H-1, C-13 AND N-15 NUCLEAR-MAGNETIC-RESONANCE STUDIES OF POLYAMIDINESPREPARED FROM DI(4,4'-AMINOPHENYL) METHANE AND DIFFERENT TRIETHYL ORTHOESTERS-POLYMERS WITH A PROTOTROPIC TAUTOMERISM

N-1,N-2-disubstituted polyform-, acet- and -benzamidines containing th e 4,4'-substituted diphenyl methane unit were studied by means of H-1, C-13 and N-15 nuclear magnetic resonance (n.m.r.) in solution. The n. m.r. signals were assigned. For the polyacet- and -benzamidine slow ta utomerism on the n.m.r. time scale resulted in separate signals for th e amino and imino moiety due to preference for the E-anti configuratio n of the amidine group. This tautomerism was much faster for the polyf ormamidine due to cyclic dimerization of formamidine groups in the pre ferred E-syn configuration. In this case, the signals of the amino and imino moiety coalesced. (C) 1997 Elsevier Science Ltd.