Metal Acetylacetonate Synthesis

1582 Words7 Pages
Experiment 1 : Synthesis of Metal Acetylacetonates Objective : To prepare tris(acetylacetonates)manganese(iii), Mn(acac)3 [Also called tris(2,4-pentanedionaye)manganese(iii)] Introduction : A general method of synthesis is to treat a metal salt with acetylacetone, acacH. Mz+ + z (acacH) M(acac)z + z H+ Complexes consist of a central metal atom surrounded by various other atoms or small molecules called ligands. It is important to recognize the nature of the ligand – the availability for coordination sites or ligating and the conditions under which these are available for coordination. Complexes can be positively charged, neutral or negatively charged. The overall charge on the complex is depends on the oxidation state of the metal…show more content…
Long duration of heating will loosen the bond between central atom and ligands. Characteristic of acetone is to increase the formation of complex. There is error in the acetone provided thus causing the adding steps of acetone to dissolve all the complex formed in the experiment. Sodium acetate trihydrate, as a base in this experiment, causing acetylacetone to lose a proton to form acetylacetone anion, acac-. Manganese has wide range of oxidation state from +7 to -1, however, in aqueous solution, manganese with +2 oxidation state is most stable and common. Mn2+ can be easily oxidized to form Mn(acac)3 in the presence of acetylacetonate ions as the bidentate ligands are packed around manganese ion. Potassium permanganate solution acts as oxidizing agent to oxidize Mn2+ to Mn3+, as reaction equation shown below: MnO4- + 4Mn2+ + 8H+  5Mn3+ +4H2O The oxidized Mn3+ is then reacted with 3 acetylactonate ions to produce Mn(acac)3. the purpose of second time adding sodium acetate solution is to neutralize acid produced during the deprotonation of acetylacetone which donated H+, as reaction equation shown
Open Document