The molecular and electronic structures of monomeric cobalt complexes containing redox noninnocent o-aminobenzenethiolate ligands

Sproules, S. , Kapre, R. R., Roy, N., Weyhermüller, T. and Wieghardt, K. (2010) The molecular and electronic structures of monomeric cobalt complexes containing redox noninnocent o-aminobenzenethiolate ligands. Inorganica Chimica Acta, 363(12), pp. 2702-2714. (doi:10.1016/j.ica.2010.03.042)

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Abstract

Dark blue [PPh4][CoIII(2L)] (2), where (2L)2− represents the closed-shell dianion of 4,6-di-tert-butyl-2-[(pentafluorophenyl)amino]benzenethiol, has been synthesized from the reaction of H2(2L) and CoCl2 (2:1) in acetonitrile with excess NEt3, brief exposure of the solution to air, and addition of [PPh4]Br. The oxidation of 2 with one equivalent of iodine produces the neutral species [CoIII(2Lradical dot)2I]0 (3), where (2Lradical dot)1− represents the one-electron oxidized π radical anion of (2L)2−. Crystalline [CoIII(4Lradical dot)] (4), where (4Lradical dot)3− is the π radical monoanion of bis-2,2′-(1,2-diphenylethylenediimine)-benzenethiolate, was precipitated from a toluene reflux of [CoII(3L)2], where (3L)2− is the closed-shell monoanion of 2-(phenylmethylamino)benzenethiol. The reduction of 4 with CoCp2 under anaerobic conditions yielded dark violet crystals of [CoCp2][CoIII(4L)] (5). The reaction of Zn(CH3CO2)2 with 2-phenylbenzothiazoline in methanol resulted in the formation of [ZnII(3L)2]0 (6). The two monoanions 2, and 5, along with [N(n-Bu)4][Co(abt)2] (1) (abt2− = o-aminobenzenethiolate), and neutral 4 have all been shown by X-ray crystallography to be square planar. A tetrahedral geometry was adopted by 6. From temperature dependent (3–300 K) magnetic susceptibility measurements, it was established the monoanions have a triplet ground state characterized by a large zero field splitting. EPR measurements of 4, and electrochemically oxidized 1 and 2 reveal distinctly different spin Hamiltonian parameters that are interpreted with the aid of density function theoretical (DFT) calculations. It is shown that oxidation states describing a d6 Co(III) or d7 Co(II) cannot be unambiguously assigned for these neutral and monoanionic species.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Sproules, Dr Stephen
Authors: Sproules, S., Kapre, R. R., Roy, N., Weyhermüller, T., and Wieghardt, K.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Inorganica Chimica Acta
Publisher:Elsevier
ISSN:0020-1693
ISSN (Online):1873-3255

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