Reactions between macrocyclic nickel(II) complexes and ferricyanide. Metamagnetic properties of a two-dimensional honeycomb assembly [NiL3]3[Fe(CN)6]2·8H2O (L3 = 3,10-dihydroxyethyl-1,3,6,8,10,12-hexaazacyclotetradecane)

Abstract

The synthesis, structural and magnetic properties of the 2-D bimetallic complex [NiL³]₃[Fe(CN)₆]₂·8H₂O (L³ = 3,10-dihydroxyethyl-1,3,6,8,10,12-hexaazacyclotetradecane) are presented. The structure consists of cyano-bridged neutral honeycomb-like layers. Each hexacyanoferrate(III) ion connects three nickel(II) ions using three cis CN⁻ groups and the remaining CN⁻ groups are terminal. The bridging cyanide ligands coordinate to the nickel ion in a trans fashion. Magnetic studies showed that the complex displays a metamagnetic behaviour arising from intralayer ferromagnetic coupling and interlayer antiferromagnetic interactions. A long-range magnetic ordering at T_c = 6.0 K was observed. In addition, the ionic complex [NiL⁴]₃[Fe(CN)₆]₂·6H₂O (L⁴ = 8-methyl-1,3,6,8,10,13,15-heptaazatricyclo[13.1.1.1^13,15]octadecane) showing the absence of cyano bridging, is reported.