Synthesis and characterization of copper(I) compounds incorporating pyrazole-derived ligands: A study on carbon–carbon coupling reaction

• Copper(I) compounds incorporating pyrazole mediated precursor.
• Sonogashira type C–C coupling.
• X-ray crystal structure of copper(I) derivatives.
• Cyclic voltammetry measurements.

A series of copper(I) compounds manifesting with the pyrazole mediated precursor, ArN[CH2(C3H3N2)]2 (Ar = 2,6-diisopropylphenyl) (LN3), were synthesized conveniently and treatment of the derivatives with small organic molecules like pyrazine and triphenylphosphine were analyzed. Reacting one and two equivalents of LN3 with [Cu(CH3CN)4]PF6 in CH3CN at room temperature afforded [Cu(LN3)(CH3CN)2]PF6 (1) and [Cu(LN3)2]PF6 (2), respectively in high yield. Similarly, while reacting one equivalent of LN3 and CuI in acetonitrile for 12 h, produced a white solid, [Cu(LN3)]I (3). Furthermore, by adding one or two equivalents of PPh3 into compound 1, using methylene chloride as solvent rendered [Cu(LN3)(PPh3)]PF6 (4) and [Cu(LN3)(PPh3)2]PF6 (5), respectively, in satisfactory yield. In addition, compound {[Cu(LN3)(C4H4N2)]2(PF6)2}n (6) was generated as one-dimensional polymer by treating compound 1 and pyrazine in THF at room temperature. All the Cu(I)-derivatives were characterized by 1H and 13C NMR spectroscopy and the molecular structures (1, 4, and 6) were determined by single crystal X-ray diffraction. Additionally, the catalytic reactions of Sonogashira type C–C coupling were discussed using compounds 2, 3, 5, and 6 as catalysts.

A series of Cu(I) complexes incorporating pyrazole-derived ligands are synthesized and characterized. The catalytic reactions of Sonogashira type C–C coupling are governed and cyclic voltammetry analysis are also performed.Figure optionsDownload as PowerPoint slide