Ammonium salts of benzoic acid and the crystal structure of ammonium hydrogen bisbenzoate

The ir spectrum of the isotopically isolated NH 3 D + ion was used to deduce the possible site symmetries of the NH 4 + ion in ammonium benzoate, NH 4 PhCOO, and ammonium hydrogen bisbenzoate, NH 4 H(PhCOO) 2 . The NH 4 + ion in both crystals is strongly hydrogen-bonded, one of the two isotopically isolated ND frequencies in ammonium benzoate being the lowest such frequency reported to date. The site symmetry C 2 of NH 4 + in NH 4 H(PhCOO) 2 has been confirmed by determining the crystal structure of this compound. The bond in the dibenzoate ion, is short, 2.46(1) Å, and probably symmetric.