Short, strong hydrogen bond between an aryloxide and phenol in aprotic media

Three examples of unsupported short, strong hydrogen bonds (SSHBs) between phenolic moieties in aprotic media are reported in three salts of the biphenoxide [{3,5-OC 6 (CF 3 ) 2 H 3 } 2 H] − anion, analogous to bifluoride, [FHF] − . The compounds were synthesized with three different cobalticinium cations and characterized via solution NMR and UV–Vis spectroscopies, elemental analyses, and single-crystal X-ray diffraction. These SSHB protons do not exchange with the aprotic solvent in solution or in the solid state and are important contributors to the study of SSHBs in enzyme active sites that often exclude water.