Combined Experimental and Computational Study of Cis-Trans Isomerism in N,N-Disubstituted-N’-Acylthiourea Ligands in Bis-Chelated Copper(Ii) Complexes

The synthesis, molecular structure determination and a Density Functional Theory (DFT) investigation of the structure of several new complexes of copper(II) with nine N,N-disubstituted-N’-acylthiourea (HL) ligands is reported. Characterisation of these complexes was achieved using a combination of FT-IR, 1H & 13C NMR and single crystal X-ray diffraction analysis. The XRD studies revealed the presence of a distorted square planar geometry for all the complexes synthesised. It was found that fine tuning the Acyl and NRR’ substituent of the complexes can afford some level of control in terms of the cis or trans outcome for the compounds. DFT studies were performed to investigate the cis/trans isomerism. The calculations found a difference in energy between the two isomers smaller than 1.2 kcal mol-1, suggesting that the two conformations are equally possible for all copper(II) complexes.