Tetracyanoethylene-based organic magnets

Several classes of organic magnets based upon the tetracyanoethenide radical anion, [TCNE](.-), either unbound, mu, and mu(4) bonded to zero, two and four metal sites have been reported. The putative mu(4) bonded V(TCNE)(x) room temperature magnet has been extended to include M(TCNE)(x) (M = Mn, Fe, Co, Ni) magnets. M for this class of magnets is assigned to be in the divalent oxidation state. A sigma-[TCNE](2)(2-) dimer intermediate has been isolated. The intrachain magnetic coupling for the 1-D coordination polymers having [TCNE](.-) mu-bridge bonded to [Mn(III)porphyrins](+) is discussed in the context of a structure-function correlation arising from the dihedral angle between the [(MnTPP)-T-III](+)'s MnN4 and [TCNE](.-) mean planes and the magnitude of magnetic coupling. This correlation is ascribed to the increasing importance of the sigma-Mn-III d(z2)/[TCNE](.-) p(z) overlap with decreasing dihedral angle.