Synthesis and structural characterization of new piano-stool ruthenium(II) complexes bearing 1-butylimidazole heteroaromatic ligand

New cationic ruthenium(II) complexes with the formula [Ru(η5-C5H5)(LL)(1-BuIm)] [Z], with (LL) = 2PPh3 or DPPE, and Z = CF3SO3−, PF6−, BPh4−, have been synthesized and fully characterized. Spectroscopic and electrochemical studies revealed that the electronic properties of the coordinated 1-butylimidazole were clearly influenced by the nature of the phosphane coligands (LL) and also by the different counter ions. The solid state structures of the six complexes determined by X-ray crystallographic studies, confirmed the expected distorted three-legged piano stool structure. However the geometry of the 1-butylimidazole ligand was found considerably different in all six compounds, being governed by the stereochemistry of the mono and bidentate coligands (PPh3 or DPPE).

Graphical abstractSix new ruthenium(II) cationic complexes containing 1-butylimidazole ligand. Study of the influence of the coligands and counter ions on the chemical and solid state structural features.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Unexpected redox properties of butylimidazole due interaction with the counter ion. ► Strong effect of coligands and counter ions in butylimidazole conformation. ► Six single crystal structures determined by X-ray diffraction studies.