Simple Catalyst Based on Zinc(II) Iodide for the Synthesis of Cyclic Carbonates

Abstract

The reaction of tridentate ligand 2,6-bis(5-(tert-butyl)-1H-pyrazol-3-yl)pyridine (L) and zinc(II) iodide affords a new zinc(II) complex LZnI₂. The compound is isolated in the individual state and characterized by NMR spectroscopy, and its single crystal LZnI₂∙2C₃H₇NO is characterized by X-ray diffraction (XRD) (CIF file CCDC no. 2447394). The synthesized complex demonstrates a catalytic activity in the reactions of CO₂ with substituted oxiranes with the formation of cyclic carbonates. This is due to the simultaneous presence in the catalyst of the metal Lewis acidic site capable of coordinating epoxide, nitrogen Lewis basic site providing CO₂ fixation, and nucleophilic iodide ion that activates epoxide ring opening. The development of the proposed approach to the design of catalysts will possibly simplify the preparation of efficient systems for the reactions of carbon oxide with three-membered heterocycles.