Copper(II) complexes with 4-(3,5-dimethyl-1H-pyrazol-1-yl)-2-methyl-6-phenylpyrimidine: Syntheses, crystal structures and catalytic activity in ethylene polymerization

The copper(II) complexes CuLCl2 (1) and CuLBr2 (2), with the chelating pyrazolylpyrimidine ligand 4-(3,5-dimethyl-1H-pyrazol-1-yl)-2-methyl-6-phenylpyrimidine (L), have been synthesized. A single crystal X-ray diffraction study revealed that 1 and 2 have molecular mononuclear structures. The molecules of 1 and 2 form chains in the crystal structures of these compounds due to the formation of π–π-stacking interactions between the pyrimidine and the phenyl rings. The complexes, in combination with the co-catalyst methylaluminoxane (MAO), reveal catalytic activity in ethylene polymerization, while the free ligand L is inactive.

Graphical abstractTwo molecular mononuclear copper(II) complexes with 4-(3,5-dimethyl-1H-pyrazol-1-yl)-2-methyl-6-phenylpyrimidine (L), CuLCl2 and CuLBr2, have been synthesized. Double π–π-stacking interactions between the pyrimidine and phenyl rings of the coordinated L molecules are observed in the structures of the complexes. The complexes, in combination with the co-catalyst methylaluminoxan, reveal catalytic activity in ethylene polymerization.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Cu(II) complexes with a 4-pyrazolylpyrimidine ligand. ► Double π–π stacking interactions. ► Formation of supramolecular self-assemblies. ► Catalytic activity in ethylene polymerization.