Relationship Between the Nearest‐Neighbor Exchange Coupling Constants and the Number of Exchange Interactions in the Cyano‐Bridged MnMo6(CN)18 Cluster: Density Functional Theory Calculations

Abstract

AbstractA theoretical density functional study of the relationship between the nearest‐neighbor MnMo constants and the number of exchange interactions in the cyano‐bridged K[(Me3tacn)6MnMo6(CN)18](ClO4)3 cluster is presented. Two approaches (the first approach consisted of evaluating the exchange coupling constant Jij between two paramagnetic metal centers i and j in the hexanuclear molecule by calculating the energy differences between the highest and broken‐symmetry spin states of a model molecule in which metal atoms except for i and j are substituted by diamagnetic YIII cations, and the second is to calculate the different spin‐state energies of hexanuclear complexes and use the Heisenberg Hamiltonian to obtain the exchange coupling constants between different metal centers) show that the antiferromagnetic coupling interactions between nearest neighbors weaken with the increase of the number of exchange interactions. The various θ angles have an influence on the interactions between the nearest‐neighbor MoMn but do not change the trend between J12 and the number of exchange interactions. Moreover, Kahn’s qualitative theory succeeded in being applied to interpret the trend.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)