X-ray structure and spectroscopic properties of pentasodium bis(l-tartrato(4-)-O1,O2,O3) manganate(III) dodecahydrate

X-ray crystallographic analysis of Na5[Mn(l-tart)2] · 12H2O demonstrated that Mn(III) ion has two tridentate l-tartrates of which two deprotonated hydroxo groups and one carboxylate are coordinated in contrast to the previously proposed structure with two didentate tartrates and two coordinated water. The tetragonally distorted octahedron due to the Jahn–Teller effect was discussed in relation with the large splitting components for the UV–Vis and circular dichroism (CD) spectra in the d–d transition in the solid. The significant difference in the UV–Vis and CD spectra between the solid and the solution suggests that the tridentate coordination of the tartrate in the solid complex changes to the didentate one in the solution.