NMR and X-ray analyses of triethyl 3,7,11-triphenylcyclonona[1,2-b;4,5-b′;7,8-b″]tripyrrole-2,6,10-tricarboxylate: reinvestigation of crown vs saddle conformation of cyclononatripyrroles

From X-ray analyses of 3,7,11-triphenylcyclonona[1,2-b;4,5-b′;7,8-b″]tripyrrole-2,6,10-tricarboxylate (CNTP ), the molecules existed as saddle forms in both crystals of ·3ClPh and ·1/2CHCl3. In the former crystal, hydrogen bonds between pyrrolic hydrogen and ester carbonyl oxygen spread two-dimensionally, forming molecular sheets, between which the solvent molecules were included, while two independent molecules were bounded three-dimensionally by the hydrogen bonds in the latter. In CDCl3, CNTP was observed to adopt a crown form, while interconversion of the conformers was observed in C5D5N.