| Abstract
| - Two main questions are addressed in this study: (i) What increase of exchange interaction canbe expected when replacing a paramagnetic metal ion with a heavier congener located farther down theperiodic table (i.e., 3d−4d−5d), and (ii) for a molecular unit with higher coordination numbers, eight in thepresent case, how is the magnetic information transferred from the metal ion to its ligand set? Qualitativeand quantitative investigations on a series of trimetallic cyano-bridged {MoV(CN)8−NiII} and {WV(CN)8−NiII} compounds revealed ferromagnetic interactions but with a strength modulated by the spin organizationand their nature. DFT calculations have been used to examine the mechanism and strengths of the exchangecoupling, as well as the influence of the local symmetry of the cyanometalate unit on the spin densitydistribution. Both the experimental and the calculated behaviors underline a noticeable difference betweenthe Mo and the W derivatives (JMoNi = 26.9 cm-1 and JWNi = 37.3 cm-1) that is correlated to the spindensity transferred from the metal center to its ligand set. It is also shown that the shape of the {M(CN)8}polyhedron may lead to nonequivalent CN sites and, consequently, to different strengths of the exchangeinteraction as a result of the position of the bridging ligands.
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