Substituent’s size in pyrazole derivative ligands as determining factor on nuclearity in Cu(II) complexes

New copper(II) nitrate compounds [Cu(μ-NO3)(NO3)(PyTn)]n (1), [{Cu(NO3)(DMPyTn)}2(μ-NO3)2] (2) and [Cu(NO3)2(DPhPyTn)] (3) containing pyrazole/thiazoline ligands [PyTn = 2-(pyrazol-1-yl)-2-thiazoline; DMPyTn = 2-(3,5-dimethylpyrazol-1-yl)-2-thiazoline; DPhPyTn = 2-(3,5-diphenylpyrazol-1-yl)-2-thiazoline] have been synthesized and characterized by elemental analysis, IR, electronic spectra, ESI-MS, thermal analysis, magnetic susceptibility measurements and single crystal X-ray diffraction. With respect to the environment around copper(II), complexes 1 and 2 are five-coordinate with a geometry of distorted square pyramid whereas 3 is six-coordinate with octahedral geometry. The role played by ligands substituents size on nuclearity of complexes has been analyzed. Thus, 1 is a polymer, 2 is a dimer and 3 presents a monomeric structure. This could be a consequence of the steric strain induced by the organic ligands.

Three copper(II) nitrato complexes with pyrazole/thiazoline derivative ligands with different steric features have been prepared and structurally characterized. The role played by ligands substituents size on nuclearity of complexes has been analyzed.Figure optionsDownload as PowerPoint slide