In general, if the atoms that make up the ring contain heteroatoms, such rings become heterocycles, and organic compounds containing heterocycles are called heterocyclic compounds. An article called The structural systematics of protonation of some important nitrogen-base ligands. III. Some (univalent) anion salts of some hindered unidentate nitrogen bases, published in 2006, which mentions a compound: 530-66-5, Name is quinoliniumhydrogensulphate, Molecular C9H9NO4S, COA of Formula: C9H9NO4S.
Recent structural studies of salts of the 2,2,6,6-tetramethylpiperidinium cation [tmpH]+ (chloride, bromide; thiocyanate) present as interesting dimeric or polymeric associations linked by pairs of directional H-bonds from the cationic = NH+2 moieties to ‘two-coordinate’ anions. Present single crystal x-ray studies have characterized the iodide, perchlorate, nitrate and trifluoroacetate complexes, all, like those of the preceding studies, [tmpH]+X- (anhydrous). A variety of forms are found: the nitrate compound is dimeric [[tmpH](O·NO·O)2[Htmp]], the trifluoroacetate compound being similar in form while the iodide and perchlorate salts are mixtures of dimers (with the anions essentially single atom bridges) and single-stranded helical polymers, the stoichiometric ratio of these being 1:1 and 2:1 in terms of [tmpH]X formula units, resp. A study of 4-keto-2,2,6,6-tetramethylpiperidinium thiocyanate shows it to be a dimer [[OtmpH](SCNNSC)[HtmpO]], unlike its previously studied chloride analog which is a cyclic tetramer. A new P21/n phase of diisopropylammonium chloride, derivative of the previously described P212121 and P21 forms, is reported, together with descriptions of protonated salts of the other hindered unidentate bases 2,6-lutidine (as the chloride salt), quinoline (as the perchlorate, trifluoroacetate, hexachlorostannate and bisulfate salts) and 2-quinaldine (as the chloride (anhydrous and monohydrate) and hexachlorostannate salts), all displaying arrays derivative of ion-pair formation (extended by anion-anion H-bonds as well in the bisulfate salt) and, in the case of the aromatic bases, dominated by parallel stacking.
In addition to the literature in the link below, there is a lot of literature about this compound(quinoliniumhydrogensulphate)COA of Formula: C9H9NO4S, illustrating the importance and wide applicability of this compound(530-66-5).
Reference:
Thiazolidine – Wikipedia,
Thiazolidine – ScienceDirect.com