We report here the first purely organometallic fac‐[MnI(CO)3(bis‐MeNHC)Br] complex with unprecedented activity for the selective electrocatalytic reduction of CO2 to CO, exceeding 100 turnovers with excellent faradaic yields (η
CO≈95 %) in anhydrous CH3CN. Under the same conditions, a maximum turnover frequency (TOFmax) of 2100 s−1 was measured by cyclic voltammetry, which clearly exceeds the values reported for other manganese‐based catalysts. Moreover, the addition of water leads to the highest TOFmax value (ca. 320 000 s−1) ever reported for a manganese‐based catalyst. A MnI tetracarbonyl intermediate was detected under catalytic conditions for the first time.
What inspired you for the cover design?The image shows aP ortuguese caravel as as ymbol of the Portuguesed iscoveries in the Renaissance,h ighlighting the fact that this Special Issue is dedicated to the "Portuguese Conference on Catalysis". The unexpected flourishing of manganese as ac atalyst reminded us of the tale of the black swan. We have also included an image of the catalytic transformation of ak etone into the corresponding alcoholm ediated by am anganese-basedc atalyst, represented by the black swan.
The first reduction of sulfoxides catalysed by a well‐defined manganese complex is described. A variety of sulfoxides are reduced to the corresponding sulfides in high yields using phenylsilane, diphenylsilane, and the economically feasible 1,1,3,3‐tetramethyldisiloxane (TMDS) as reducing agents in the presence of a Mn‐NHC complex. The reaction is performed under air and without the need of any additive. The involvement of radicals in the catalytic reaction is probed by spin‐trap experiments.
We report here the first purely organometallic fac-[Mn I (CO) 3 (bis-Me NHC)Br] complex with unprecedented activity for the selective electrocatalytic reduction of CO 2 to CO,e xceeding 100 turnovers with excellent faradaic yields (h CO % 95 %) in anhydrous CH 3 CN.U nder the same conditions,amaximum turnover frequency (TOF max )of2100 s À1 was measured by cyclic voltammetry,w hichc learly exceeds the values reported for other manganese-based catalysts.M oreover,t he addition of water leads to the highest TOF max value (ca. 320 000 s À1 )ever reported for amanganese-based catalyst. AMn I tetracarbonyl intermediate was detected under catalytic conditions for the first time.
The electrochemical oxidation of oxalic and oxamic acids on multiwalled carbon nanotubes (CNT) and on monometallic (Pd and Pt) and bimetallic (Pd-Cu, Pt-Cu) catalysts supported on multiwalled carbon nanotubes was investigated using cyclic voltammetry. The electrodes were prepared by dispersion of the catalytic material on Toray carbon (CT) using a Nafion/water solution. The kinetic parameters of the reactions were determined using cyclic voltammetry. Modification of Toray carbon electrode with carbon nanotubes enables the oxidation of oxalic and oxamic acids in the solvent stability region. The highest oxidation current densities were observed for the Pt-Cu/CNT/CT electrode in 0.1 M NaCl. The oxidation potentials for both oxalic and oxamic acids in this case were lower than those observed with the CNT/CT electrode.The prepared electrocatalysts show good mechanical and chemical stability.
Chelating bis-N-heterocyclic carbene (bis-NHC) complexes of iron(ii) containing pyridyl ligands have been prepared by the reaction of [FeCl2L] [L = bipy (1), phen (2)] with [LiN(SiMe3)2] and a bis(imidazolium) salt. The [Fe(bis-NHC)L(I)2] complexes were active pre-catalysts in the oxidation of 1-phenylethanol with tert-butyl hydroperoxide in neat conditions, affording a quantitative yield of acetophenone in 4.5 h. The catalyst could be reused up to six cycles giving a turnover number (TON) of 1500. Various secondary alcohols, both aromatic and aliphatic were selectivity oxidised to the corresponding ketones in excellent yields. Compound 1 is stable in acetonitrile solution for ca. 4 h, although after 16 h, it evolves to a mixture of [Fe(bis-NHC)(bipy)2]I2 (3), [Fe(bipy)3](2+) and bis-imidazolium salt. The molecular structure of 3 has been determined by X-ray diffraction studies.
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