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Tris(oxalato)chromate(III) hybrid salts templated by pyridinium and mixed pyridinium-ammonium cations: synthesis, structures and magnetism

Tris(oxalato)chromate(III) hybrid salts templated by pyridinium and mixed pyridinium-ammonium cations: synthesis, structures and magnetism
Tris(oxalato)chromate(III) hybrid salts templated by pyridinium and mixed pyridinium-ammonium cations: synthesis, structures and magnetism

By modifying the stoichiometric ratio of starting materials, two tris(oxalato)chromate(III) salts, (C7H11N2)3[Cr(C2O4)3] (1) and (C5H8N3)2(NH4)[Cr(C2O4)3]·2H2O (2) {(C7H11N2)+ = 2-amino-4,6-dimethylpyridinium, (C5H8N3)+ = 2,6-diaminopyridinium}, were synthesized and characterized by elemental and thermal analyses, single-crystal X-ray diffraction, IR and UV − Vis spectroscopies, EPR and SQUID measurements. Salt 1 exhibits a 3-D supramolecular framework based on [Cr(C2O4)3]3- and 2-amino-4,6-dimethylpyridinim cations, (C7H11N2)+, via N–H···O hydrogen bonds. Interestingly, π–π stacking interactions between pyridine rings contribute to the stabilization of the crystal packing. In contrast to salt 1, no π–π stacking interactions are observed in the mixed-cation salt 2 and its crystal packing is consolidated by N–H···O and O − H···O hydrogen bonds. EPR spectra of 1 and 2 are consistent with the oxidation state +3 of the chromium center in an octahedral environment. Temperature-dependence of the magnetic susceptibility data investigated from 2 to 300 K revealed the existence of zero-field splitting effects (ZFS) for Cr(III) ions in both compounds.

crystal structures, Hybrid salts, magnetism, oxalate chromium(III) complex, stoichiometry
0095-8972
1209-1221
Choubeu, Coustel M.N.
91101021-654a-4a3f-a44d-cc716f4e8301
Ndosiri, Bridget N.
bfd25af4-5d93-40b2-9ad1-7a351da5d3d4
Vezin, Hervé
82fdc1eb-a268-426e-97c2-6f115ea85ddf
Minaud, Claire
a876f260-3a75-47a7-9556-cd3ca93b86ed
Orton, James B.
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Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Nenwa, Justin
42cd6951-f090-4f24-9736-eb9351a94b67
Choubeu, Coustel M.N.
91101021-654a-4a3f-a44d-cc716f4e8301
Ndosiri, Bridget N.
bfd25af4-5d93-40b2-9ad1-7a351da5d3d4
Vezin, Hervé
82fdc1eb-a268-426e-97c2-6f115ea85ddf
Minaud, Claire
a876f260-3a75-47a7-9556-cd3ca93b86ed
Orton, James B.
4e2a471f-9e11-4cb4-abb6-d0398047939f
Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Nenwa, Justin
42cd6951-f090-4f24-9736-eb9351a94b67

Choubeu, Coustel M.N., Ndosiri, Bridget N., Vezin, Hervé, Minaud, Claire, Orton, James B., Coles, Simon J. and Nenwa, Justin (2021) Tris(oxalato)chromate(III) hybrid salts templated by pyridinium and mixed pyridinium-ammonium cations: synthesis, structures and magnetism. Journal of Coordination Chemistry, 74 (8), 1209-1221. (doi:10.1080/00958972.2021.1890048).

Record type: Article

Abstract

By modifying the stoichiometric ratio of starting materials, two tris(oxalato)chromate(III) salts, (C7H11N2)3[Cr(C2O4)3] (1) and (C5H8N3)2(NH4)[Cr(C2O4)3]·2H2O (2) {(C7H11N2)+ = 2-amino-4,6-dimethylpyridinium, (C5H8N3)+ = 2,6-diaminopyridinium}, were synthesized and characterized by elemental and thermal analyses, single-crystal X-ray diffraction, IR and UV − Vis spectroscopies, EPR and SQUID measurements. Salt 1 exhibits a 3-D supramolecular framework based on [Cr(C2O4)3]3- and 2-amino-4,6-dimethylpyridinim cations, (C7H11N2)+, via N–H···O hydrogen bonds. Interestingly, π–π stacking interactions between pyridine rings contribute to the stabilization of the crystal packing. In contrast to salt 1, no π–π stacking interactions are observed in the mixed-cation salt 2 and its crystal packing is consolidated by N–H···O and O − H···O hydrogen bonds. EPR spectra of 1 and 2 are consistent with the oxidation state +3 of the chromium center in an octahedral environment. Temperature-dependence of the magnetic susceptibility data investigated from 2 to 300 K revealed the existence of zero-field splitting effects (ZFS) for Cr(III) ions in both compounds.

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Accepted/In Press date: 27 December 2020
e-pub ahead of print date: 1 March 2021
Additional Information: Funding Information: This work was financially supported by the UK Engineering and Physical Sciences Council funding for the UK National Crystallography Service. The authors thank Prof. Augustin Ephraim Nkengfack (Organic Chemistry Department, University of Yaounde I, Cameroon) for the donation of organic reagents. Publisher Copyright: © 2021 Informa UK Limited, trading as Taylor & Francis Group. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
Keywords: crystal structures, Hybrid salts, magnetism, oxalate chromium(III) complex, stoichiometry

Identifiers

Local EPrints ID: 450830
URI: http://eprints.soton.ac.uk/id/eprint/450830
ISSN: 0095-8972
PURE UUID: c4eb6d12-b347-4302-82c6-406d8a7ee10a
ORCID for Simon J. Coles: ORCID iD orcid.org/0000-0001-8414-9272

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Date deposited: 13 Aug 2021 16:34
Last modified: 26 Nov 2021 02:42

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Contributors

Author: Coustel M.N. Choubeu
Author: Bridget N. Ndosiri
Author: Hervé Vezin
Author: Claire Minaud
Author: James B. Orton
Author: Simon J. Coles ORCID iD
Author: Justin Nenwa

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