Reactions of (Diphenylphosphinomethyl)zirconocene Chloride with B(C6F5)3: Competition between P/B and P/Zr+ Frustrated Lewis Pair Reactions

The title complex Cp2ZrCl(CH2PPh2) reacts with B(C6F5)(3) under specific conditions by phosphinomethyl transfer to give the phosphane-stabilized salt [Cp2ZrCl+]-[Ph2PCH2B(C6F5)(3)(-)]. X-ray crystal structure analysis showed the P-Zr coordination. This salt is trapped by phenyl isocyanate in an in situ three-component reaction to yield the respective P/Zr+ frustrated Lewis pair (FLP) addition product. In contrast, a mixture of Cp2ZrCl(CH2PPh2)/B(C6F5)(3) and benzaldehyde under similar conditions gives the P/B FLP addition product. The Cp2ZrCl(CH2PPh2)/B(C6F5)(3) system may form a P/B adduct [Cp2ZrCl(CH2PPh2)center dot B(C6F5)(3)] or a P/Zr+ adduct [Cp2ZrCl center dot PPh2CH2B(C6F5)(3)]. From the former it seems to show P/B FLP reaction and from the latter P/Zr+ FLP behavior; the outcome is dependent on the specific reagent and reaction conditions chosen.