An Unorthodox Conformation of [18]porphyrin-(1.1.1.1) Heteroanalogue—21,23-Ditelluraporphyrin with a Flipped Tellurophene Ring Financial support from the State Committee for Scientific Research KBN of Poland (Grant: 3 T09A 155 15) and the Foundation for Polish Science is gratefully acknowledged.

Abstract

The flexible partially inverted structure of an 18-π-electron porphyrin-(1.1.1.1)-like framework is found for 21,23-ditelluraporphyrin (see structure). The dihedral angle between the plane of meso-carbon atoms and the inverted tellurophene plane in the solid state is 123.0(2)°, while in solution the porphyrin molecule interchanges between two energetically identical flipped forms.