Structural and IR-Spectroscopic Characterization of Aqua Lithium Acesulfamate, an Outlier of the M(ace), M: Na⁺, K⁺, Rb⁺, Cs⁺, Isomorphic Series

Abstract

The crystal structure of aqua lithium 6-methyl-1,2,3,-oxathiazine-4(3H)-one, 2.2-dioxide, for short Li(ace)H₂O, was determined by X-ray diffraction methods. It crystallizes in the triclinic P1¯ space group with a = 6.1750(9) Å, b = 7.3969(9) Å, c = 9.016(1) Å, α = 105.88(1)°, β = 94.59(1)°, γ = 97.80(1)°, and Z = 2 molecules per unit cell. The crystal structure of Li(ace)H₂O sharply departs from the other heavier alkaline-metal acesulfamates, namely the monoclinic isotypic M-ace (M from Na⁺ to Cs⁺) family of salts. Lithium is in a distorted LiO₄ tetrahedral coordination with acesulfamate carbonyl, sulfoxide and water oxygen atoms. The FTIR spectrum of the new compound was also recorded and is briefly discussed. Some comparisons with other simple acesulfamate salts are also made.