Exploring the Sources of the Magnetic Anisotropy in a Family of Cyanide-Bridged Ni9Mo6 and Ni9W6 Systems: A Density Functional Theory Study.

A density functional theory (DFT) study of the magnetic coupling interactions and magnetic anisotropy in a family of experimentally synthesized Ni9MoV and Ni9WV systems is presented. Our calculations show that for all of our selected Ni9M6 systems, the intramolecular magnetic coupling interactions are ferromagnetic, and the ground-state spins are 12. All of the D values of Ni9W6 systems come mainly from the contribution of the Di of W6(CN)48Ni extracted from Ni9W6, and the influence of the eight surrounding Ni including the ligands on their magnetic anisotropy is very small. Although the surrounding Ni bounded by different ligands have a small influence on all D values for our selected complexes, they decide on the core structures of W6(CN)48Ni, which dominate their magnetic anisotropy. Thus, to obtain a Ni9W6 system having a large negative D, we can use different ligands bound to Ni to obtain a good core structure of W6(CN)48Ni with a large negative D value. All D values of Ni9Mo6 systems also come mainly from the contribution of Di of the Mo6(CN)48Ni, which is positive or negative but very small; most of these systems do not behave as single-molecule magnets. [ABSTRACT FROM AUTHOR]