The structure and intramolecular mobility of some derivatives bis(thio)phosphorylated amides in CCl4, CD2Cl2, CD3CN solutions were examined by 1H 31P NMR spectroscopy. A comparative analysis the temperature-dependent spectra studied compounds with symmetric asymmetric substitution at phosphorus atoms was carried out. Various processes identified – rotation around C-N bonds, conformational trans...

The molecular structures of sulphonamides are interesting for evaluating their mobility in soils and preparing composite complexes optimizing the use these drugs. In this work, several arylsulfonamides along with conformational analysis tautomerism were investigated theoretically. spectroscopical properties arylsulfonamides, also studied at level by using a computational modeling quantum mechan...

Equilibrium constants for keto-enol tautomerisation and migration of hydrogen from carbon to nitrogen to form enamine or zwitterion tautomers have been measured for 2-, 3and 4phenacylpyridines (PyCH,COPh) in aqueous solution at 25 "C. Relative tautomeric stabilities fall in the order ketoimine > enamine > enol and (for the 3-isomer) enol > zwitterion. Values of pKT, (-log KT) where KT = [enamin...

In this issue Yvonne Martin provides us with a ‘‘Perspective’’ addressing an important and too often overlooked problem in chemistry, biology, and drug discovery, tautomerism. As she notes, the extent of this issue goes beyond common expectations. The phenomenon shines a bright light on the limitations of our methods of chemical structure representation and data basing. The problem is multifold...

Abstract The energy profiles for ring opening of representative type B mesoionic 2,3-diphenyl-1,2,3,4-tetrazolium-5-olates, -thiolates, -aminides and –methylides alternative recyclisation pathways are investigated using ab initio MP2 calculations. energetics initial found to be comparable all systems, but the tetrazolium-5-olates anomalous in that no reaction pathway is accessible. influence so...