Field-Induced Slow Magnetic Relaxation in Co^II Cyclopropane-1,1-dicarboxylates

New CoII substituted malonate field-induced molecular magnets {[Rb6Co3(cpdc)6(H2O)12]∙6H2O}n (1) and [Cs2Co(cpdc)2(H2O)6]n (2) (where cpdc2− stands for cyclopropane-1,1-dicarboxylic acid dianions) were synthesized. Both compounds contain mononuclear bischelate fragments {CoII(cpdc)2(H2O)2}2− where the quasi-octahedral cobalt environment (CoO6) is complemented by water molecules in apical positions. The alkali metal atoms play the role of connectors between the bischelate fragments to form 3D and 2D polymeric structures for 1 and 2, respectively. Analysis of dc magnetic data using the parametric Griffith Hamiltonian for high-spin CoII supported by ab initio calculations revealed that both compounds have an easy axis of magnetic anisotropy. Compounds 1 and 2 exhibit slow magnetic relaxation under an external magnetic field (HDC = 1000 and 1500 Oe, respectively).