Unusual O-coordination of caffeine in tetrakis(μ-3,5-dinitrobenzoato- k2O:O′)bis[(caffeine-kO)copper(II)]

Article abstract of DOI:10.1107/S0108270106025467

The title compound (systematic name: tetrakis(μ-3,5-dinitro-benzoato- k²O:O′)bis[(3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione- kO²)copper(II)]}, [Cu₂(C₇H₃N ₂O₆)₄(C₈H₁₀N ₄O₂)₂], consists of paddle-wheel dimeric tetrakis(μ-3,5-dinitro-benzoato-k²O:O′)dicopper(II) units with O-coordinated caffeine molecules in both apical positions. The entire dimeric molecule lies on a tetragonal inversion 4 axis, and thus one nitrobenzoate anion with one Cu atom in a special position belong to the independent part of the molecule. The caffeine ligand bonded to the Cu atom is disordered on a local twofold non-crystallographic axis coincident with the 4 axis. A π-π stacking interaction is observed between the caffeine rings and adjacent symmetry-related benzene rings of the 3,5-dinitro-benzoate anions.