Tuning of spin crossover properties in a series of mononuclear cobalt(ii) complexes based on a macrocyclic tetradentate ligand and pseudohalide coligands

Ghosh, S and Selvamani, S and Kamilya, S and Mehta, S and Mondal, A (2022) Tuning of spin crossover properties in a series of mononuclear cobalt(ii) complexes based on a macrocyclic tetradentate ligand and pseudohalide coligands. In: Dalton Transactions, 51 . pp. 9642-9652.

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Abstract

The three mononuclear cobalt(ii) complexes, [Co(L)(NCX)2] (L = N,N‘-di-tert-butyl-2,11-diaza[3,3](2,6)pyridinophane, and X = S (1), Se (2), and [C(CN)2] (3)), have been synthesized and characterized using variable temperature single-crystal X-ray crystallography, and spectroscopic, magnetic, and electrochemical studies. All three complexes have a similar distorted octahedral CoN6 coordination geometry produced by the macrocyclic tetradentate ligand L and two NCX− co-ligands in the cis position. Complexes 1 and 2 crystallized in the monoclinic P21/n (Z = 4) space group, while complex 3 was isolated in the monoclinic P21/c (Z = 4) space group. Interestingly, complexes 1 and 2 exhibit a reversible and gradual spin-crossover behavior between the high-spin (S = 3/2) and low-spin (S = 1/2) states at ca. 168 K and 255 K, respectively. However, for complex 3, a low-spin configuration persists up to 260 K and it exhibits an incomplete and reversible spin crossover even at 400 K. In addition, complex 1 displays a reversible redox behavior indicating the paramagnetic cobalt(ii) to diamagnetic cobalt(iii) conversion.

Item Type:	Journal Article
Publication:	Dalton Transactions
Publisher:	Royal Society of Chemistry
Additional Information:	The copyright for this article belongs to the Royal Society of Chemistry.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	02 Jul 2022 06:17
Last Modified:	02 Jul 2022 06:17
URI:	https://eprints.iisc.ac.in/id/eprint/74137

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