Sustainable dipolar homo-dicopper (II) dihydrazone complex as a catalyst for Sonogashira cross couplings

A novel dicopper (II) complex, Cu2L, was prepared form the complexation of the new polydentate ligand (H4L), bis(sodium 3-formyl-4-hydroxybenzenesulfonate)succinylhydrazone, with copper acetate. The novel homobinuclear complex was quite characterized by various physico-chemical tools and employed as a homogeneous and efficient-green catalyst for Sonogashira cross-couplings of phenylacetylene with halobenzenes under sustainable conditions. Cu2L exhibited very good catalytic performance with excellent chemoselectivity. The catalytic efficiency of Cu2L was improved by using ionic liquids-aqueous media (1: 1, binary mixture). A mechanistic pathway was also proposed for Cu(II)-catalyzed Sonogashira cross-coupling reactions for the reported finding. DFT for H4L and Cu2L were studied. Electronic configurations, energy of HOMO and LUMO orbitals, energy gap between orbitals (DE), electronegativity, hardness and softness were also calculated and compared with the applicable catalytic findings of Cu2L, which are in good conformity. (c) 2019 Elsevier B.V. All rights reserved.