Denticity governs the formation of β-thioketiminato tri-copper(i) and mono-copper(i) complexes

Abstract

Two classes of β-thioketiminate ligands, SN chelators (HL₁ and HL₂) and SNN chelators (HL₃ and HL₄), were prepared to understand their coordination behavior in copper(I) complex formation. The formation of these copper(I) complexes bearing β-thioketiminate ligands and their corresponding adducts toward isocyanide, PPh₃, and CO was investigated to address two important issues. First, whether the denticity governs the copper(I) thiolate species formation between SN chelators and SNN chelators. Second, how the length of the pendant pyridyl arm affects the coordination and reactivity behaviors of copper(I) complexes. Based on the characterization results, it was found that the denticity of SN chelators and SNN chelators led to different nuclearity of copper(I)–thiolate species. The coordination modes of the pendant pyridyl arm were confirmed by FTIR measurements, which allow us to conclude that the electron donating ability of the LCu fragment is in the order of SNN-chelator (SNN bound) > SNN-chelators (SN bound) > SN-chelator.