A manganese(III) complex that exhibits spin crossover behavior

A novel MnIII(d4) complex, which exhibit spin crossover (SCO) phenomenon arising from the spin transition of LS ↔ HS state, was characterized structurally as well as magnetically. Single crystal X-ray diffraction methods structurally determined the compound as [MnIII(OL1)2]Cl · 3H2O. Two facially coordinating tridentate ligands are bound to the manganese(III) ion, resulting in an MnN4O2 chromophore with an axially-compressed octahedral geometry. The nitrogen donors are all in the equatorial plane with Mn–N distances ranging from 2.14 to 2.19 Å, the two oxygen donors occupy the axial positions at 1.86 Å. Magnetic susceptibilities were measured between 77 and 300 K. At 77 K, the magnetic moment converges close to the expected low spin (LS) value of 2.8 μB, whereas at 300 K the high spin (HS) limit is entropically inaccessible, as this is a one-electron SCO.

Graphical abstractA MnIII(d4) complex, [MnIII(OL1)2]Cl · 3H2O was characterized structurally as well as magnetically. The two tridentate ligands are bound to the manganese(III) ion, resulting in an MnN4O2 chromophore with an axially-compressed octahedral geometry. Magnetic susceptibilities were measured and spin crossover (SCO) phenomenon arising from the spin transition of MnIII is exhibited.Figure optionsDownload full-size imageDownload as PowerPoint slide