Magneto Structural Correlations in Discrete MnII-WV Cyano-Bridged Assemblies with Polyimine Ligands

We present the magneto-structural correlations for two novel discrete cyano-bridged assemblies based on cationic complexes of manganese(II) with diimine ligands and octacyanotungstate(V) ions. The crystal structure of [Mn-II(terpy)(dmf)(H2O)(2)][Mn-II(terpy)(H2O)(dmf)(mu-NC)W-V(CN)(7)](2) center dot 6H(2)O (1) (terpy = 2,2';6',2 ''-terpyridine, dmf = dimethylformamide) contains dinuclear [(MnWV)-W-II}(-) cyano-bridged anions, while the crystal structure of [Mn-II(phen)(3)](2)[Mn-II(phen)(2)(mu-NC)(2)-W-V(CN)(6)](2)(ClO4)(2) center dot 9H(2)O (2) (phen = 1,10-phenanthroline) is built of tetranuclear ((Mn2W2V)-W-II}(2-) square anions. Intramolecular Mn-W magnetic interactions through the cyano bridges are represented by magnetic coupling constants J = -39 cm(-1) for the {(MnWV)-W-II)(-) unit in 1 and J(1) = -25.7 and J(2) = -16.7 cm(-1) for the {(Mn2W2V)-W-II}(2-) unit in 2. J and J(1) represent relatively strong W-CN-Mn interactions and are ascribed to the bridges in b positions of TPRS-8 (trigonal prism squareface bicapped) of [W(CN)(8)](3-) polyhedra, favoring the strongest electronic interactions between the d(z2)-d(x2)_(y2) orbital of W and the pi(center dot) orbitals of CN-, whereas J(2) is related to the m vertex of [W(CN)(8)](3-). The magnetic properties of 1 and 2 are compared with reference compounds and discussed in the context of the type of coordination polyhedra of [W(CN)(8)](3-) as well as the metric parameters of cyano-bridged W-CN-Mn linkages. We found the type of coordination polyhedra and bridging mode of [W(CN)(8)](3-) to be the most important factors influencing the magnitude of the Mn-W magnetic interaction.