Camphene-derived primary and hydroxymethyl phosphines

Abstract

Thermal disproportionation of (2,2-dimethylbicyclo[2.2.1]hept-3-ylmethyl)phosphinic acid (endo-8-camphanylphosphinic acid, camPO₂H₂) yields the primary phosphine (2,2-dimethylbicyclo[2.2.1]hept-3-ylmethyl)phosphine (camPH₂). The compound has been characterised by NMR spectroscopy, and as its tris(hydroxymethyl)phosphonium chloride salt [camP(CH₂OH)₃]Cl, synthesised by reaction with excess formaldehyde and hydrochloric acid. The X-ray crystal structure of this phosphonium salt is reported, confirming the endo position of the phosphonium group. On treatment with triethylamine base, camP(CH₂OH)₃ ⁺Cl⁻ is converted to the hydroxymethylphosphine camP(CH₂OH)₂. The sulfide and selenide of this phosphine have been prepared, together with the platinum(II) complex cis-[PtCl₂{camP(CH₂OH)₂}₂]. The gas-phase decomposition of camPH₂ has been investigated using the technique of IR laser powered homogeneous pyrolysis. Results indicate the initial elimination of phosphine, followed by the rearrangement and decomposition of camphene through two distinct pathways.