)fragment,pyrazolederivativespossess a unique ability to form various self-associates in the gaseous phase, in crystal, and in solution. 1 Studies of such kind have useful applications in pharmacology, typically as non-narcotic analgesics, as well as the field of drug-receptor binding mechanisms in medicinal chemistry. 2 Thus, the complexes of pyrazole derivatives with proton donor and acceptors compoundsarebeingstudiedbymanysupramolecularchemists.Recently, we obtained an adduct of 3,5-dimethylpyrazole (3,5DMP,anorallyactivehypoglycemicagent,andeffectiveon carbohydrate and free fatty acid metabolism) with chloranilic acid(CLA,aprotondonor).Wesubsequentlyinvestigatedthe effectofmethylsubstituentsonthepackingmodeintheadduct, since;eitherofthemethylgroupsmayhaveapropensitytobe out-of-planeofthepyrazolering,andthusinfluencethepacking fashion and hydrogen-bond patterns. We also considered how the presence of competitive hydrogen bond donor-acceptor groupscanenhanceapossibleprotontransferprocess.Thus,in this manuscript the aforementioned aims are discussed. The crystal complex was obtained by dissolving a 1:1 mixture of 3,5DMP(0.20g,2mmol)andCLA(0.42g,2mmol)in20ml of methanol and allowed to evaporate slowly at room temperature. Suitable crystals were obtained after eight days, and characterized through X-ray diffraction at 150 K. Crystal data and details of data collection are given in Table 1. The structuresolutionwascarriedoutwithdirectmethodsusingthe programs SIR 92 or superflip within the CRYSTALS software suite,andrefinedbyfull-matrixleast-squaresmethodsbasedon F 2 . The chemical structure of the adduct is shown in Fig. 1, whiletheatomnumberingfollowstheschemeindicatedinFig. 2. The bond lengths and angles in CLA are insignificantly different from those in the crystal structure of CLA. 3 The geometry of the 3,5DMP ring shows a similar pattern of bond distances and angles as pyrazole, 4 and shows an insignificant effect of the hydrogen-bonding interaction on the bonded X-ray Structure Analysis Online

Crystal Structure of Anhydrous 1:1 Non-Proton Charge-Transfer Adduct of Zwitterionic Quinaldic Acid with Chloranilic Acid

“…A dimeric unit is formed via N + -H···Ocarboxyl interactions, and interlinked with O-H···Ocarboxyl, and water O-H···O without π···π interactions between the zQA molecules, but shows C-H···O associations. Recently, we reported on a hydrated 1:1 non-proton-transfer adduct of zQA with chloranilic acid (CLA), 5 and attributed the π···π interactions between the zQA molecules to H-bond effects of the water of solvation. So far, the π···π interactions between the QA molecules in hydrous and anhydrous proton/non-proton transfer QA adducts are not clearly understood, so we found it prudent to investigate the crystal structure of anhydrous 1:1 QA/CLA, and to compare with 1:1 QA/CLA, 5 in order to understand the interactions between the QA or CLA molecules, and QA/CLA for the purpose of employing this knowledge in crystal engineering studies.…”

“…The bond lengths and angles in CLA, and QA are within those in CLA, 6 QA, 7 and in 1:1 QA/CLA. 5 The carboxylate ion group rotates slightly out of the plane of the quinolium cation with a 2016 © The Japan Society for Analytical Chemistry † To whom correspondence should be addressed. E-mail: emmanuel_jp@yahoo.com torsional angle of N11-C10-C18-O7 (-5.76(19) ); it is different from that in hydrous 1:1 QA/CLA (N2-C13-C20-O7 (-18.1(2) )).…”

“…The N11-H111···O7 (N11···O7; 2.760(2), H111···O7; 1.91 Å interaction is essential for linking two adjacent zQA molecules that form a dimer around a center of inversion, as in 1:1 QA/CLA. 5 The OH groups in CLA facilitate parallel packing of the dimeric zQA molecules via O6-H61···O9 (O6···O9; 2.502(2)Å, H61···O9; 1.69 Å), and C3-O6···H191 (O6···H191; 2.62 Å interactions (Fig. 3), and maintain the planar conformation of the dimeric zQA molecules, as in the hydrous crystal in which the OH groups in water, and in CLA play significant roles in the formation of the planar conformation of the dimeric zQA molecules via O-H···O, and effects π···π interactions between the zQA molecules.…”

Elucidation of the Alternating Copolymerization Mechanism of Epoxides or Aziridines with Cyclic Anhydrides in the Presence of Halide Salts

“…Crystals of TPEAC ⋅ Cl and TBAC ⋅ Cl were obtained by evaporation of methanol at room temperature in the glove box. The crystal structures of PPN ⋅ Cl [26] and TBA ⋅ Cl [27] were added as references. TPEAC ⋅ Cl and TBAC ⋅ Cl crystallize in orthorhombic space group Pbca and monoclinic space group C 12/ c 1, respectively.…”