Yao, Jing-cai, Guo, Jin-bo, Wang, Jian-ge, Wang, Yu-fang, Zhang, Li, and Fan, Cui-ping
Abstract: Two new 3d-4f complexes, [LnCo(3,5-pdc)2(3,5-Hpdc) (H2O)7]·H2O (Ln=Gd 2, La 3; 3,5-pdcH2 =pyridine-3,5-dicarboxylic acid), have been synthesized by the self-assembly of Ln(III) oxides, 3,5-pdcH2 and the template molecule [Co(3,5-pdc)(H2O)5]·H2O (1) under hydrothermal conditions. Heterometallic complexes 2 and 3 are isostructural with supracyclic units containing four Ln(III) ions and two Co(II) ions, in which Co(II) and Ln(III) are linked by the deprotonated 3,5-pdcH2 ligands in three kinds of bridging modes. The weak antiferromagnetic coupling of complex 2 and 3 imply that the large 3,5-pdc bridges with the greater separation ( >7Å) cannot lead to long range magnetic ordering, the strength of d n -f n exchange coupling increasing with decreases the size of the lanthanide ion. [ABSTRACT FROM AUTHOR]