π-Expansion of 2,3,6,7-Tetraazanaphthalene with Two Embedded Heptagons: Highly Twisted Structure and Lone-Pair/π* Interaction in the Crystal

Synthesis and characterization of doubly diphenylene-fused 2,3,6,7-tetraazanaphthalene 1 are described. Single-crystal X-ray diffraction analysis showed the highly twisted structure of 1 with a degree of twisting of 13.0 degrees/angstrom, which is one of the largest values for a pi-system. In the crystal, molecules of 1 formed an orthogonal one-dimensional column with pi-stacking of diphenylene moieties and a short intermolecular C center dot center dot center dot N distance due to lone-pair/pi* interaction, which is a rare example of lone-pair/pi* interaction in a supramolecular assembly.

Automated summary

This article describes the synthesis and characterization of doubly diphenylene-fused 2,3,6,7-tetraazanaphthalene 1. X-ray diffraction analysis showed a highly twisted structure of 1, with a large degree of twisting. In the crystal, the molecules of 1 formed an orthogonal one-dimensional column with pi-stacking of diphenylene moieties and exhibited a rare example of lone-pair/pi* interaction in a supramolecular assembly.