A convenient MnIII starting material for the synthesis of homo- and heterometallic manganese carboxylate clusters: Mn9 and Mn10?xFex complexes

The use of a convenient source of Mn^III ions, namely the Mn(OR)(O₂CR′)₂]_n (R = H, Me, and R′ = Me, Bu^t) family of 1-D coordination polymers, afforded two new enneanuclear and decanuclear molecular clusters, homometallic Mn₉O₇(O₂CBu^t)₁₃(MeCN)₂] (3) and heterometallic Mn_10?xFe_x(OMe)₂₀(O₂CMe)₁₀] (x < 10) (4), respectively. Compound 3 was synthesized by a solvent-induced structural transformation, whereas complex 4 resulted from the reaction of Mn(OH)(O₂CMe)₂]_n with an Fe^III source. The core of 3 comprises two Mn₄O₂]⁸⁺ butterfly units and a Mn₃O]⁷⁺ triangular unit fused together by sharing one Mn atom. Magnetic susceptibility measurements of 3 revealed dominant antiferromagnetic interactions within the molecule, and a ground state of S = 1 with many low-lying excited states. Complex 4 is a mixed Fe^III/Mn^III single-strand molecular wheel, which forms 3D nanotubular stacks arranged in a zig–zag fashion. The described work suggests that the Mn(OR)(O₂CR′)₂]_n compounds represent excellent starting materials for Mn^III carboxylate cluster chemistry.