SYNTHESIS NO.11

Bisethylenediaminecopper (II) Diiodocuprate (I)

1. Dissolve approximately5 g of well pulverized CuSO4 • 5H2O weighed to the nearest 0.01 g, in 20 ml distilled water in a 250 ml beaker.

2. Add about 3.5 ml anhydrous ethylenediamine, C2H4(NH2)2 to the solution prepared in step 1. Ethylenediamine stinks and is very hard on skin, therefore use under the hood ++ and take care! Mix thoroughly. This will produce the deep blue [Cu(C2H4(NH2)2)2] ion.

3. Dissolve 8.5 g BaI2 • 2H2O, weighed to the nearest 0.1 g, in 20 ml distilled water. Slowly and with swirling, add this solution to the one prepared in step 2.

4. With approximately 0.5 g Celite added to aid in the filtration, suction-filter off the precipitated BaSO4 using a large Büchner funnel and a clear filter flask. Wash the precipitate with two 5-ml portions of water, letting the washings combine with the filtrate. See the special sheets on recrystallization for proper washing techniques. Discard the precipitate and retain the filtrate in the filter flask.

5. Add 48 g KI, weighed to the nearest 0.1 g, to 60 ml distilled water in a 250 ml beaker. Heat to boiling on a hot plate to dissolve.

6. To the boiling solution prepared in step 5 add 7.6 g CuI weighed to the nearest 0.1 g. The CuI should be ground before dissolving it. Stir well in order to dissolve as much CuI as possible.

7. Since small quantities of black particles may be in the hot solution prepared in step 6 it must be suction-filtered directly into the solution retained in the filter flask in step 4.

8. Transfer the slurry of gray-brown product from the filter flask to a beaker, using a minimum amount of wash for rinsing.

9. Cool the solution from step 8 to 0ºC in an ice bath, then suction-filter off the product. Wash with two 10-ml portions of ice cold water, then with several portions of acetone to aid in drying. Use proper washing techniques. This filtration may be very slow. If it is, it may be appropriate to start preparing the second compound. Be especially careful when washing the precipitate. Be sure to use ice-cold water.

10. Dry the product in the air. It may be left in your desk over the week spread out on a watch glass, or dried for half an hour or so in the oven at 55ºC. Recrystallization is not possible because the product is insoluble in organic solvents and it decomposes in hot water.