Ferromagnetically coupled linear electron-transfer complexes. Structural and magnetic characterization of [Cr(.eta.6-C6MexH6-x)2][TCNE] (x = 0,3,6) and S = 0 [TCNE]22-

The reaction of Cr{sup 0}(C{sub 6}Me{sub x}H{sub 6-x}){sub 2} (x = 0, 3, 6), D, with TCNE, A, results in formation of 1:1 electron-transfer salts of (Cr{sup 1}(C{sub 6}Me{sub x}H{sub 6-x}){sub 2})(TCNE) (x = 0, 3, 6) composition. The x = 0 and 3 complexes have been structurally characterized. The magnetic susceptibility between 2 and 320 K for these (TCNE){sub 2}{sup 2{minus}} complexes can be fit by the Curie-Weiss law, {chi} = C/(T-{theta}), for one independent per spin repeat unit. Charge-transfer excitation from the next highest occupied molecular orbital is consistent with the stabilization of ferromagnetic coupling for this system. Thus, other molecular/organic systems with {sup 2}A ground states might be suitable components for a bulk ferromagnet.