Analyse kernmagnetischer Resonanzspektren vom Typ A2B2 mit Ergebnissen von para-disubstituierten Benzolen, Äthylengruppen und Pyrrol

Abstract

The analysis of A₂B₂ spectra, especially the assignment of lines is further treated. Explicit expressions for the A₄ spectrum as a limiting case of an A₂B₂ spectrum have been calculated and are listed. The observation of multiple quantum transitions in an A₂B₂ system is reported. Spin coupling and shielding parameters are given for 30 para-disubstituted benzenes and some other compounds. For pyrrole an improved set of spin coupling parameters could be obtained, making use of the information from C¹³ satellites. Substituent effects for the meta spin coupling in paradisubstituted benzenes are derived. A correlation with the electronegativity of the substituent is demonstrated and some arguments for a theoretical treatment are discussed.