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

Abstract

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) Å, b = 9.638(1) Å, and c = 20.011(2) Å with V = 5137.5(7) ų for Z = 4. The anion shows a chloride-bridged binuclear structure with Cu ··· Cu distance of 3.872 Å; 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.

Keywords:

• Binuclear multichlorocuprate(II)
• 4-Nitrobenzyl-4′-dimethylaminopyridinium
• Chloride-bridged
• Crystal structure
• Antiferromagnetic interaction

Acknowledgments

This work has been partially supported by the Guangdong Natural Science Foundation (No. 10151064201000022), the key Academic Program of the 3rd phase “211 Project” of South China Agricultural University (No. 2009B010100001), the university students’ innovative experimental project (No. 1056410002) from Education Department of Guangdong Province, and the Science and Technology Project (No. 2011B080701026) from Guangdong Science and Technology Department.