Reactivity of electrophilic Cp*Ru(NO) complex towards alcohols

Abstract

Treatment of the complex 1 Cp*Ru(NO)(OTf) 2 (OTf = OSO2CF3, Cp* = η 5-C(CH3)5) with neat 2-propanol results in the rapid quantitative formation of the Ru(0) complex [Cp*Ru(μ-NO)] 2 and (CH 3) 2 C=O. Formation of H 2 and CHDCl 2 is detected when the reaction between 1 and 2-propanol occurs in CDCl 3 , indicating possible formation of a short-lived metal hydride species. Similar results are observed upon treatment of 1 with ethanol and methanol, with formation of acetaldehyde and formaldehyde, respectively. The kinetics of the oxidation of 2-propanol by complex 1 is studied by 1 H NMR spectroscopy in CH 2 Cl 2 at variable temperatures and the reaction is found to be first-order in complex 1 and in 2-propanol. The kinetic isotope effect for the reaction of 1 with (CD 3) 2 CD-OD at-11 o C is determined to be k H /k D = 2.0 (3). A mechanism for alcohol oxidation by electrophilic ruthenium (II) complexes via a β-hydrogen elimination step is proposed. The pre-equilibrium exchange step between complex Cp*Ru(NO)(OTf) 2 (1) and alcohol-coordinated species is examined by 19 F and 1 H NMR spectroscopy in CH2Cl2 solution, where triflate substitution is found to be exothermic and entropically unfavorable. The synthesis and solid state structure of the chelate-stabilized complex diol salt [Cp*Ru(NO)(HO-CH 2 CH 2-OH)][2OTf] are discussed.

RuO2 Nanoparticle-Embedded Graphitic Carbon Nitride for Efficient Photocatalytic H2 Evolution

“…The pre-equilibrium process was derived from the adsorption/coordination of the hydroxyl group of TEOA on the RuO 2 surface. The hydroxyl binding on the Ru center has also been proposed in the reported literature. , …”

“…The hydroxyl binding on the Ru center has also been proposed in the reported literature. 65,66 We employed deuterium-labeled water (D 2 O) and ethanol (EtOH-d 6 ) as a solvent and an electron donor, respectively, to investigate the kinetic isotope effects (KIEs) on the photocatalytic H 2 evolution over RuO 2 /g-CN. When H 2 O was replaced with D 2 O, the initial H 2 evolution rate of RuO 2 /g-CN with TEOA was obviously decreased to noticeably 11.4 μmol h −1 (Figure 7a).…”

Alkylgold(III) Complexes Undergo Unprecedented Photo‐Induced β‐Hydride Elimination and Reduction for Targeted Cancer Therapy

“…By using 1 H NMR, a singlet peak at 5.43 ppm was detected after irradiating 1 c in d 6 ‐DMSO for 30 min (Figure 2f), and this peak disappeared after bubbling with N 2 , indicative of forming C 2 H 4 ; [23] for 1 d after light irradiation, 4‐methoxystyrene and [Au(C^N^C)‐(DMSO)] were detected in the LC chromatogram as well (Figure S12). When performing the 1 H NMR experiment in CDCl 3 for 1 c (Figure S13), besides C 2 H 4 (5.40 ppm), CHDCl 2 with a signature 1 : 1 : 1 triplet at 5.28 ppm ( J =1.1 Hz) was detected, suggesting formation of a short‐lived metal‐hydride species [24] . Thus, photo‐induced β‐hydride elimination reaction likely occurred which simultaneously generated alkene and hydride intermediate that further underwent a hydride transfer reaction.…”

“…When performing the 1 H NMR experiment in CDCl 3 for 1 c (Figure S13), besides C 2 H 4 (5.40 ppm), CHDCl 2 with a signature 1 : 1 : 1 triplet at 5.28 ppm (J = 1.1 Hz) was detected, suggesting formation of a short-lived metal-hydride species. [24] Thus, photo-induced β-hydride elimination reaction likely occurred which simultaneously generated alkene and hydride intermediate that further underwent a hydride transfer reaction. For comparison, 1 b containing the methanide ligand slowly decomposed by � 30 % in DMSO after 20 min light irradiation by forming uncharacterizable peaks in the LC chromatogram (Figure S14).…”