Atypical “Masked” Frustrated Lewis Pair Character in a Geminal‐Linked Phosphine‐Borane

The new fluorene-derived phosphine-borane [ⁱPr₂P(C₁₃H₈)BCy₂] (1) has been prepared. Unlike related geminal phosphine-boranes, 1 does not behave like a B/P frustrated Lewis pair (FLP), instead showing reactivity consistent with a “masked” FLP modulated by C(fluorene)-B bond scission. We exploit this behavior to perform P−Cl and N−H bond activation.

Abstract

We report the synthesis and reactivity of the geminal-linked fluorene-derived P/B frustrated Lewis pair (FLP) ⁱPr₂P(C₁₃H₈)BCy₂ (1). Compound 1 displays anomalous behavior towards small molecules, acting as a “masked” FLP. This behavior stems from significant polarization of the B−C(fluorene) bond in 1, as identified by density functional theory (DFT) computations. We exploit this B−C bond polarity through reactions with PhPCl₂, H₃N ⋅ BH₃, and ⁱPrNH₂, demonstrating P−Cl and N−H bond activation, respectively.

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