A wide range of carbenoids (1-lithio-1-halo species), including those with α-SiR3, OEt, SPh, SO2Ph, P (O)(OEt) 2, and CN substituents, insert into 5-member zirconacycles (saturated and unsaturated, mono-and bi-cyclic) to afford functionalized 6-member zirconacycles. 1- Lithio-1-haloalkenes insert to afford 6-member zirconacycles with an alkylidene substituent next to the metal. Unexpected double insertion of some carbenoids, and evidence for ...