From 0 to II in One‐Electron Steps: A Series of Ruthenium Complexes Supported by TropPPh₂

Abstract

We report the synthesis of a series of ruthenium complexes supported by the phosphine olefin ligand tropPPh2 (trop=5‐H‐dibenzo‐[a,d]cyclohepten‐5‐yl) in the oxidation states 0, +I, and +II, formed via successive one‐electron oxidization steps from Ru0(tropPPh2)2. The bidentate character of the tropPPh2 ligand and its steric hindrance force the complexes to adopt uncommon geometries, which were investigated by X‐ray diffraction analysis. EPR data of the mononuclear RuI complex reveal couplings of the unpaired spin with the ruthenium and two phosphorus nuclei, as well as the olefinic protons which show that the spin is mainly localized on the RuI center.

Ruthenium complexes of 1,4-diazabutadiene ligands with a cis-RuCl2 moiety for catalytic acceptorless dehydrogenation of alcohols: DFT evidence of chemically non-innocent ligand participation

“…Generation of ruthenium(0) species bearing soft ligands is precedent in literature. 29 Scheme 3 shows a sequence of events that serves to convert cis - 1 to the κ 1 - O -benzaldehyde complex E . The activation of cis - 1 by the alcohol substrate was experimentally examined using ethanol at room temperature.…”

“…Generation of ruthenium(0) species bearing soft ligands is precedent in literature. 29 Scheme 3 shows a sequence of events that serves to convert cis -1 to the κ 1 - O -benzaldehyde complex E. The activation of cis -1 by the alcohol substrate was experimentally examined using ethanol at room temperature. Treatment of cis -1 with ethanol led to a slow increase in the solution conductivity ( Λ = 12.0 S cm 2 mol −1 ) over the course of several hours in support of the ion pair [Ru(DAB-H) 2 (EtOH)Cl][Cl].…”

Highly Efficient Base‐Free Dehydrogenation of Formic Acid at Low Temperature

“…[6a] Further examples [8b] of base-free FA dehydrogenation include various Ir catalysts reported for example, by the groups of Himeda, [24,25] Fujita, [25] Reek, [15a] and Li, [26] as well as Rh-PNC [27] and Ru-PNNNP 2 [28] pincercomplexes. In addition to the dihydride complexes, [RuCl 2 (PPh 3 ) 3 ]( 4)a nd the Ru 0 complex [Ru(tropPPh 2 ) 2 ]( 6) [32] were also tested for comparison. [29][30][31] Herein, we describe the selective dehydrogenation of formic acid by using mostly well-knowno rganometallic ruthenium hydride complexes that are active at low temperature without any additives.W es tarted the project by testing four different ruthenium dihydride complexes (1-3 and 5,S cheme 2).…”

“…[29][30][31] Herein, we describe the selective dehydrogenation of formic acid by using mostly well-knowno rganometallic ruthenium hydride complexes that are active at low temperature without any additives.W es tarted the project by testing four different ruthenium dihydride complexes (1-3 and 5,S cheme 2). In addition to the dihydride complexes, [RuCl 2 (PPh 3 ) 3 ]( 4)a nd the Ru 0 complex [Ru(tropPPh 2 ) 2 ]( 6) [32] were also tested for comparison. In preliminarye xperiments, the following conditions were applied: 3.3 m formic acid solution in THF and catalyst loading of 0.05 mol %i nt he presence of 2equivalents of water at 25 8C.…”