Synthesis, spectral studies, crystal structures and TDDFT studies of the rhenium(I) complexes of 2,4-dihydroxy-N′-(4-hydroxybenzilidene) benzohydrazide

The rhenium(I) carbonyl bromide complex, [ReBr(CO)3(HL)], of the ligand derived from 2,4-dihydroxybenzaldehyde and 4-hydroxybenzoic acid hydrazide (HL), has been prepared. HL and its complex have been characterized by elemental analysis, MS, IR, UV–Vis and 1H NMR spectroscopic methods. The structure of HL and the aqua-complex [Re(OH2)(CO)3(L)] where the ligands are monodeprotonated have been elucidated by X-ray diffraction. The structure of [ReBr(CO)3(HL)] has been calculated from conformational parameters found in the aqua-complex. DFT and TDDFT calculations have been performed to obtain the IR spectra and UV–Vis absorption and emission spectra. The calculated spectra agree with the experimental results.

Graphical abstractReBr(CO)3(HL), of the ligand derived from 2,4-dihydroxybenzaldehyde and 4-hydroxybenzoic acid hydrazide (HL), has been prepared. The structure of HL and the aqua-complex [Re(OH2)(CO)3(L)] have been elucidated by X-ray diffraction. Spectroscopic properties (IR and UV–Vis) of [ReBr(CO)3(HL)] obtained by DFT and TDDFT calculations agree with the experimental results.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► We obtain a new hydrazone ligand and its complex [ReBr(CO)3(HL)]. ► The structure of HL and the aqua-complex [Re(OH2)(CO)3(L)] is elucidated by X-ray diffraction. ► We calculate the structure of bromine complex from structural parameters found in the aqua complex. ► Spectroscopic properties obtained by DFT and TDDFT calculations agree with the experimental.