Organoantimony Dihydroperoxides: Synthesis, Crystal Structures, and Hydrogen Bonding Networks

Despite growing interest in the potential applications of p-block hydroperoxo complexes, the chemistry of inorganic hydroperoxides remains largely unexplored. For instance, single-crystal structures of antimony hydroperoxo complexes have not been reported to date. Herein, we present the synthesis of six triaryl and trialkylantimony dihydroperoxides [Me 3Sb(OOH) 2, Me 3Sb(OOH) 2·H 2O, Ph 3Sb(OOH) 2·0.75(C 4H 8O), Ph 3Sb(OOH) 2·2CH 3OH, pTol 3Sb(OOH) 2, pTol 3Sb(OOH) 2·2(C 4H 8O)], obtained by the reaction of the corresponding dibromide antimony(V) complexes with an excess of highly concentrated hydrogen peroxide in the presence of ammonia. The obtained compounds were characterized by single-crystal and powder X-ray diffraction, Fourier transform infrared and Raman spectroscopies, and thermal analysis. The crystal structures of all six compounds reveal hydrogen-bonded networks formed by hydroperoxo ligands. In addition to the previously reported double hydrogen bonding, new types of hydrogen-bonded motifs formed by hydroperoxo ligands were found, including infinite hydroperoxo chains. Solid-state density functional theory calculation of Me 3Sb(OOH) 2 revealed reasonably strong hydrogen bonding between OOH ligands with an energy of 35 kJ/mol. Additionally, the potential application of Ph 3Sb(OOH) 2·0.75(C 4H 8O) as a two-electron oxidant for the enantioselective epoxidation of olefins was investigated in comparison with Ph 3SiOOH, Ph 3PbOOH, t-BuOOH, and H 2O 2.