Triflate's bigger brother: The unprecedented tribrate anion, [Br₃CSO₃]⁻

Abstract

The synthesis of the unprecedented [Br3CSO3]− anion starts with the bromination of phenylmethanesulfonate, C6H5OSO2CH3, with KOBr leading to C6H5OSO2CBr3. The formation of the [CBr3] moiety has been proved, also by an X‐ray structure determination of the compound (triclinic, P‐1, a=685.9(2), b=698.1(2), c=1190.2(3) pm, α=93.99(1)°, β=97.42(1)°, γ=94.45(1)°). The ester C6H5OSO2CBr3 can be split under basic conditions. The resulting acid provides access to the yet unknown tribromomethanesulfates (“tribrates”). K[Br3CSO3] ⋅ H2O, the first tribrate known so far has been characterized comprehensively, including an X‐ray structure determination (monoclinic, C2/c, a=2267.1(2), b=1282.25(8), c=2618.2(2) pm, β=111.266(2)°), vibrational spectroscopy and theoretical calculations. Moreover, the thermal analysis shows that, after loss of the crystal water, the tribrate decomposes between 530 and 630 K.

The Molecular Structures of Lithium Trichlate, Li[Cl3CSO3]⋅2H2O, and Lithium Tribrate, Li[Br3CSO3]⋅2H2O

“…Also for K[Br 3 CSO 3 ] • H 2 O the CÀ S bond has been found to be shorter than observed for the trichlates known so far. [20] However, theoretical investigations of the dimers in Li[Cl S1). If the {Li 2 (X 3 CSO 3 ) 2/1 (H 2 O) 2/1 (H 2 O) 2/2 } dimers are treated as molecules 84 normal vibrations can be expected.…”

“…Aqueous tribric acid was yielded from phenylmethanesulfonate, which is first brominated by KOBr, then cleaved in alkali medium and lastly reacted with an ion exchange column. [20] X-ray determinations on single crystals of the compounds have been performed with a Bruker D8 VENTURE KAPPA diffractometer using MoK α radiation. The data were processed with the software of the diffractometer, [23][24][25] the structure determination and refinement was done with SHELX suite.…”

“…Subsequently, we presented the characterization of K-[B 3 CSO 3 ] • H 2 O, the first tribrate up to now. [20] By ion exchange the potassium salt can be converted to an aqueous solution of Br…”