Syntheses, structures, and magnetic properties of tetramanganese(III) and hexamanganese(III) complexes containing derivative of biguanidate ligand: ferromagnetic interaction via imino nitrogen.

The tetramanganese(III) and hexamanganese(III) complexes, [Mn(4)(mu-pzbg)(2)(Hpzbg)(2)(MeO)(4)(MeOH)(H(2)O)]Cl(2) (1) and [Mn(6)O(4)(Hpzbg)(4)(AcO)(4)(MeO)(2)] (2), were synthesized by using a monopyrazolyl biguanide derivative (H(2)pzbg) as a multinucleating ligand, which was newly prepared by the nucleophilic addition of pyrazole to Dicyandiamide. Single-crystal X-ray analysis revealed that 2 possesses a face-sharing double cubane structure, in which six Mn(III) ions are bridged by six MeO(-) with four terminal kappa(2)N-Hpzbg(-). On the other hand, 1 possesses an incomplete face-sharing double cubane structure in which four Mn(III) ions are bridged by four MeO(-) and two kappa(2)N:kappa(2)N-pzbg(2-) accompanied by two terminal kappa(2)N-Hpzbg(-). In 1, both ferromagnetic and antiferromagnetic interactions occur between manganese(III) ions, of which the ferromagnetic one is assigned to be the interaction via the imino nitrogen atom, while all manganese(III) ions are connected in an antiferromagnetic manner in 2.