Coordination Compounds of Manganese

Electrodeposition and Characterization of Manganese Coatings

“…Various reports indicate different values of this transition current density, which might be due to the different deposition conditions employed. For aqueous electrolytes containing MnSO 4 and (NH 4 ) 2 SO 4 , Mn 2ϩ can exist in the forms ͓Mn( [20][21][22] Due to the presence of the highspin 3d 5 manganese͑II͒ ion, all these compounds are octahedrally coordinated and possess zero ligand field stabilization energy. 20 Therefore, the complexes formed in this system are unstable.…”

“…From pH 2 to 4, Mn 2ϩ exists predominantly as ͓Mn(H 2 O) 6 ͔ 2ϩ , and at pH 4 to 6 as ͓Mn(H 2 O) 6Ϫn (NH 3 ) n ͔ 2ϩ , n increasing with pH. [20][21][22] Above pH 6.5, in the presence of air, the bulk electrolyte becomes gradually unstable due to the precipitation of manganese hydroxide ͓Mn͑OH͒ 2 ͔. Its oxidation product MnO͑OH͒ 2 also makes the solution unclear and lowers current efficiency, which is detrimental to manganese deposition.…”

“…1b. 21,24 The grains formed at low pH are separated by sharply contrasted boundaries, while inside each grain, a lamellar structure oriented along a specific direction is observed ͑Fig. 6, pH 2.1͒.…”