Strong antiferromagnetic interaction in a 3D copper–organic framework and spin-glass-like behaviour in a 1D nickel compound

Abstract

The in situ hydrothermal reaction of 5-(4-carboxy-1H-1,2,3-triazol-1-yl)isophthalic acid (H₃ctia) with M(NO₃)₂·nH₂O (M = Cu, Ni) afforded two new coordination polymers, {[Cu₄(tia)₄(H₂O)₃]·H₂O}_n (1) and {Ni(H₂O)₆·[Ni₂(ctia)₂(H₂O)₆]·2H₂O}_n (2) (tia²⁻ = 5-(1H-1,2,3-triazol-1-yl)isophthalate). X-ray structural analysis reveals complex 1 is an unusual 3D framework containing D_4h paddle-wheel copper units and two kinds of mononuclear copper units, and its resulting structure can be rationalized as a new topology with the Schläfli symbol of {4.8²}2{4².8⁵.10⁶.12²}{8².10}2{8³}2. Compound 2 displays a 1D zigzag chain structure. Strong antiferromagnetic interactions are observed among dinuclear units in complex 1. Interestingly, complex 2 exhibits spin-glass-like behaviour with the spin glass freezing temperature at 15.8 K. In addition, the thermal stability of these compounds was also studied.