Polysulfonylamines, CXII - A novel solid-state aspect of 2-pyridones: Isolation and x-ray structures of bis(2-pyridone)hydrogen(I) and bis(6-methyl-2-pyridone)hydrogen(I) dimesylamides

The compounds (2-pyridone)(2)H+(MeSO2)(2)N- (1, monoclinic, space group P2(1)/n) and (6-methyl-2-pyridone)(2)H+(MeSO2)(2)N- (2, triclinic, P1) crystallize selectively and in good yields when the parent 2-pyridones (2-hydroxypyridines) are treated with the strong NH acid dimesylamine in acetonitrile or acetone. The corresponding 2-hydroxypyridinium salts could not be obtained. In the unprecedented crystal structures of 1 and 2, two pyridone units are linked by a proton to form very short and approximately symmetric O ... H+... O hydrogen bonds, the adjacent C-O distances being appreciably elongated as compared to "free" pyridones [1: O ... O 241.8(2), C-O 127.8(3) and 129.1(2) pm; 2: O ... O 243.8(2), C-O 128.1(2) and 129.2(2) pm]. In both crystal packings, the homoconjugate cations and the dimesylamide anions are alternately associated into chains by an N-H ... N- and an N-H ... O hydrogen bond.