Rational and systematic syntheses and physical properties of 3d-4f mixed metal complexes

点击翻译按钮获取中文摘要

In this research program, we focused on establishment of rational synthesis method for 3d-4f mixed metal complexes and systematic investigation of their physical properties. Principal results during 2000-2002 are as follows.1. M^<II>-Ln^<III>-M^<II> type trinuclear complexes, [M_2Ln(L)_2(NO_3)_3] (M^<II> = Mn, Fe, Co, Ni, Cu, Zn ; Ln^<III> = La, Ce, ... Yb, Lu), were successfully obtained from a 'one-pot' reaction of a ligand, 1, 1'-(2, 6-pyridylene)-bis(l, 3-butanedione) (H_2L), M(NO_3)_2nH_2O and Ln(NO_3)_3nH_2O with using of difference of ion radius.2. Crystal structures of most of complexes were determined. Two L^<2-> providing one central 2, 6-diacylpyridine site and two terminal 1, 3-diketonate sites hold two M^<II> ions and Ln^<III> ion and form a linear M-Ln-M trinuclear core in all complexes. The planarity of the trinuclear core changes with the Ln^<III> ion. The dihedral angle between two pyridine rings increases with decreasing ion radius of central Ln^<III>.3. Antiferromagnetic interaction operates between M^<II> and Ln^<III> (f^1 - f^6). On the other hand, magnetic interaction between M^<II> and Ln^<III> (Gd, Dy, Tb) are clearly ferromagnetic. However, the other lanthanide ion shows antiferromagnetic behavior because of dominant spin-orbit coupling.4. Novel trimetallic assemblies, [M_2Gd(L)_2][Cr(CN)_6]・nH_2O, were prepared by the reaction of the trinuclear complexes, [M_2Ln(L)_2(NO_3)_3], and [Cr(CN)_6]^<3->. The assembled structure was 1-D chain for M = Cu, 2-D sheet for M = Ni, and 3-D network for M =Co, respectively. In the case of M = Ni and Co, magnetic ordering was achieved. Furthermore, CoLn-Cr assemblies show ferro-, ferri- and meta-magnetic ordering depending on the central Ln^<III> ions.