Crystal Structures and Magnetic Behaviors of Cyanido‐Bridged Dinuclear Dimetallic Systems Involving 3d–3d or 3d–5d Metal Centers

Abstract

AbstractThree cyanido‐bridged FeIII–MnII dimers, [Fe(pzcq)(CN)3][Mn(phen)2(X)]·MeOH [X = Cl (1), Br (2); pzcq = 8‐(pyrazine‐2‐carboxamido)quinoline anion, phen = 1,10‐phenanthroline], [Fe(mpzcq)(CN)3][Mn(phen)2(Cl)]·MeOH [3; mpzcq = 8‐(5‐methylpyrazine‐2‐carboxamido)quinoline anion], and one WV–MnII dinuclear system, [W(bpy)(CN)6][Mn(phen)2(Cl)]·MeOH (4; bpy = 2,2′‐bipyridine), were prepared by assembling molecular precursors, [Fe(pzcq)(CN)3]–, [Fe(mpzcq)(CN)3]–, and [W(bpy)(CN)6]–, with Mn(phen)2X2. The absolute configurations of the Mn polyhedra surrounded by two bidentate phen ligands are packed in a –Δ–Λ–Δ–Λ– sequence in the crystal lattice. The aromatic rings of the coordinated phen ligands are sources of considerable interdimer π–π contacts, which eventually lead to the formation of two‐dimensional frameworks (1–3) and a one‐dimensional chain structure (4). Magnetic analyses of the FeIII–MnII dinuclear systems (1–3) reveal that a shorter Mn–N(cyanide) bond and a more linear Mn–N–C(cyanide) angle allow for stronger magnetic exchange coupling. Moreover, it is manifested that the 3d–5d magnetic coupling in 4 is stronger than the 3d–3d coupling in 1–3 under the given structural environments, which is due to the fact that the 5d orbital is more diffuse than the 3d orbital. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)