Reactivity of the terminal oxo species ((tBu2PCH2SiMe2)2N)RhO

Abstract

Reactivity of the 4-coordinate molecule (PNP)RhO (PNP is ((t)Bu2PCH2SiMe2)2N) towards CO proceeds stepwise, first forming an η(2)-CO2 complex, by a mechanism which involves a preliminary adduct of CO on Rh, then a second CO displaces CO2. Reaction of the oxo complex with CO2 occurs in time of mixing even at low temperature to form (PNP)Rh(η(2)-CO3), with no intermediate detectable. DFT calculations indicate an initial bond formation between the oxo center and the CO2 carbon. Reaction of (PNP)RhO with H2 occurs only at a 1 : 2 molar stoichiometry, to ultimately form (PNP)Rh(H)2 and free H2O. No intermediate reaches detectable population even at -60 °C, but DFT mapping of various possible mechanisms on the singlet energy surface shows that the nearly equi-energetic (PNP)Rh(H2O) and (PNP)RhH(OH) are formed, but only the latter readily adds the second molecule of H2 to proceed to the observed products; these reactions thus both involve heterolytic splitting of H2.

Oxygen radical character in group 11 oxygen fluorides

“…Transition metal complexes bearing terminal oxido (O 2− , oxo) ligands are quite common. Nevertheless, those of the late transition metals are very rare 1 – 8 , and in particular group 11 terminal oxo complexes (M = Cu, Ag, Au) are to our knowledge still elusive 1 , 9 – 12 . On the other side molecular binary group 11 metal oxygen complexes, MO x , have extensively been studied in gas phase and matrix-isolation studies 13 , 14 .…”

Uptake of one and two molecules of CO2 by the molybdate dianion: a soluble, molecular oxide model system for carbon dioxide fixation

“…Metal oxide catalysts for CO 2 transformations are advantageous based on considerations of cost, ease of re-use, and stability, 1 but these advantages come at the expense of our ability to readily characterize such systems at a molecular level of detail. Intrigued by the paucity of soluble transition-metal oxide systems known to react with CO 2 in a well-dened manner (e.g., eqn (1)), [2][3][4] we decided to investigate salts of the molybdate dianion in this respect, in order to determine the behavior and mode of reaction (if any) of a simple oxoanion with carbon dioxide as either the potential basis for a new homogeneous catalytic system or as a soluble model for known heterogeneous oxide catalysts. Accordingly, herein we report the nding that molybdate absorbs not just one but two equivalents of CO 2 (the second, reversibly) together with complete characterization including single-crystal X-ray diffraction studies of the resulting mono-and dicarbonate complexes.…”

Reduction of carbon dioxide and organic carbonyls by hydrosilanes catalysed by the perrhenate anion

“…3,37,[44][45][46][47][48][49][50][51][52][53][54] High oxidation state transition metal oxo complexes 55 have been studied in CO 2 reduction chemistry and have been shown to react to form metal carbonates where, in the case of molybdate, the resulting carbonate undergoes hydrosilylation to formate and silylated molybdate, albeit stoichiometrically. [56][57][58][59] Furthermore, rheniumIJV) mono and dioxo complexes act as catalysts for the hydrosilylation of organic carbonyls, [60][61][62][63][64][65] but this activity is not generally seen for the parent perrhenate, ReO 4…”