Highly anisotropic exchange interactions in a trigonal bipyramidal cyanide-bridged Ni(II)3Os(III)2 cluster

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 113; no. 25; pp. 6886 - 6890
• Main Authors: Palii, Andrei V, Reu, Oleg S, Ostrovsky, Sergei M, Klokishner, Sophia I, Tsukerblat, Boris S, Hilfiger, Matthew, Shatruk, Michael, Prosvirin, Andrey, Dunbar, Kim R
• Format: Journal Article
• Language: English
• Published: United States 25.06.2009
• Subjects: Anisotropy; Magnetics; Models, Molecular; Nickel - chemistry; Nitriles - chemistry; Organometallic Compounds - chemistry; Osmium - chemistry; Temperature
• ISSN: 1520-5215
• DOI: 10.1021/jp902197n

This article is a part of our efforts to control the magnetic anisotropy in cyanide-based exchange-coupled systems with the eventual goal to obtain single-molecule magnets with higher blocking temperatures. We give the theoretical interpretation of the magnetic properties of the new pentanuclear complex {[Ni(II)(tmphen)(2)](3)[Os(III)(CN)(6)](2)} x 6 CH(3)CN (Ni(II)(3)Os(III)(2) cluster). Because the system contains the heavy Os(III) ions, spin-orbit coupling considerably exceeds the contributions from the low-symmetry crystal field and exchange coupling. The magnetic properties of the Ni(II)(3)Os(III)(2) cluster are described in the framework of a highly anisotropic pseudo-spin Hamiltonian that corresponds to the limit of strong spin-orbital coupling and takes into account the complex molecular structure. The model provides a good fit to the experimental data and allows the conclusion that the trigonal axis of the bipyramidal Ni(II)(3)Os(III)(2) cluster is a hard axis of magnetization. This explains the fact that in contrast with the isostructural trigonal bipyramidal Mn(III)(2)Mn(II)(3) cluster, the Ni(II)(3)Os(III)(2) system does not exhibit the single-molecule magnetic behavior.