Slow Magnetic Relaxation in a Series of Mononuclear 8-Coordinate Fe(II) and Co(II) Complexes.

['Jin XX', 'Chen XX', 'Xiang J', 'Chen YZ', 'Jia LH', 'Wang BW', 'Cheng SC', 'Zhou X', 'Leung CF', 'Gao S']
Inorg Chem. 2018 Mar 9. doi: 10.1021/acs.inorgchem.7b03071. [Epub ahead of print]

Author information
['College of Chemistry and Environmental Engineering , Yangtze University , Jingzhou 434020 , HuBei , P. R. China.', 'State Key Laboratory of Rare Earth Materials Chemistry and Applications and PKU-HKU Joint Laboratory on Rare Earth Materials and Bioinorganic Chemistry , Peking University , Beijing 100871 , P. R. China.', 'School of Chemistry and Environmental Engineering , Wuhan Institute of Technology , Wuhan 430073 , P. R. China.', 'Department of Chemistry , City University of Hong Kong , Tat Chee Avenue, Kowloon Tong , Hong Kong 999077 , P. R. China.', 'Department of Science and Environmental Studies , The Education University of Hong Kong , 10 Lo Ping Road, Tai Po, NT , Hong Kong 999077 , P. R. China.']

Abstract
['A series of homoleptic mononuclear 8-coordinate FeII and CoII compounds, [FeII(L2)2](ClO4)2 (2), [FeII(L3)2](ClO4)2 (3), [FeII(L4)2](ClO4)2 (4), [CoII(L1)2](ClO4)2 (5), [CoII(L2)2](ClO4)2 (6), [CoII(L3)2](ClO4)2 (7), and [CoII(L4)2](ClO4)2 (8) (L1 and L2 are 2,9-dialkylcarboxylate-1,10-phenanthroline ligands; L3 and L4 are 6,6'-dialkylcarboxylate-2,2'-bipyridine ligands), have been obtained, and their crystal structures have been determined by X-ray crystallography. The metal center in all of these compounds has an oversaturated coordination number of 8, which is completed by two neutral homoleptic tetradentate ligands and is unconventional in 3d-metal compounds. These compounds are further characterized by electronic spectroscopy, cyclic voltammetry (CV), and magnetic measurements. CV measurements of these complexes in MeCN solution exhibit rich redox properties. Magnetic measurements on these compounds demonstrate that the observed single-ion magnetic (SIM) behavior in the previously reported [FeII(L1)2](ClO4)2 (1) is not a contingent case, since all of the 8-coordinate compounds 2-8 exhibit interesting slow magnetic relaxation under applied direct current fields.']