Synthesis, crystal structure, and magnetic properties of a salt containing [Cu₂Cl₇]³⁻ and 4-nitrobenzyl-4′-dimethylaminopyridinium

A new salt, [NO2BzDMAP]3[Cu2Cl7] · H2O (1), has been synthesized, where [NO2BzDMAP]+ is 1-(4′-nitrobenzyl)-4-dimethylaminopyridinium. Herein, the synthesis, spectral and structural characterization, and magnetic behavior of 1 are reported. It is orthorhombic, with space group Pca21, and a = 26.639(2) A, b = 9.638(1) A, and c = 20.011(2) A with V = 5137.5(7) A3 for Z = 4. The anion shows a chloride-bridged binuclear structure with Cu ··· Cu distance of 3.872 A; the two Cu(II) ions have a tetrahedral geometry. The cations stack through p ··· π and π ··· π interactions, and a complicated hydrogen-bonding network structure is formed through C–H ··· Cl and C–H ··· O hydrogen bonds. The variable temperature magnetic susceptibility measurements reveal that 1 exhibits strong antiferromagnetic interaction with J = −193.0 cm−1.