Syntheses, structures and redox properties of tris(pyrazolyl)borate-capped ruthenium vinyl complexes

Reaction of RuHCl(CO)(PPh3)3 with aryl alkynes HCCC6H4R-4 [1: R = N(C6H4Me-4)2 (a), OMe (b), Me (c), CO2Me (d), NO2 (e)] gives the five-coordinate vinyl complexes Ru(CHCHC6H4R-4)Cl(CO)(PPh3)2 (2a–e). Reaction of 2a with excess PMe3 gives crystallographically characterised Ru{CHCHC6H4N(C6H4Me-4)2-4}Cl(CO)(PMe3)3 (3a), whilst reaction of 2a–e with KTp affords Ru(CHCHC6H4R-4)(CO)(PPh3)Tp (4a–e) bearing the facially capping Tp− ligand. Electrochemical and spectroelectochemical properties of 4a–e are consistent with substantial redox activity associated with the vinyl ligand, and these properties have been satisfactorily modelled by DFT based calculations of electronic structure.

The electrochemical and spectroelectochemical properties of complexes Ru(CHCHC6H4R-4)(CO)(PPh3)Tp bearing the facially capping Tp− ligand are consistent with substantial redox activity associated with the vinyl ligand, and these properties have been satisfactorily modelled by DFT based calculations of electronic structure.Figure optionsDownload as PowerPoint slideHighlights
► Ruthenium vinyl complexes featuring a Tp co-ligand have been prepared.
► The vinyl ligand is redox-active.
► DFT and TD DFT calculations support the experimental results.