Related Experiment Video
Updated: May 24, 2026

Solution-Processed, Surface-Engineered, Polycrystalline CdSe-SnSe Exhibiting Low Thermal Conductivity
Published on: May 17, 2024
The ring-chain tautomeric equilibria of selenium macrocyclic compounds: the isolation of the ring tautomer
Monica Bucşa1, Alpár Pollnitz, Richard A Varga
1Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, 11 Arany Janos Str., 400056 Cluj-Napoca, Cluj, Romania.
Abstract:
A broadening of the investigation of the ring-chain tautomeric process of N-substituted 1,3-X,N-heterocycles (X = O, S, NR) to Se containing macrocyclic compounds allowed the isolation and structurally solid state characterization of the cyclic tautomer 7, which due to the length of the aliphatic chain, is able to form a stable six-membered ring (6-endo-trig). The theoretical calculations based on the DFT method (Gaussian 03 software package) also support the fact that tautomer 7 is more stable than the chain tautomer 6. Thus, based on the ring-chain tautomerism of the macrocycles that contain alkyl chains with amino-imino, imino-alcohol or sulphur-imino groups, combined with a strategy that allows the formation of a stable six-membered ring, the main reaction products will be the cyclic tautomers. The ring-chain equilibria of these macrocycles could be exploited advantageously in different areas of macrocyclic, physical and medicinal chemistry in order to obtain compounds with practical applications.
Related Concept Videos
Stereoisomerism of Cyclic Compounds
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Chirality at Nitrogen, Phosphorus, and Sulfur
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...

