Cliff Kubiak

Clifford P. Kubiak

Preparation of Chloro-1,5-cyclooctadiene Metal(I) Dimer

[MCl(COD)]2 M=Rh,Ir and [RhCl(cod)]2

2MCl3 + 2C8H12 + 2CH3CH2OH → [MCl(C8H12)]2 + 4HCl + 2CH3CHO


Into a 100 mL 3-necked flask equipped with a condenser, a magnetic stir bar, and a heating mantle is added 2.0 g of MCl3.3H2O. The system is flushed with N2 gas and 25 mL of degassed H2O added. It is then heated under N2 while stirring until all the solids are dissolved. Degassed, freshly opened EtOH, 30 mL, is added by a syringe and the mixture is stirred for 3 min. 1,5-Cyclooctadiene (COD), 2 mL, is added to the flask by a syringe and the solution is refluxed under N2 for a period of 18 h - 24 h. The temperature is slowly cooled while a stream of N2 is passed through the solution to decrease the volume of solvent to about 30 mL. The solid is collected by filtration and is washed with water 3 times and dried under vacuum. The solid is brick-red for M=Ir and yellow for M=Rh.

Typical yield is 1.5 g (78%).


For M=Rh, the ratio of 5:1 EtOH/H2O works well.


1. Herde, J. L.; Lambert, J. C.; Senoff, C. V. Inorg. Synth. 1974, 15, 18. (M=Ir)

2. Giordano, G.; Crabtree, R. H. Inorg. Synth., 1990, 28, 88. (M=Rh)