Molecular and crystal structures of dibenzenehemiporphyrazine complexes with dimethylformamide

The crystal structures of the 1: 1 and 1: 2 complexes between dibenzenehemiporphyrazine (I) and dimethylformamide (compounds II and III, respectively) are determined by X-ray diffraction. In both compounds, the macrocycle has a saddlelike shape. In III, the conformation of the macrocycle approximates the C _2v symmetry, which agrees closely with the results of quantum-chemical calculations for isolated molecule I and complex II. The ring conformation in crystal II is distorted under the effect of intermolecular interactions, as is evidenced by short intermolecular contacts. The complexes are stabilized by intermolecular N-H?O and C-H?O hydrogen bonds between the hydrogen atoms situated inside the cavity of the macrocycle and the oxygen atoms of the dimethylformamide molecules.