Pentacoordinate and Hexacoordinate Mn(III) Complexes of Tetradentate Schiff-Base Ligands Containing Tetracyanidoplatinate(II) Bridges and Revealing Uniaxial Magnetic Anisotropy.

Crystal structures and magnetic properties of polymeric and trinuclear heterobimetallic Mn···Pt···Mn coordination compounds, prepared from the Ba[Pt(CN)₄] and [Mn(L4A/B)(Cl)] (/) precursor complexes, are reported. The polymeric complex [{Mn(L4A)}₂{μ⁴-Pt(CN)₄}] (), where H₂L4A = ,'-ethylene-bis(salicylideneiminate), comprises the {Mn(L4A)} moieties covalently connected through the [Pt(CN)₄] bridges, thus forming a square-grid polymeric structure with the hexacoordinate Mn atoms. The trinuclear complex [{Mn(L4B)}₂{μ-Pt(CN)₄}] (), where H₂L4B = ,'-benzene-bis(4-aminodiethylene-salicylideneiminate), consists of two [{Mn(L4B)} moieties, involving pentacoordinate Mn atoms, bridged through the tetracyanidoplatinate (II) bridges to which they are coordinated in a fashion. Both complexes possess uniaxial type of magnetic anisotropy, with (the axial parameter of zero-field splitting) = -3.7(1) in and -2.2(1) cm in . Furthermore, the parameters of magnetic anisotropy and were also thoroughly studied by theoretical complete active space self-consistent field (CASSCF) methods, which revealed that the former is much more sensitive to the ligand field strength of the axial ligands.