PubMed:20458386 JSONTXT

The [2+2] cycloaddition of alkynes at a Ru-P pi-bond. The Ru[double bond, length as m-dash]P double bond in the 5-coordinate terminal phosphido complex [Ru(eta(5)-indenyl)(PR(2))(PPh(3))] undergoes regioselective [2+2] cycloaddition with simple and activated alkynes to give metallaphosphacyclobutene complexes. These unusual examples of alkyne insertion into a metal-heteroatom bond represent potentially important intermediates in stereoselective routes to new phosphine reagents and ligands.