13C‐ und 1H‐NMR‐spektroskopische Untersuchungen an 2,9‐substituierten Fluorenen

Abstract

13C‐ and 1H‐NMR‐spectroscopical Investigations of 2,9‐substituted FluorenesThe 13C‐ and 1H‐chemical shifts for a series of 9‐substituted fluorenes and 9‐substituted 2‐nitrofluorenes, where the substituents are various azarenium ions, have been determined, shift data for several other fluorenyl compounds are also presented. The exact assignments of the 13C‐signals are possible by comparison of calculated shifts from 13C‐data with experimental 1H‐values. The substituent effects are discussed in terms of transmissions of electronic interactions. The substituent chemical shifts (SCS) for selective positions of the fluorene system give a linear correlation with the substituent constants σI, F, respectively. An increment model for the calculation of the empirical 13C‐chemical shifts of N‐(2‐nitrofluorene‐9‐yl)azareniumions 3b–6b are presented.