Ph₃AsO as a Strong Hydrogen-Bond Acceptor in Cocrystals with Hydrogen Peroxide and gem-Dihydroperoxides

Hydrogen-bonded cocrystals have attracted considerable attention as they allow fine-tuning of properties through the choice of hydrogen-bond donors and acceptors. In this study, triphenylarsine oxide (Ph₃AsO) is introduced as a strong hydrogen-bond acceptor molecule. Due to its higher Lewis basicity compared to triphenylphosphine oxide (Ph₃PO), it acts as a strong hydrogen-bond acceptor, which is demonstrated in six new cocrystals with H₂O₂ and gem-di(hydroperoxy)cycloalkanes. All cocrystals formed large, high-quality single crystals, which were analyzed by X-ray diffraction and IR spectroscopy. The cocrystal of Ph₃AsO with H₂O₂ shows prolonged stability without loss of oxidative power. In addition, the newly formed interactions were also present in solution and were detected by NMR spectroscopy. The higher electron-donating ability of Ph₃AsO compared to Ph₃PO was confirmed by competition experiments. Ph₃AsO exclusively binds H₂O₂, even in dilute aqueous solutions and in the presence of Ph₃PO. This study expands the range of hydrogen-bond acceptors and demonstrates that Ph₃AsO is a useful cocrystallizing tool in crystal engineering and a sensitive marker for hydrogen peroxide.