Fluoride assisted stabilization of manganese(III) in aqueous medium. Synthesis and spectral characterization of new mixed-Jigand fluoromanganate(III), containing hydroxy-carboxylic acids as ancillary ligands

摘要

Fluoride assisted stabilization of manganese(III) has been demonstrated by synthesizing new mixed-ligand fluoromanganate(III) complexes, A2[MnF4(L)] (A = K, L = citric acid, tartaric acid) from aqueous medium. Mixed-ligand fluoromanganate(III) complexes have been synthesized from a reaction of KMnO4, 40% HF with corresponding ancillary ligands maintaining KMnO4 : HF : ancillary ligand ratio as 1 : 4 : 1. Newly synthesized complexes are stable in absence of moisture and are practically insoluble in common organic solvents. Complexes were characterized on the basis of elemental analyses, chemical determination of oxidation state, FTIR, electronic spectral studies, room temperature magnetic moment measurements and by thermal studies. The room temperature magnetic moment values for the complexes lie in the range 4,9 to 5.1 μ_B. Electronic spectral studies suggests an appreciable splitting of ~5E_g ground state of manganesc(III) in the complexes leading to a distorted octahedral structure.