Synthesis, structures, characterizations and catalytic behaviors for hydrogen evolution of copper(II) and copper(I) complexes supported by diiminodiphosphines

Abstract

Reactions of N,N’-bis[o-(diphenylphosphino)benzylidene]ethylenediamine (en-P2) with Cu(ClO4)2 or CuClO4 afford two complexes, [CuII-en-P2(NCMe)](ClO4)21 and [CuI-en-P2]ClO42, respectively, which have been characterized by several physico-chemical and spectroscopic methods. The copper atom is five, and four-coordinated in the copper complexes 1 and 2, respectively. At room temperature, en-P2 shows photoluminescence at 420 and 560 nm, however, the addition of Cu2+ or Cu+ leads to a decrease on the peak intensities at 420 and 560 nm, respectively. Investigations for magnetic behaviors show that upon cooling from 300 to 2 K, the χMT value of both copper complexes 1 and 2 steadily increased. Additionally, electrochemical investigations reveal that both complexes 1 and 2 have electrocatalytic activity for hydrogen evolution from acetic acid or water, and complex 1 shows a more efficient activity than complex 2.