Reaction of Rosenthal's Zirconacyclocumulenes with Chlorophosphines

The zirconacyclocumulenes 1a (R = CH3) and 1b (R = Ph) were prepared by isomerization
of bis(propynyl)ZrCp2 or bis(phenylethynyl)ZrCp2, respectively, catalyzed by B(C6F5)3 (6 mol
%). The compounds 1 added PCl3, PhPCl2, or Ph2PCl with cleavage of only one zirconium−carbon single bond. Chloride was added to zirconium and the remaining −PCl2, −P(Ph)Cl,
or −PPh2 moiety attached at the distal β-carbon atom of the strained ZrC4R2 metallacycle
to yield the respective ring-opened Zr/P-substituted enyne systems (5−7). The complexes
7a and 7b (both with −PPh2) and 6b (with −P(Ph)Cl) were characterized by X-ray diffraction.