Novel oxorhenium(V) complexes of 8-hydroxyquinoline derivatives – Synthesis, spectroscopic characterization, X-ray crystal structures and DFT calculations

Two modifications of 8-hydroxyquinoline framework, namely 5,7-dichloro-2-[2-(2-chlorophenyl)vinyl]quinoline-8-ol (HL1) and 2-[2-(3,4-dichlorophenyl)vinyl] quinoline-8-ol (HL2) have been synthesized and their interaction with [ReOX3(PPh3)2] (X = Cl, Br) have been examined. HL1 and HL2 react with [ReOX3(PPh3)2] to give [ReOCl2(L1)(PPh3)]2·MeCN (1), [ReOBr2(L1)(PPh3)] (2), [ReOCl2(L2)(PPh3)] (3) and [ReOBr2(L2)(PPh3)] (4). The complexes have been characterized spectroscopically and structurally. The experimental studies on 1 and 3 have been accompanied by DFT calculations, and additional information about binding between the rhenium atom and oxo ligand has been obtained by NBO analysis. The X-ray studies and NBO analysis confirm a triple bond between the rhenium and the terminal oxo ligand. The L1 and L2 ligands coordinate in a chelate way via N- and O-donor atoms, and the oxygen donor of the chelate ligand is located trans to the terminal oxo (Ot) group due to a strong trans-influence of Ot ligand. DFT and TD-DFT calculations applied to 1 and 3 resulted in appropriate prediction of the UV–Vis spectra and enabled a detailed assignment of the electronic transitions to the experimental absorptions.

The paper concerns two modifications of 8-hydroxyquinoline framework, 5,7-dichloro-2-[2-(2-chlorophenyl)vinyl]quinoline-8-ol (HL1) and 2-[2-(3,4-dichlorophenyl)vinyl] quinoline-8-ol (HL2) and their interaction with [ReOX3(PPh3)2] (X = Cl, Br). The purity and structures of HL1 and HL2 were determined by means of HPLC, NMR and mass spectroscopy. The oxorhenium(V) complexes [ReOCl2(L1)(PPh3)]2·MeCN (1), [ReOBr2(L1)(PPh3)] (2), [ReOCl2(L2)(PPh3)] (3) and [ReOBr2(L2)(PPh3)] (4) were characterized spectroscopically and structurally. The experimental studies on compounds 1 and 3 were accompanied by DFT calculations. Additional information about binding between the rhenium atom and oxo ligand in the complexes was obtained by NBO analysis.Figure optionsDownload as PowerPoint slide