Discrete copper(i) chalcogenones with metal–metal interaction

Abstract

The Cu⋯Cu interactions, known as cuprophilicity, play a significant role in copper–chalcogenide functional materials. Three dinuclear copper chalcogenone complexes, [(L¹CuI)₂] (1), [(L²CuI)₂] (2) and [Cu₂(L³)₄]PF₆ (3), have been isolated and characterized. L¹ = 1-(9-methyl anthracene)-2-isopropyl-benzimidazole-2-thione; L² = 1-(9-methyl anthracene)-2-isopropyl-benzimidazole-2-selenone and L³ = 1-pyridine-2-isopropyl-imidazole-2-selenone, ligands and 1–3 were characterized by ¹H NMR, ¹³C NMR, FT-IR, and SCXRD. Complexes 1 and 2 compress a four-membered strained ring system bridged by iodine, whereas 3 consists of a similar-four-membered ring core bridged by a selenium ligand. The Cu⋯Cu interactions in the crystal structures are observed (2.591 Å for 1, 2.576 Å for 2, and 2.523 Å for 3). The bridging ligand shows a key contribution to the Cu⋯Cu interactions. The density functional theory calculations also confirm the presence of d¹⁰⋯d¹⁰ interactions, which are predominantly covalent in nature. The computational study also shows the effect of the bridged ligands on the d¹⁰⋯d¹⁰ interactions and overall stability of the complexes, where complex 2 is the most stable followed by 1, and after that 3, although the d¹⁰⋯d¹⁰ interactions were the strongest in the case of 3.