Pentaammineruthenium(II), pentaammineosmium(II), and (N-(hydroxyethyl)ethylenediaminetriacetato)ruthenate(II) complexes of styrenes

Substituent dependency in pentaamminemetal(II) complexes (M = Ru, Os) of styrenes probed by using carbon-13 nuclear magnetic resonance spectroscopic method and voltammetrical analysis

“…An inflection apparently arises in the correlation lines with slopes -4.620 (r = 0.9448) and -1.218 (r = 0.9408) for Cp and C,, respectively. When a substituent is changed, Cp shows a change in chemical shift with a higher sensitivity than C,, indicating a preferential coordination of the metal centers to the exo vinyl stated previously by Shepherd et al (2). This fact resembles that of anionic Pt-styrene compound series (4).…”

“…The olefin pentaamineruthenium complexes have been synthesized and studied using electrochemical and spectroscopic techniques (2). The cyclic voltammetric (CV) analysis of styrene pentaamineruthenium(I1) chloride shows that the interaction between the vinyl group of styrene and ruthenium is independent of the substituent on the phenyl ring (2). NMR spectrometry is a very sensitive tool which can determine the electron density of nucleus in organic as well as organometallic compounds.…”

The fragment bis(acetylacetonato)ruthenium: a meeting-point of coordination and organometallic chemistry

“…A deep violet vinylidene isomer (11) of [Ru(acac) 2 (o-HC"CC 6 H 4 NMe 2 )] (10) is formed in small amounts in the preparation of the latter by the usual [Ru(acac) 3 ]/Zn procedure; it is more conveniently obtained by exposure of solutions of the crude trimethylsilyl-substituted compound 9 to air for 24 h [55]. Compound 11 itself contains two isomers, 11a and 11b, which can be separated by fractional crystallization from hexane.…”

“…The presence of p-acceptor ligands in the coordination sphere of octahedrally coordinated ruthenium tends to stabilize the occupied metal p-orbitals (HOMO) and reduce the interelectronic repulsion in the metal ion, thus stabilizing Ru II ðt 6 2g Þ relative to Ru III ðt 5 2g Þ. Thus, the reduction potentials E 1/2 of the Ru III /Ru II couple for [Ru(NH 3 ) 5 (g 2 -alkene)] 2+ complexes range from +0.83 V (alkene = propene) [10] to +0.98 V (alkene = styrene [11]), corresponding to a stabilization of the Ru II level of ca. 0.75 V compared to [Ru(NH 3 ) 6 ] 2+ (E 1/2 = +0.05 V vs. NHE) [12].…”

“…A similar trend is evident in the E 1/2 values (vs. NHE) for the aqua ions [Ru(H 2 O) 6 ] 2+ (+0.19 V) [13] and [Ru(H 2 O) 5 (g 2 -C 2 H 4 )] 2+ (+0.84 V) [14]. The electrogenerated one-electron oxidation products, [Ru(NH 3 ) 5 (g 2 -alkene)] 3+ and [Ru(H 2 O) 5 (g 2 -alkene)] 3+ , have not been isolated or detected, because the alkene is probably weakly bound at the Ru III level and is replaced rapidly by the solvent (usually water) in which the cyclic voltammetry is performed [10,11,15]. It is generally assumed that metal-ligand back-bonding is negligible at the Ru III level, though the same may not be true for Os III .…”