Copper(I) complexes bases on a new indazol-4,7-dione ligand

• Published in: Polyhedron Vol. 62; pp. 66 - 74
• Main Authors: Escobar, Manuel A., Jara, Danilo H., Tapia, Ricardo A., Lemus, Luis, Fröhlich, Roland, Guerrero, Juan, Rojas, René S.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 07-10-2013
• Subjects: Copper(I) complex; Heteroleptic copper(I); Homoleptic copper(I); Indazol-4,7 dione; Homoleptic copper(I); Heteroleptic copper(I); Copper(I) complex; Indazol-4,7 dione
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2013.06.020

The synthesis of two new isomeric ligands, 1-(1-((2,6-diisopropylphenyl)imino)ethyl)-1H-benzo[f]indazole-4,9-dione (La) and 2-(1-((2,6-diisopropylphenyl)imino)ethyl)-2H-benzo[f]indazole-4,9-dione (Lb), and of their [Cu(I)(Lb)2] (ClO4) (1) homoleptic and [Cu(I)(Lb(PPh3)2] (ClO4) (2) heteroleptic copper(I) complex derivatives is reported. The chemical stability, and the spectroscopic and electrochemical properties of the complexes are discussed.
Two new isomeric ligands, 1-(1-((2,6-diisopropylphenyl)imino)ethyl)-1H-benzo[f]indazole-4,9-dione (La) and 2-(1-((2,6-diisopropylphenyl)imino)ethyl)-2H-benzo[f]indazole-4,9-dione (Lb), were synthesized and fully characterized as well the derivative copper complexes; [CuI(Lb)2] (ClO4) (1) homoleptic and [CuI(Lb(PPh3)2] (ClO4) (2) heteroleptic copper(I) complexes.
The X-ray diffraction shows an irregular tetrahedral coordination around of metal in both monometallic complexes with little differences in Cu–N distances and N–Cu–N bite angles than involved the indazole ligand between two complexes.
The proton spectra show a different variation in chemical shift relative to free ligand, which was discussed by steric and magnetic current effects of another coordinated ligand. The differences in the energy of metal-to ligand-charge-transfer (MLCT) and in redox potentials to CuII/CuI process in both complexes show the notorious influence of the phosphine which by back-donating effect, modified the energy of HOMO orbital centered in Cu atom. The coordinative and redox stability in solution was established for several days in non-coordinating solvent. However in acetonitrile the ligand substitution is very fast.