Study of multinuclear f-electronic structures by a multidimensional non-linear optimization method

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The computational method which Ishikawa previously proposed for determination of sublevel structure of ground multiplets of isostructural series of lanthanide complexes was applied to several representative classes of lanthanide complexes. The new information about electronic structures of the 4f-complexes led to new physico-chemical aspects of lanthanide complexes as follows.(1)Ligand field parameters and ground multiplet structures have been determined for bis(phthalocyaninato)lanthanides Pc_2Ln^- and tris(dipicolinato)lanthanides Ln(dipic)_3^<3->. Temperature dependence of magnetic susceptibilities and NMR data of these complexes were quantitatively elucidated based on the quantum-chemical view for the first time.(2)Ligand field parameters of the tris(phthalocyaninato) dinulear lanthanide complexes Pc_3Ln_2 were determined. This led to the elucidation of the nature of the f-f interaction between the two lanthanide ions in the complexes.(3)SMM behavior of single-ionic lanthanide comp … More lex was discovered for Pc_2Tb^- and Pc_2Dy^-.(4)The π-radical Pc_2Tb^0 showed SMM behavior at even higher temperature range by 10K than the anionic complex. In the π-radical SMM, two spin system, S_z=(+1/2,-1/2) and J_z=(+6,-6) are present in a single molecule, leading to the pi-f interaction that yields this remarkable effect.(5)The contribution of the f-f interaction to the dynamical magnetism of the dinuclear terbium complexes Pc_3Tb_2 was elucidated both experimentally and theoretically.(6)Magnetic susceptibility measurements in the sub-kelvin range revealed that Pc_2Tb^-, Pc_2Dy^- and Pc_2Ho^- exhibit staircase-like structures in magnetization hysteresis curves. These structures are caused by the quantum-tunneling of magnetization (QTM).(7)Ln(dipic)_3^<3-> with odd numbers of 4f-elections exhibited significant dc-magnetic field dependences of ac susceptibilities. While none of the six heavy-lanthanide complexes showed magnetization lag from ac magnetic field of 10 - 10^3 Hz above 1.7K, the Dy, Er and Yb complexes with odd numbers of 4f-electrons exhibited the magnetization lag in a dc field. Less