Dinuclear copper(I) complexes of tris(3,5-dimethylpyrazol-1-yl)methane: Synthesis, structure, and reactivity

The reaction of [Cu(NCMe)4](BF4) with equimolar amounts of the tris(substituted-pyrazolyl)methane ligand HCPz3 or HC(3,5-Me2Pz)3 yields the respective salts [Cu(HCPz3)(NCMe)](BF4) (1a) or [Cu(HC(3,5-Me2Pz)3)(NCMe)](BF4) (1). The acetonitrile ligand of 1 can be replaced by prazine, 4,4′-dipyridine or 1,4-diisocyanobenzene to yield related mononuclear complexes [Cu(HC(3,5-Me2Pz)3)(pyrazine)](BF4) (2), [Cu(HC(3,5-Me2Pz)3)(4,4′-bipyridine)] (BF4) (3) or [Cu(HC(3,5-Me2Pz)3)(1,4- CNC6H4NC)](BF4) (7), respectively. A series of binuclear copper(I) complexes {[Cu(HC(3,5-Me2Pz)3)]2(μ -BL)}(BF4)2 (4, BL = pyrazine; 5, BL = 4,4′-dipyridine; 8, BL = 1,4-diisocyanobenzene) were prepared by treating equal molar ratio of 1 with related mononuclear complexes 2, 3 and 7. In addition, binuclear copper(I) complexes were also prepared from treatment of 2 equiv of 1 with the related bridge ligand. Both of 4 and 5 reformed mononuclear starting complex 1 in acetonitrile solution. However, the more robust complex 8 was stable in acetonitrile solutions. The structure of complexes 1a, 4, 5, and 7 were confirmed by X-ray crystallography. The redox properties of 4 and 8 were examined by cyclic voltammetry and exhibited two quasi-reversible waves suggesting that no significant structural reorganization occurs during the redox process on the electrochemical time scale.

Graphical abstractA family of mononuclear and dinuclear copper(I) complexes were prepared and characterized with tris(3,5-dimethylpyrazol-1-yl)methane containing pyrazine, 4,4′bipyridine, and 1,4-diisocyanobenzene bridge ligand.Figure optionsDownload full-size imageDownload as PowerPoint slide