Brominated Methanesulfonates: Characterization of K[Br₃CSO₃] ⋅ H₂O, K₂[Br₂C(SO₃)₂] ⋅ H₂O and K₃[BrC(SO₃)₃] ⋅ H₂O

Bromination of phenyl methanesulfonate, C₆H₅OSO₂CH₃, with KOBr followed by hydrolytic cleavage of the phenyl ester leads to the tribromomethanesulfonate ("tribrate") K[Br₃CSO₃] ⋅ H₂O, which crystallizes in a hitherto unknown triclinic modification (P $\stackrel{-}{1}$ , a = 662.87(4) pm, b = 1090.98(7) pm, c = 1273.98(8) pm, α = 106.079(2)°, β = 93.438(2)°, γ = 90.121(2)°). In contrast to the synthesis of the tribrate, in which an aromatic ring must be present at the SO₃ group for a successful bromination, the synthesis of K₂[Br₂C(SO₃)₂] ⋅ H₂O (monoclinic, P2₁/c, Z = 4, a = 717.17(3) pm, b = 710.78(3) pm, c = 2092.50(9) pm, β = 94.732(2)°) and K₃[BrC(SO₃)₃] ⋅ H₂O (tetragonal, P4₃, Z = 4, a = 713.6(1) pm, c = 2324.50(7) pm) using KOBr do not need the phenylesters as starting materials. Comparing the CS bond lengths of the different anions with each other, a trend emerges in which the CS bond length increases with increasing number of SO₃ groups (decreasing number of Br atoms). Furthermore, an increase in thermal stability by ≈50 °C per additional SO₃ group can be observed. The compounds are characterized by X-ray diffraction, vibrational spectroscopy, and thermal analyses.