Polymorphic Forms of the Diaminopyrene-p-chloranil and Related Molecular Complexes

Abstract

I REPORTED earlier that most of the quinone complexes with electrical resistivities of 10⁶ ohm cm or less have essentially dative ground states¹. The only exceptions found were the 1,6-diaminopyrene complexes with p-chloranil and p-bromanil. It therefore seemed worthwhile to examine these complexes further. The resistivity values reported for the p-chloranil complex are scattered in a wide range, namely 10³–10⁴ ohm cm for the pressed polycrystalline samples^2,3 and 10⁵–10⁹ ohm cm in the three directions of the single crystal⁴. This communication reports the existence of some polymorphic forms of the 1,6-diaminopyrene-p-chloranil and related molecular complexes. The polymorphic forms are distinctly different in colour, diffuse reflectance spectrum, vibrational spectrum, X-ray diffraction, and also electrical resistivity. The scattered resistivity values appear to be well related to those of such forms.