The alkali metal salts of methyl xanthic acid

Abstract

Methyl xanthates of the type M(SSC-OMe) (M = Li–Cs) are readily formed when carbon disulfide is reacted withthe corresponding alkali metal hydroxides in methanol exposedto air, or with the alkali metal methoxides in dry methanol orTHF under exclusion of air. The reactions are easily monitoredby13C NMR spectroscopy. The Na, K, Rb, and Cs salt could beisolated in high yields, while the Li salt decomposed upon at-tempted isolation. All compounds are readily complexed by crown ethers and form isolable 1:1 adducts, including the elusive Li salt. All products were studied by NMR (1H, 13C, and alkali metal nuclei) and IR spectroscopy, and most of them where structurally characterized by single-crystal X-ray diffraction. Li(SSC-OMe)(12c4) (12c4 = [12]crown-4) and Cs(SSC-OMe)(18c6) (18c6 = [18]crown-6) represent the first structurally characterized lithium and caesium xanthate complexes, respectively.