Ruthenium bipyridyl compounds with two terminal alkynyl ligands

Compounds of the form Ru(X(2)bipy) (PPh3)(2)(-C=CC6H4NO2-p)(2) (X(2)bipy = 4,4 - X-2- 2,2'- bipyridine, X = Me 3a, Br 3b, I 3c) have been synthesised from the mono-alkynyl precursors Ru(X(2)bipy) (PPh3)(2)(-C=CC6H4NO2-p) Cl X = Me 2a, Br 2b, I 2c); the former are the first ruthenium bis-alkynyl compounds that also contain a bipyridyl ligand. Spectroelectrochemical investigation of 3a shows that the metal is readily oxidised to form the ruthenium(III) compound 3a(+), and will also undergo a single-electron reduction at each nitro group to form 3a(2-). ESR and UV/visible spectra of these redox congeners are presented. We also report the synthesis of [Ru(Me(2)bipy) (PPh3)(2)( (-C=CBut) (N=N)] [PF6] 4 during the attempted synthesis of Ru(Me(2)bipy) (PPh3)(2)(-C=CBut)(2), and report its X-ray crystal structure and IR spectrum. X-Ray crystal structures of 3b and 3c ( as two different solvates) are presented, and the nature of the intermolecular interactions seen therein is discussed. Z-Scan measurements on Ru(Me(2)bipy) (PPh3)(2)(-C=CR) Cl (R = C6H4NO2-p 2a, Bu-t, Ph, C6H4Me) are also reported, and show that Ru(Me(2)bipy) (PPh3)(2)(-C=CR)-Cl (R = C6H4NO2-p 2a, Ph) exhibit moderate third-order non-linearities.