A New Quartz-like Metal–Organic Framework Constructed from a Versatile Pyrazole-Based Spacer

Two
new coordination polymers, 1∞[Cu2(L)4­(MeOH)]­·MeOH (1) and 3∞[Cu­(L)2]­·5H2O (2), have been obtained exploring the potential
of 5-amino-1-phenyl-1H-pyrazole-4-carboxylate (L–) to act as a spacer. The different architectures of
these compounds arise from the versatility of this organic ligand.
In compound 1, the carboxylato groups (syn-syn bridging
mode) and the copper ions generate a binuclear paddle-wheel motif.
Each binuclear entity coordinates to another one, through one out
of the four pyrazole rings, resulting in double chains. In crystal 2, the organic ligand is coordinated to a copper ion through
the carboxylato group (asymmetric chelating) and to another copper
ion through the pyrazole nitrogen atom. Compound 2 crystallizes
in the hexagonal system with the chiral space group P6122, featuring a quartz-like topology. The magnetic properties
of both compounds have been investigated.