We have found and reported catalytic cycles containing a Zr(II) species and zirconacycles in carbon–carbon bond formation by the reaction of olefins and/or acetylenes with Grignard reagents. 1–5 One principle of the Zr(II)-mediated or -catalyzed reactions is the use of facile interchange of its oxidation states, II and IV. The zirconium(II) species is known to be of good π-electron accepting ability and oxidatively couples two unsaturated organic molecules. During the coupling ...
