Among the mononuclear 3d transition metal complexes, high-spin (S = 3/2) cobalt(II) coordination complexes are known to show slow relaxation of magnetization in different coordination (four, five, six coordinated) environments.1 In the present work, we have used H2bip (2,2′-bi-1,4,5,6-tetrahydropyrimidine, a bidentate diimine ligand) to coordinate with Co(II), resulting in a coordinatively-diverse family of Co(H2bip)nX2 (n = 1, 2, 3; X = Cl and Br) compounds: (a) [Co(H2bip)Cl2] (n = 1), (b) [Co(H2bip)2Cl2] (n= 2), (c) [Co(H2bip)2Br2] (n= 2), and (d) [(H2bip)3Co](Br)2 (n= 3). In the presence of the H2bip ligand environment, all of the compounds show field-induced slow relaxation of magnetization. The TD-DFT calculations of the low-lying excited-state energies show the relaxation of the cobalt complexes are mostly due to the ionic anisotropy of the Co(II) center and not significantly influenced by the particular ligand field environment. Recently, we have prepared heteroleptic Co(II) complexes, including [(H2bip)2Co(4,4'-Mebpy)]Br2, where the dipyridyl moiety should significantly increase the ligand field around the metal center. Investigations of ligand field influences on the magnetic properties of these and related complexes will be presented. [1] Some most recent examples: (a) Boca, R.; Miklovic, J.; Titis, J. Inorg. Chem. 2014, 53, 2367. (b) Herchel, R.; Váhovská, L.; Potočňák, I.; Trávníček, Z. Inorg. Chem. 2014, 53, 5896.

Ligand field modification of cobalt-H2bip complexes to control field induced magnetic relaxations

249th National Meeting (2015)

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