Modeling Spin Interactions in a Cyclic Trimer and a Cuboidal Co_4O_4 Core with Co(ll)in Tetrahedral and Octahedral Environments

摘要

The X-ray crystallographic structures,the magnetic susceptibilities from 2 to 300 K,and a theoretical analysis of the magnetism for a triangular and a tetranuclear molecule consisting of linked high-spin cobalt(ll)centers are described.The interpretation of the magnetic data for the triangular compound [Co(depa)CI]_3(depa is the anion of 2,2'-(bis-4-ethylpyridyl)amine),which has tetrahedrally coordinated Co~(2+)ions,entails isotropic antiferromagnetic exchange interaction and antisymmetric exchange acting within the two low-lying spin doublets.Two strong isotropic ferromagnetic interactions have been modeled in the cuboidal compound Co_4(DPM)_4(CH_3OMCH_3OH)_4(DPM represents the anion of dipivaloylmethane),which has octahedral coordination,and the system can be approximately considered as two weakly coupled S = 3 species.