Variations in the structural composition of pyrazole-3,5-dicarboxylato Cu(ii) complexes with 1,2-di(4-pyridyl)ethane synthesized under different conditions

Seven new pyrazole-3,5-dicarboxylato Cu( ii ) complexes with 1,2-di(4-pyridyl)ethane were successfully synthesized under various conditions. Moreover, complex 1 exhibits structural transformation through a dissolution–recrystallization process.