Synthetic methodology, structures and properties of mixed valence copper(I/II) complexes with various Schiff bases and their reduced analogues

• Published in: Polyhedron 2021-05, Vol.199, p.115086, Article 115086
• Main Authors: Kumar Bhaumik, Prasanta, Chattopadhyay, Shouvik
• Format: Article
• Language: English
• Subjects: Copper(I); Copper(II); Mixed valence; Schiff bases and their reduced analogues; Synthesis and properties
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2021.115086

Syntheses, structures and properties of different mixed valence copper(I/II) complexes with Schiff bases and their reduced analogues were reported in literature. This review focuses light on relative merits and demerits of different synthetic procedures. At the same time, the structures and properties of these complexes were also compared. The review also identifies the less explored areas of applications of these mixed valence complexes. [Display omitted] A variety of mixed valence copper(I/II) Schiff base complexes have been gathered and a comparative study has been made focusing on their, syntheses, structures and properties. Different synthetic strategies have been applied for their preparation. In most of the cases, mixed valence complexes have been synthesized by the in situ partial reduction of copper(II) to copper(I) by different reducing agents. However, aerial oxidation of copper(I) has also been identified as another synthetic route. Macrocyclic and polyhydroxy Schiff base ligands have been carefully utilized in some cases to produce high nuclearity mixed valence complexes. Certain reduced analogues of these Schiff bases have also been utilized to prepare mixed valence copper(I/II) complexes, where CuBr32− anion has acted as a bridge between the copper(II) centers. Pseudohalides like thiocyanate, cyanide, etc have played dual roles of reducing agents and bridging ligands as well in the synthesis of some mixed valence complexes. Several properties like magnetic, catalytic etc, investigated by different groups are also highlighted in this review. The less explored areas of potential applications of these mixed valence complexes are also discussed.