Self‐Assembly and Structure of Cobalt(II) Complexes Using Diaminodiamide Ligands

The self‐assembly of Co(II) with two diaminodiamide ligands, 4,7‐diazadecanediamide and 4,8‐diazaundecanediamide, gave two different crystals, [(C₈H₁₈N₄O₂)Co(OH)₂Co(C₈H₁₈N₄O₂)]Cl₂ ( 1 ) [Co(C₉H₂₀N₄O₂)(Cl)(H₂O)]·Cl·2H₂O ( 2 ). Structures of 1 and 2 were characterized by single‐crystal X‐ray diffraction analysis. Structural data for 1 shows a novel type of binuclear complex with distorted octahederal coordination geometry around the Co atoms through the hydroxo bridges. By using inter‐connector N‐H···N hydrogen bonding interactions as building forces, each cationic moiety [(C₈H₁₈N₄O₂)Co(OH)₂Co(C₈H₁₈N₄O₂)]²⁺ is linked to neighboring ones, producing a charged hydrogen‐bonded 1D chain‐like structure. The chains are further connected into a 2D layer in a (4,4)‐topology via N‐H···Cl_free hydrogen‐bonding interactions. Structural data for 2 indicate that the cobalt atom adopts a six‐coordinated N₂O₄ environment, giving a distorted octahedral geometry, where two N‐ and two O‐donor sets of ligand located at equatorial positions and one water and one chloride occupied at axial positions. Through NH···Cl‐Co and OH···Cl‐Co contacts, each cationic moiety [Co(C₉H₂₀N₄O₂)(Cl)(H₂O)]⁺ in 2 is linked to neighboring ones, producing a charged hydrogen‐bonded 1D chainlike structure. Thus, the crystal‐engineering approach has proved successful in the solid‐state packing due to steric strain effect of the diaminodiamide ligand.