Solvent‐mediated pseudo‐quadruple hydrogen‐bond motifs in three lamotrigine–carboxylic acid complexes
Lamotrigine, an antiepileptic drug, has been complexed with three aromatic carboxylic acids. All three compounds crystallize with the inclusion of N,N‐dimethylformamide (DMF) solvent, viz. lamotriginium [3,5‐diamino‐6‐(2,3‐dichlorophenyl)‐1,2,4‐triazin‐2‐ium] 4‐iodobenzoate N,N‐dimethylformamide monosolvate, C9H8Cl2N5 +·C7H4IO2 −·C3H7NO, (I), lamotriginium 4‐methylbenzoate N,N‐dimethylformamide monosolvate, C9H7Cl2N5 +·C8H8O2 −·C3H7NO, (II), and lamotriginium 3,5‐dinitro‐2‐hydroxybenzoate N,N‐dimethylformamide monosolvate, C9H8Cl2N5 +·C7H3N2O7 −·C3H7NO, (III). In all three structures, proton transfer takes place from the acid to the lamotrigine molecule. However, in (I) and (II), the acidic H atom is disordered over two sites and there is only partial transfer of the H atom from O to N. In (III), the corresponding H atom is ordered and complete proton transfer has occurred. Lamotrigine–lamotrigine, lamotrigine–acid and lamotrigine–solvent interactions are observed in all three structures and they thereby exhibit isostructurality. The DMF solvent extends the lamotrigine–lamotrigine dimers into a pseudo‐quadruple hydrogen‐bonding motif.
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Document Type: Research Article
Affiliations: X-ray Crystallography Division, CSIR – Indian Institute of Chemical Technology, Hyderabad 500 007, India
Publication date: October 15, 2013