Solvatomagnetic Studies on Cyano‐Bridged Bimetallic Chains Based on [Mn(cyclam)]3+ and Hexacyanometallates

Abstract

Structures and solvatomagnetic properties of two 1D CN‐bridged assemblies based on the complex [Mn(cyclam)]3+ (cyclam = 1,4,8,11‐tetraazacyclotetradecane) were characterised. The isostructural {[Mn(cyclam)][Cr(CN)6]·6H2O}n (1·6H2O) and {[Mn(cyclam)][Fe(CN)6]·6H2O}n (2·6H2O) chains crystallise in the space group C2/m. When dried in air at a slightly elevated temperature the hexahydrates undergo irreversible partial dehydration to stable dihydrates 1·2H2O and 2·2H2O. The structure model of 1·2H2O proposed from the powder XRD data shows lower symmetry of the network, described by the space group P21, and a markedly different relative arrangement of the chains. The Mn–Cr chains are characterised by antiferromagnetic (AFM) exchange through the CN bridges (J = –2.8 K for 1·6H2O and –6.0 K for 1·2H2O), which was modelled by quantum Monte Carlo simulations. Together with weaker AFM Mn–Cr interactions between the chains, it leads to ferrimagnetic ordering. FM intrachain interactions (J = 4.5 K for 2·6H2O and 7.1 K for 2·2H2O) and AFM 3D ordering are observed for the Mn–Fe chains. The dehydration process in both compounds causes an increase in the strength of magnetic exchange, which reflects changes in the CN bridge geometry.