Trapping of a pseudotetrahedral CoIIO4 core in mixed-valence mixed-ceometry [Co5] coordination aggregates: synthetic marvel, structures, and magnetism

Chattopadhyay, K., Heras Ojea, M. J., Sarkar, A., Murrie, M. , Rajaraman, G. and Ray, D. (2018) Trapping of a pseudotetrahedral CoIIO4 core in mixed-valence mixed-ceometry [Co5] coordination aggregates: synthetic marvel, structures, and magnetism. Inorganic Chemistry, 57(21), pp. 13176-13187. (doi:10.1021/acs.inorgchem.8b01577) (PMID:30351068)

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Abstract

A systematic one-step one-pot multicomponent reaction of Co(ClO4)2·6H2O, H3L (2,6-bis((2-(2-hydroxyethylamino)ethylimino)methyl)-4-methylphenol), and readily available carboxylate salts (RCO2Na; R = CH3, C2H5) resulted in the two structurally novel coordination aggregates [CoIICoIII4L2(μ1,3-O2CCH3)2(μ-OH)2](ClO4)4·4H2O (1) and [CoIICoIII4L2(μ1,3-O2CC2H5)2(μ-OH)(μ-OMe)](ClO4)4·5H2O (2). At room temperature, reactions of H3L in MeOH with cobalt(II) perchlorate salts led to coassembly of initially formed ligand-bound {CoII2} fragments following aerial oxidation of metal centers and bridging by in situ generated hydroxido/alkoxido groups and added carboxylate anions. Available alkoxido arms of the initially formed {L(μ1,3-O2CCH3)(μ-OH/OMe)Co2}+ fragments were utilized to trap a central CoII ion during the formation of [Co5] aggregates. In the solid state, both complexes have been characterized by X-ray crystallography, variable-temperature magnetic measurements, and theoretical studies. Both 1 and 2 show field-induced slow magnetic relaxation that arises from the single pseudo-Td CoII ion present. The structural distortion leads to an easy-axis magnetic anisotropy (D = −31.31 cm–1 for 1 and −21.88 cm–1 for 2) and a small but non-negligible transverse component (E/D = 0.11 for 1 and 0.08 for 2). The theoretical studies also reveal how the O–Co–O bond angles and the interplanar angles control D and E values in 1 and 2. The presence of two diamagnetic {Co2(μ-L)} hosts controls the distortion of the central {CoO4} unit, highlighting a strategy to control single-ion magnetic anisotropy by trapping single ions within a diamagnetic coordination environment.

Item Type:Articles
Additional Information:K.C. is thankful to the Council of Scientific and Industrial Research, New Delhi, India, for financial support. We are also thankful to the DST, New Delhi, Indian, for providing the single-crystal X-ray diffractometer facility at the Department of Chemistry, IIT Kharagpur, under its FIST program. M.M. thanks the University of Glasgow for financial support. G.R. thanks the SERB for its financial support (EMR/2014/ 000247).
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Murrie, Professor Mark and Heras Ojea, Miss Maria Jose
Authors: Chattopadhyay, K., Heras Ojea, M. J., Sarkar, A., Murrie, M., Rajaraman, G., and Ray, D.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Inorganic Chemistry
Publisher:American Chemical Society
ISSN:0020-1669
ISSN (Online):1520-510X
Published Online:16 October 2018

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