Photolysis of dicarbonyl(cyclopentadiene)rhodium complexes with a pendent alkyne unit

The syntheses of dicarbonyl[1-(5,5-dimethylhex-3-inyl)-3-phenylcyclopentadienyl]rhodium (7) and its congeners 8 and 9 are reported. Photolysis of 8 and 9 leads to a replacement of one CO ligand by the tethered alkyne unit, yielding 16, and to the dirhodium complexes 17 and 18. The structural assignment of 17 and 18 is based on X-ray studies. The photolysis of 9 leads to 19 and 20.