Synthesis and Characterization of a Zinc(II) Complex of Bispicen

The synthesis of a Zn(II) complex of bispicen, the tetradentate ligand N,N′-bis(2-pyridylmethyl)-ethylenediamine, of composition [Zn(bispicen)Cl(H₂O)]₂[ZnCl₄] is reported. Its crystal and molecular structure was determined by single-crystal X-ray diffraction methods. It crystallizes in the monoclinic space group C2/c with Z = 4 molecules per unit cell. The Zn(II) cation in the [Zn(bispicen)Cl(H₂O)]⁺ complex is in a distorted octahedral environment, coordinated to a neutral bispicen molecule acting as a tetradentate ligand through its two amine nitrogen atoms, at cis positions, and its two pyridyl N atoms, at trans positions. The six-fold coordination is completed by a chloride ion and a water molecule. The tetrahedral [ZnCl₄]²⁻ counter-ion lies on a crystallographic twofold axis. The complex was further characterized by FTIR spectroscopy, and its vibrational behavior compared with that of the dihydrated tetrahydrochloride of free bispicen.