Iridium complexes cyclo-octa-1,5-diene

No complex was obtained on treatment of iridium (III) chloride with ethylene (67, 97, 138) or cyclo-octa-1,5-diene (45), but the ethylene complex [IrCl2(C2H4)] was reported to be formed by the action of ethanol on iridium chloride (67,138). No further examination of this complex has been reported. 

Note added in proof In the preparation of rhodium and iridium complexes from cyclo-octa-1,5-diene, however, all the uncomplexed olefin is converted to the 1,3-diene. The same isomerization is catalyzed by tertiary phosphine complexes of rhodium and iridium, and the 1,4-diene can be detected as an intermediate (117a). 

The complex bis(cyclo-octa-l, 5-diene)iridiumtrichlorotin, of previously uncertain constitution, is found to contain the SnCl group linked through tin to the iridium atom. The distance Ir-Sn, 2,73 A (at a stage of refinement R s 12,9%), is fairly close to a value derived from normal radii applicable to compounds not containing metal-metal bonds. 

A number of metal complexes of cyclo-octa-1,5-diene are reported from cobalt, palladium, rhodium, iridium, and copper(i) systems. Bis(cyclo-octa-l,5-diene)nickel has been used to couple alkenyl halides. An X-ray study of (356), obtained by proton abstraction from tricarbonylcyclo-octa-l,5-diene-... 

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