Synthesis, Structure, and Supramolecular Chemistry of Three Azide Manganese Complexes with 2, 6-Bis(benzimidazol-2-yl)pyridine

Three azide complexes with the tridentate ligand 2, 6-bis(benzimidazol-2-yl)pyridine (H2BBIP) were synthesized and their complicated supramolecular interactions were investigated with single-crystal X-ray diffraction. Interestingly, the complexes are assembled by bifurcated hydrogen bonding, double helical pp stacking, or anionp stacking interactions of the benzimidazole rings by tuning the reaction conditions (temperature, ratio, solvent). Complex 1 is a mononuclear compound, namely, Mn(H2BBIP)N3(CH3O).CH3OH. In its 3D supramolecular network, the nitrogen atom of the azide anion is acting as hydrogen bonding bifurcated acceptor. Complex 2 is a dinuclear compound, namely, Mn2(H2BBIP)2(N3)2.(H2O)0.5. The dinuclear unit is connected by intramolecular pp stacking interactions. Furthermore, double helical pp stacking interactions in the benzimidazole rings are observed. Complex 3, Mn2(H2BBIP)2(N3)2.CH3OH, can be formulated as a pseudopolymorph of complex 2, which exhibits intramolecular pp stacking interactions as well as anionp interactions in the dinuclear unit.