THEORY:
GLASSWARE AND CHEMICALS REQUIRED:
RESULTS:
The bis (dimethylglyoxamato) nickel (II) complex i.e. [Ni(dmg)2] or [Ni(C4H7O2N2)2] is
prepared by the reaction of neutral or slightly acidic nickel ammonium sulphate
{NiSO4.(NH4)2SO4.6H2O} solution with alcoholic dimethyl glyoxime solution followed by the
addition a slight excess of ammonium hydroxide NH4OH. The general reaction of the formation
of [Ni(dmg)2] complex is shown as follow
GLASSWARE AND CHEMICALS REQUIRED:
Glassware and apparatus: Beaker, funnel, glass rod, sintered glass crucible or porcelain
filtering crucible, conical flask, Water bath Thermometer.
Reagents and Chemicals: Ammonium nickel sulphate {NiSO4.(NH4)2SO4.6H2O}, Alcoholic
dimthyl glyoxime (C4H7O2N2), Ammonium hydroxide NH4OH, Dilute HCl.
PROCEDURE:
Weigh out accurately 0.3-0.4g of pure nickel ammonium sulphate and dissolve it in 10 mL of
water. Add 5mL of dil. HCl in it and dilute the resulting solution to 200mL. Heat the solution to
70-80°C, add a slight excess (about 50 mL) of alcoholic dimethyl glyoxime reagent. Immediately
add dilute ammonia solution (NH4OH) dropwise with stirring until precipitation occurs, then add
15-20 drops excess of NH4OH solution to ensure the complete precipitation. Heat the solution on
water bath about 15-20 minutes and allow it to cool at laboratory temperature. Formation of red
coloured precipitate indicates the completion of the reaction. Allow the precipitate to stand for
15 minutes. Filter the precipitate through a pre-weighed sintered glass crucible or porcelain
filtering crucible. Wash the precipitate with cold water until free from chloride and dry it at 110-
120°C for about 30 min. Allow to cool in a desiccator, weigh and report the yield.
REACTIONS INVOLVED:
Following reactions are involved in the formation of bis (dimethylglyoxamato) nickel (II)
complex.
RESULTS:
(i) Physical state: Solid
(ii) Colour: Red
(iii) Yield: ……… g
STRUCTURE:
Two molecules of bidentate dimethyl glyoxime ligand are attached with Ni (II) in a square planar
geometry involving dsp2
hybridization. It is diamagnetic in nature. The coordination number of
Ni is 4. The structure of bis (dimethylglyoxamato) nickel (II) complex is shown as follow.
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