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

The
tetranuclear nickel­(II) complex [Ni4(HL)4]­Cl4·4H2O {H2L = 1,5-bis­[1-(pyridin-2-yl)­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 × 2 square grid of tetramer
units with the metal ions joined in pairs by the alkoxide oxygen atom
in the μ2 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···π
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.