Reaction of the gray powder from the reduction of anhydrous PrCl/sub 3/ by K in tetrahydrofuran with cis,cis-1,5-cyclooctadiene yields a red-brown solid insoluble in tetrahydrofuran. The compound is unstable, decomposing slowly at room temperature in an inert atmosphere. However its oxidative extraction with benzene gave almost exclusively 1,3,5,7-cyclooctatetraene C/sub 8/H/sub 8/ and it reacts slowly with UCl/sub 4/ to form uranocene U(C/sub 8/H/sub 8/)/sub 2/. The infrared and NMR spectra match those reported for K/sub 2/C/sub 8/H/sub 8/. Several control reactions were conducted to define the role of Pr in this conversion. (JSR)