Frustrated Lewis Pair vs Metal–Carbon σ‑Bond Insertion Chemistry at an o‑Phenylene-Bridged Cp₂Zr⁺/PPh₂ System

Methyl anion abstraction from (o-diphenylphosphino)­phenyl­(methyl)­zirconocene by trityl tetrakis­(pentafluorophenyl)­borate gives the o-phenylene-bridged Zr⁺/P system 10. It behaves toward a variety of reagents as a typical Zr⁺/P frustrated Lewis pair (FLP). It undergoes cooperative 1,4-addition reactions to some chalcone derivatives and adds in a 1,2-fashion to a variety of organic carbonyls and to several heterocumulenes. The reactive Zr–C σ bond of the FLP 10 remains intact in these reactions. Complex 10 splits dihydrogen, but subsequently the Zr–C σ bond is protonolytically cleaved in this case. Only a few special reagents, among them carbon monoxide, undergo the usual insertion reaction into the Zr–C­(aryl) σ-bond of the Zr⁺/P system 10.