Two concomitant polymorphs of the molecular salt formed by 2,6-dimethoxybenzoic acid, C9H10O4 (Dmb), with benzamidine, C7H8N2 (benzenecarboximidamide, Benzam) from water solution have been identified. Benzamidinidium 2,6-dimethoxybenzoate, C7H9N2+center dot C9H9O4- (BenzamH(+)center dot Dmb(-)), was obtained through protonation at the imino N atom of Benzam as a result of proton transfer from the acidic hydroxy group of Dmb. In the monoclinic polymorph, (I) (space group P2(1)/n), the asymmetric unit consists of two Dmb(-) anions and two monoprotonated BenzamH(+) cations. In the orthorhombic polymorph, (II) (space group P2(1)2(1)2(1)), one Dmb(-) anion and one BenzamH(+) cation constitute the asymmetric unit. In both polymorphic salts, the amidinium fragments and carboxylate groups are completely delocalized. This delocalization favours the aggregation of the molecular components of these acid-base complexes into nonplanar dimers with an R-2(2)(8) graph-set motif via N+-H center dot center dot center dot O- charge-assisted hydrogen bonding. Both the monoclinic and orthorhombic forms exhibit one-dimensional isostructurality, as the crystal structures feature identical hydrogen-bonding motifs consisting of dimers and catemers.
Supramolecular association in proton-transfer adducts containing benzamidinium cations. II. Concomitant polymorphs of the molecular salt of 2,6-dimethoxybenzoic acid with benzamidine / Irrera, Simona; Ortaggi, Giancarlo; Portalone, Gustavo. - In: ACTA CRYSTALLOGRAPHICA. SECTION C, CRYSTAL STRUCTURE COMMUNICATIONS. - ISSN 0108-2701. - STAMPA. - 68:Pt 11(2012), pp. O447-+. [10.1107/s010827011204067x]
Supramolecular association in proton-transfer adducts containing benzamidinium cations. II. Concomitant polymorphs of the molecular salt of 2,6-dimethoxybenzoic acid with benzamidine
IRRERA, SIMONA;ORTAGGI, Giancarlo;PORTALONE, Gustavo
2012
Abstract
Two concomitant polymorphs of the molecular salt formed by 2,6-dimethoxybenzoic acid, C9H10O4 (Dmb), with benzamidine, C7H8N2 (benzenecarboximidamide, Benzam) from water solution have been identified. Benzamidinidium 2,6-dimethoxybenzoate, C7H9N2+center dot C9H9O4- (BenzamH(+)center dot Dmb(-)), was obtained through protonation at the imino N atom of Benzam as a result of proton transfer from the acidic hydroxy group of Dmb. In the monoclinic polymorph, (I) (space group P2(1)/n), the asymmetric unit consists of two Dmb(-) anions and two monoprotonated BenzamH(+) cations. In the orthorhombic polymorph, (II) (space group P2(1)2(1)2(1)), one Dmb(-) anion and one BenzamH(+) cation constitute the asymmetric unit. In both polymorphic salts, the amidinium fragments and carboxylate groups are completely delocalized. This delocalization favours the aggregation of the molecular components of these acid-base complexes into nonplanar dimers with an R-2(2)(8) graph-set motif via N+-H center dot center dot center dot O- charge-assisted hydrogen bonding. Both the monoclinic and orthorhombic forms exhibit one-dimensional isostructurality, as the crystal structures feature identical hydrogen-bonding motifs consisting of dimers and catemers.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.