Magnetostructural correlations in Cu(II)-NC-W(V) linkage: the case of [Cu(II)(diimine)]2+-[W(V)(CN)8]3- 0D assemblies.

We report on the syntheses, crystal structures, and magnetic properties of two cyano-bridged molecular assemblies: Cu(II)(phen)(3){Cu(II)(phen)(2)W(V)(CN)(8)}(ClO(4))(2) x 10 H(2)O (phen = 1,10-phenanthroline) (1) and {Cu(II)(bpy)(2)[W(V)(CN)(8)]} {[Cu(II)(bpy)(2)][W(V)(CN)(8)]} x 4 H(2)O (bpy = 2,2'-bipyridyl) (2). Compound 1 consists of cyano-bridged Cu(II)(2)W(V)(2) molecular rectangles and isolated Cu(II)(phen)(3) complexes. The molecular structure of 2 reveals cyano-bridged trinuclear Cu(II)(2)W(V) and dinuclear Cu(II)W(V) ions. Magnetic interactions in 1 are interpreted in terms of the model of a tetranuclear moiety consisting of two ferromagnetic Cu(II)-NC-W(V) units (J(1) = +39(4) cm(-1)) interacting antiferromagnetically (J(2) = -1.6(4) cm(-1)). The analysis of the magnetic response of 2 reveals ferromagnetic interaction within the Cu(II)-NC-W(V)-CN-Cu(II) and Cu(II)-NC-W(V) isolated units, characterized by J = +35(7) cm(-1) and antiferromagnetic coupling between them (4J' = -0.30(8) cm(-1)). The discussion of the magnetic behavior and the correlation of the J(CuW) parameters with the geometry of cyano bridges at copper(II) centers of 1 and 2 is based on the DFT calculations, which yield J(av) = +13.2 cm(-1) for 1 and J = +31 cm(-1) for 2. The domination of the ferromagnetic Cu(II)-NC-W(V) interaction in 1 and 2 originates from the mutual orthogonality of natural magnetic orbitals in the case of coordination of cyano bridges at the equatorial sites of Cu(II) moieties.