Influence of structural properties of zinc complexes with N4-donor ligands on the catalyzed cycloaddition of CO2 to epoxides into cyclic carbonates

•Zn(II)-N4-donor ligands complexes were prepared and fully characterized.•The computational stability predictions agree with X-ray diffraction data.•Cyclic carbonates were selectively obtained with Zn-N-donor/TBAB catalytic systems 1,2-epoxihexane carbonate TOF 565 h−1.•Relation between catalytic activity and structural characteristics of Zn complexes is stablished. Zinc(II) complexes [Zn(L1-L5)Cl2] with tetra-aza donor ligands bearing phenanthroline and bipyridine bis(aniline) skeleton L1-L5 have been prepared and characterised. These ligands were selected to analyse the influence on the catalytic activity for the CO2-cycloaddition to epoxides of three parameters: the steric hindrance of the orto substituent of the aniline ring, the central skeleton and the nature of the non-aromatic amine. X-ray diffraction characterisation of [Zn(L1)Cl2] and [Zn(L2)Cl2] showed that the geometry is pentacoordinate while in the case of [Zn(L5)Cl2] a four-coordinate tetrahedral complex was formed. Computational calculations using density functional theory methods (DFT) agreed with these results. These complexes combined with tetrabutylammonium bromide (TBAB) are very selective for the CO2/terminal epoxides coupling to form cyclic carbonates providing activity up to TOF 565 h−1. [Display omitted]