Synthesis, crystal, molecular and electronic structure of the [ReCl 4(pzH)(PPh 3)] and [ReCl 4(pyz)(PPh 3)] complexes

Abstract

The reactions of the [ReCl 4(PPh 3) 2] complex with pyrazole (pzH) and pyrazine (pyz) have been examined and two novel Re(IV) compounds – [ReCl 4(pzH)(PPh 3)] ( 1) and [ReCl 4(pyz)(PPh 3)] ( 2) – have been obtained. The compounds have been studied by IR, UV–Vis spectroscopy and X-ray crystallography. The electronic structures of 1 and 2 have been calculated with the density functional theory (DFT) method. The spin-allowed quartet–quartet electronic transitions of 1 and 2 have been calculated with the time-dependent DFT method, and the UV–Vis spectra of the title compounds have been discussed on this basis. From magnetic studies a small, negative value of J obtained confirms the occurrence of weak antiferromagnetic interactions between the rhenium centers in the crystal lattice.