Reactions of the tertiary phosphines R₃P (R = Me, Bu, Oct, Cy, Ph) with 35% aqueous H₂O₂ gives the corresponding oxides as the H₂O₂ adducts R₃PO·(H₂O₂)_x (x = 0.5–1.0). Air oxidation leads to a mixture of products due to the insertion of oxygen into one or more P–C bonds. ³¹P NMR spectroscopy in solution and in the solid state, as well as IR spectroscopy reveal distinct features of the phosphine oxides as compared to their H₂O₂ adducts. The single crystal X-ray analyses of Bu₃PO and [Cy₃PO·(H₂O₂)]₂ show a PO stacking motif for the phosphine oxide and a cyclic structure, in which the six oxygen atoms exhibit a chair conformation for the dimeric H₂O₂ adduct. Different methods for the decomposition of the bound H₂O₂ and the removal of the ensuing strongly adsorbed H₂O are evaluated. Treating R₃PO·(H₂O₂)_x with molecular sieves destroys the bound H₂O₂ safely under mild conditions (room temperature, toluene) within one hour and quantitatively removes the adsorbed H₂O from the hygroscopic phosphine oxides within four hours. At 60 °C the entire decomposition/drying process is complete within one hour.

A new chelate phosphine linker and its Pd and Cu complexes have been synthesized and immobilized. The solvent impact on these immobilized species, their mobility, and coordination preferences have been studied in situ by HRMAS (High-Resolution Magic Angle Spinning) NMR. The catalyst recycling characteristics match the HRMAS results.

Five new safe, solid, and soluble H ₂ O ₂ adducts of triarylphosphine oxides, including the displayed ( p -Tol ₃ PO·H ₂ O ₂ ) ₂ , have been synthesized and characterized.