Fluoro-metallates : Syntheses, spectral characterization of new mixed-ligand fluoromanganate(III), manganate(II) and fluorozincate(II) complexes containing biogenic co-ligands

New mixed-ligand fluoro complexes of manganese(III), manganese(II) and zinc(II) containing biogenic co-ligands viz. aspartic acid, glutamic acid, proline, histidine or cysteine have been synthesized from aqueous medium from reaction of freshly prepared MnO(OH)/Mn(OH)(2) /Zn(OH)(2), 40% HF and the corresponding co-ligands, maintaining molar ratio of 1:4:1 at pH ca. 3-6 in presence of alkali metal carbonate, A(2)CO(3)/alkali metal hydroxide, AOH (A = Na, K or NH4). Complexes have been precipitated by addition of pre-cooled acetone/ethanol. The compounds are stable in solid state, however, fluoromanganate(iii) complexes undergo slow decomposition in aqueous solution. Compounds are practically insoluble in organic solvents such as methanol, ethanol, acetonitrile, dicholomethane and chloroform. The newly synthesized compounds have been comprehensively characterized by chemical analyses, chemical determination of oxidation state of manganese, magnetic susceptibility measurements, FTIR, electronic spectroscopic studies and by TGA/DTA studies.