¹³C‐NMR‐spektroskopische Untersuchung einfach substituierter Flavyliumsalze

Abstract

13C‐N.M.R. Spektroscopical Studies on Simply Substituted Flavylium‐Salts On a series of differently substituted flavyliumsalts 1‐3 their 13C‐NMR‐chemical shifts and their 1J(13CH) coupling constants were recorded and compared with results received by means of semiempirical PPP calculations and using LFE relationships. Both the experimental and theoretical results exhibit concordantly a characteristic alternate electron distribution along the conjugated π‐system of the compounds studies and reveal the distinct influence of donor and acceptor substituents on the electron distribution in both the benzopyrylium and the aryl moiety of the flavylium salts studied.