Mixed transition-metal-lanthanide complexes at higher oxidation states: heteronuclear CeIV-MnIV clusters.

Abstract

The syntheses of the first mixed-metal CeIVMnIV complexes are reported. [CeMn2O3(O2CMe)(NO3)4(H2O)2(bpy)2](NO3) (1; bpy = 2,2‘-bipyridine) was obtained from the reaction of Mn(NO3)2·xH2O and bpy with (NH4)2Ce(NO3)6 in a 1:1:2 molar ratio in 25% aqueous acetic acid. The complexes [CeMn6O9(O2CR)9(X)(H2O)2]y+ (R = Me, X = NO3-, y = 0 (2); R = Me, X = MeOH, y = +1 (3); R = Et, X = NO3-, y = 0 (7)) were obtained from reactions involving a [Mn(O2CR)2]·4H2O/CeIV ratio of ∼1:1.5 in concentrated aqueous carboxylic acid. A related reaction in less-concentrated aqueous acetic acid and in the presence of L (where L = 2-hydroxy-6-methylpyridine (mhpH), 2-pyrrolidinone (pyroH), or pyridine (py)) gave [Ce3Mn2O6(O2CMe)6(NO3)2(L)a(H2O)b] (L = mhpH, a = 4, b = 0 (4); L = pyroH, a = 2, b = 3 (5)) and {{(pyH)3[Ce3Mn2O6(O2CMe)7.5(NO3)3]·(HO2CMe)0.5·(H2O)2}2(NO3)}n (6), respectively. Solid-state magnetic susceptibility (χM) data for compounds 1, 4, and 5 were fit to the theoretical χMT versus T expression for a MnIV2 complex d...