Novel rhenium(III) complexes with the picolinate ligand: Synthesis, spectroscopic investigations, X-ray structures and DFT calculations for [ReX2(pic)(PPh3)2] complexes

The paper presents a combined experimental and computational study of novel rhenium(III) complexes with the picolinate ligand – [ReCl2(pic)(PPh3)2] (1) and [ReBr2(pic)(PPh3)2] (2). Both complexes 1 and 2 have been characterised spectroscopically and structurally (by single-crystal X-ray diffraction). Complex 1 has been additionally studied by magnetic measurement. The magnetic behavior is characteristic of a mononuclear d4 low-spin octahedral Re(III) complex (3T1g ground state) and arises because of the large spin–orbit coupling (ζ = 2500 cm−1), which gives a diamagnetic ground state. DFT and time-dependent (TD)DFT calculations have been carried out for complex 1, and UV–vis spectra of the [ReX2(pic)(PPh3)2] compounds have been discussed on this basis.

Graphical abstractThe paper presents a combined experimental and computational study of novel rhenium(III) complexes with picolinate ligand – [ReCl2(pic)(PPh3)2] (1) and [ReBr2(pic)(PPh3)2] (2). The both complexes 1 and 2 have been characterised spectroscopically and structurally (by single-crystal X-ray diffraction). The complex 1 has been additionally studied by magnetic measurement. The magnetic behavior is characteristic of mononuclear complexes with d4 low-spin octahedral Re(III) complexes (3T1g ground state) and arise because of the large spin-orbit coupling (ζ = 2500 cm-1), which gives diamagnetic ground state. DFT and time-dependent (TD)DFT calculations have been carried out for complex 1, and UV–Vis spectra of the [ReX2(pic)(PPh3)2] compounds have been discussed on this basis.Figure optionsDownload full-size imageDownload as PowerPoint slide