Zirconium complexes phosphine oxides

Cationic P compounds exhibit several modes of reactivity, including coordination to Lewis acids oxidation by acids, water, and alkyl chlorides and substitution of the stabilizing phosphine ligands by stronger donors (Scheme 17). Some of these P and As cations have also been shown to be useful sources of P and As ions that provide zirconium complexes (12) containing unique square-planar Pn environments (equation 22). ... 

In these and related reactions, the ether and alcohol ligands dissociate readily. The coordinated THF dissociates from the zirconium methyl complex to allow olefin polymerization, albeit more slowly than in the absence of THF. The ether dissociates from palladium and nickel to allow olefin to bind to the cationic palladium and nickel species, and alcohol and water are easily displaced from related Pt(II) complexesby hydrocarbons prior to C-H activation processes. Likewise, the THF and phosphine oxide ligands reversibly dissociate from the zirconium knido complex (Equation 2.18) prior to [2+2] additions with alkynes. - ... 

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