Spectral Study of the Hydration Isomers

For Cr , can be directly calculated from the longest wavelength spin-allowed d-d band. Hence the absorption spectra of the hydration isomers can be used to test the law of average environment. Because of the possibility of equilibria in solution, it is more useful to obtain spectra of the solids as in (Sec.2.4.1). Spectra of [CrCy will be important especially since water and chloride are not far apart in the spectrochemical series. This large anion can be precipitated by a large cation eg [Co(pn)3] 

4 g C1CI3.6H2O (the green unpurified salt) with 50 cm cone. HCl to dissolve the salt. Add to the solution of 3.8 g of [Co(pn)3] Br3 (Sec.14.10.1) with shaking and allow to stand to induce crystallisation. Collect the crystals by filtration under vacuum, wash with small volumes of water then ethanol and finally ether. Suck dry and then finish drying in an oven at 105 C. Weigh your product and calculate the percentage yield. 

Using all the spectral data, check the applicability of the law of average environment. Comment on any features of interest in the recorded spectra. 

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