Hydrogen-bonded molecular salts of reduced benzothiazole derivatives with carboxylates : a robust R_{2}^{2}(8) supramolecular motif (even when disordered)
Abstract
The syntheses and structures of five molecular salts of protonated 4,4,7,7-tetramethyl-3a,5,6,7a-tetrahydrobenzothiazol-2-ylamine (C11H 19N 2S +) with different deprotonated carboxylic acids (4-methylbenzoic acid, 4-bromobenzoic acid, 3,5-dinitrobenzoic acid, fumaric acid and succinic acid) are reported, namely 2-amino-4,4,7,7-tetramethyl-4,5,6,7-tetrahydro-1,3-benzothiazol-3-ium 4-methylbenzoate, C11H 19N 2S +·C 8H 7O 2 −, (I), 2-amino-4,4,7,7-tetramethyl-4,5,6,7-tetrahydro-1,3-benzothiazol-3-ium 4-bromobenzoate, C11H 19N 2S +·C 7H 4BrO 2 −, (II), 2-amino-4,4,7,7-tetramethyl-4,5,6,7-tetrahydro-1,3-benzothiazol-3-ium 3,5-dinitrobenzoate, C11H 19N 2S +·C 7H 3N 2O 6 −, (III), bis(2-amino-4,4,7,7-tetramethyl-4,5,6,7-tetrahydro-1,3-benzothiazol-3-ium) fumarate, 2C11H 19N 2S +·C 4H 2O 4 2−,(IV), and the 1:1 co-crystal of bis(2-amino-4,4,7,7-tetramethyl-4,5,6,7-tetrahydro-1,3-benzothiazol-3-ium) succinate and 2-amino-4,4,7,7-tetramethyl-4,5,6,7-tetrahydro-1,3-benzothiazol-3-ium hydrogen succinate 4,4,7,7-tetramethyl-3a,5,6,7a-tetrahydrobenzothiazol-2-ylamine, 1.5C11H 19N 2S +·0.5C 4H 4O 4 2−·0.5C 4H 5O 4 −. 0.5C11H 18N 2S, (V). In every case, the cation protonation occurs at the N atom of the thiazole ring and the six-membered ring adopts a half-chair conformation (in some cases, the deviating methylene groups are disordered over two sets of sites). The C—N bond lengths of the nominal –NH+=C—NH 2 fragment of the cation are indistinguishable, indicating a significant contribution of the –NH—C=N+H 2 resonance form to the structure. The packing for (I)–(V) features a robust local R 2 2(8) loop motif in which the cation forms two near-linear N—H⋯O hydrogen bonds from the N+—H group and syn H atom of the amine group to the carboxylate group of an adjacent anion [(V) shows disorder of one of these bonds over N—H⋯O and N⋯H—O contributors but the same R 2 2(8) loop results for both disorder components]. The anti H atom of the –NH2 group also forms an N—H⋯O hydrogen bond, which results in [001] chains in (I) and (II), isolated centrosymmetric tetramers in (III) and [100] chains in (IV) and (V). Hirshfeld fingerprint plots and contact percentages for the different types of contacts of the cations are discussed.
Citation
Shaibah , M A E , Sagar , B K , Yathirajan , H S , Cordes , D B , Slawin , A M Z & Harrison , W T A 2019 , ' Hydrogen-bonded molecular salts of reduced benzothiazole derivatives with carboxylates : a robust R_{2}^{2}(8) supramolecular motif (even when disordered) ' , Acta Crystallographica Section E , vol. 75 , no. 2 , pp. 167-174 . https://doi.org/10.1107/S2056989018018224
Publication
Acta Crystallographica Section E
Status
Peer reviewed
ISSN
2056-9890Type
Journal article
Rights
Copyright © 2019 The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Description
HSY thanks UGC for the award of a UGC–BSR Faculty Fellowship for three years. BKS thanks the UGC for the award of a Rajeev Gandhi fellowship.Collections
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