Experiment 4 Studying the Spectrochemical Series: Crystal Fields of ...

O
H 2N NH 2
O
H3C C CH3 H2 + H 2O 2 NH 3 + CO 2
O
H
O
O
H3C C CH3 H
O
O
H3C C CH3 H
Figure 3. Top: Hydrolysis of urea. Bottom: Deprotonation of acetylacetone forms the bidentate
ligand acetylacetonate (acac-). Systematic name is 2,4-pentanedionate.
Experimental Procedure
You will work in pairs in this lab to prepare two compounds: Cr(acac)3, and
[Cr(en)3]Cl3•2H2O. One of the pair will synthesize one compound, and the other partner will
prepare the other compound. The procedure for the syntheses for *both* compounds must be
written in your prelab. You will then share experimental and spectroscopic data (for all the
compounds, not just for the two that you prepare).
Another compound, [Cr(H2O)6](NO3)3•3H2O, will be provided to you; you will
spectroscopically analyze both this complex and your starting material, CrCl3•6H2O (this compound
is actually [CrCl2(H2O)4]Cl•2H2O]).
Finally, the electronic spectrum of [Cr(NH3)5Cl]Cl2, will be provided on the class web page
for your use in the Data Analysis section of your lab report.
How to Heat a Reaction with a Sand Bath/Magnetic Stirrer:
In this experiment, both syntheses require that you heat your reaction mixtures to boiling (or
to "reflux") in a sand bath placed on top of a magnetic stirring plate. Getting the reaction mixture to
stir well while heating can be problematic, so use the following procedure:
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