Ligand design and self-recognition: a copper(II) complex that dimerizes via hydrogen bonds

The ligand ethylene-dianthranilate (1) can accommodate both tetrahedral and square-planar coordination geometries. When bound to Cu(II) and in the presence of an exogenous axial ligand, 1 adopts an equatorial binding mode. This coordination enforces a parallel geometry of the NH bonds and, by molecular self-recognition, predisposes the complex to dimerization by forming back-to-back hydrogen bonding interactions.