Two phosphine ruthenium(III) and ruthenium(II) complexes with the pyrazole ligand - Synthesis, characterisation and DFT calculations

The [RuCl3(PPh3)2(HPz)]·C6H6 and t,t,t-[RuCl2(PPh3)2(HPz)2]·2C6H6 complexes have been obtained in the reaction of [RuCl3(PPh3)3] with pyrazole, and characterized by IR, UV-Vis and NMR spectroscopies. The crystal and molecular structures of the complexes have been determined by X-ray crystallography. Based on the molecular geometries, the electronic structures and UV-Vis spectra of the complexes have been calculated using the DFT and TD-DFT methods. A discussion on the stability of the two isomers of the [RuCl2(PPh3)2(HPz)2] complex, based on an analysis of overlap partial density-of-state diagrams, has been presented.