Manganese(III) Porphyrin-Based Magnetic Materials

Manganese(III) porphyrin complexes with various metal-containing/non-metal bridges reported during the past two decades, including their structural characteristics and magnetic properties, are summarized. As the porphyrin ligands usually adopt a planar chelate form, it is possible that the porphyrin-based complexes, being a coordination-acceptor building block, have two coordination labile sites in trans positions. In particular, the coordination labile sites in an octahedral field face the direction of the Jahn-Teller elongated axis occupying the d_z2 orbital. As a result of this characteristic orbital arrangement, the activity and magnetic-electronic properties of the manganese complexes can be tuned by modulating the porphyrin ligand, which is equatorially located around the manganese ion and coupled with the d_x2-y2 orbital. The high-spin Mn(III) porphyrin complexes (S = 2) display strong magnetic uniaxial anisotropy with the Jahn-Teller axis as the magnetic easy axis. So far, various manganese(III) porphyrin magnetism systems, including multinuclear clusters, one-dimensional chains, and two- or three-dimensional networks, have been designed and structurally and magnetically characterized. This review shows that the manganese(III) porphyrin complexes have potential as versatile sources for the design of unique magnetic materials as well as other molecular functional materials with various structures.