Coordination chemistry of di-2-pyridylketone. Synthesis, spectroscopic investigations, X-ray studies and DFT calculations of Re(III) and Re(V) complexes

The paper presents a combined experimental and computational study of Re(III) and Re(V) complexes containing di-2-pyridylketone and its gem-diol form – [ReCl3(dpk-N,O)(PPh3)] (1), [ReCl3(dpk-N,N′)(OPPh3)] (2) and [ReOBr3(dpk-OH)]·2(dpkH+Br−) (3). All the complexes have been characterized spectroscopically and structurally (by single-crystal X-ray diffraction). The complex 2 has been additionally studied by magnetic measurement. The magnetic behavior of 2 is characteristic of mononuclear octahedral Re(III) complex with d4 low-spin (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 [ReCl3(dpk-N,N′)(OPPh3)] and [ReOBr3(dpk-OH), and their UV–vis spectra have been discussed on this basis.

Graphical abstractThe paper presents a combined experimental and computational study of Re(III) and Re(V) complexes containing di-2-pyridylketone and its gem-diol form – [ReCl3(dpk-N,O)(PPh3)] (1), [ReCl3(dpk-N,N′)(OPPh3)] (2) and [ReOBr3(dpk-OH)]·2(dpkH+Br−) (3). All the complexes have been characterized spectroscopically and structurally (by single-crystal X-ray diffraction). The complex 2 has been additionally studied by magnetic measurement. The magnetic behavior is characteristic of mononuclear octahedral Re(III) complex with d4 low-spin (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 [ReCl3(dpk-N,N′)(OPPh3)] and [ReOBr3(dpk-OH), and their UV–vis spectra have been discussed on this basis.Figure optionsDownload full-size imageDownload as PowerPoint slide