Sheets of Tetranuclear Ni(II) [2 × 2] Square Grids Structure with Infinite Orthogonal Two-Dimensional Water–Chlorine Chains

The tetranuclear nickel(II) complex [Ni-4(HL)(4)]Cl-4 center dot 4H(2)O {H2L = 1,5-bis[1-(pyridin-2-y)ethylidene]carbono hydrazone} has been prepared by reaction in methanol of nickel(II) chloride and H2L in 2:1, M:L molar ratio. The single crystal X-ray diffraction analysis revealed a 2 x 2 square grid of tetramer units with the metal ions joined in pairs by the alkoxide oxygen atom in the mu(2) mode with octahedral geometry around each nickel ion. The supramolecular structure shows that the tetramer units are linked through edge-to-face (T shape) C-H center dot center dot center dot pi interactions, forming sheets with hydrophobic- (occupied by infinite 2D water-chlorine chains) and hydrophilic- (occupied by chlorine anions) channels. Variable temperature magnetic studies suggest an antiferromagnetic coupling between the adjacent Ni(II) centers with a coupling constant of J = -6.6 cm(-1).