Surface-mediated organometallic synthesis: preparation of osmium carbonyl clusters [Os5C(CO)14]2- and [Os10C(CO)24]2- on the basic magnesium oxide surface

Abstract

High-nuclearity osmium carbonyl clusters have been synthesized by simple means and in high yields on the surface of porous, high surface area magnesium oxide in the presence of CO and CO + H2. Control of the product distributions was exerted by choice of the temperature, pressure, gas-phase composition, and metal compound precursor. [Os10C(CO)24]2™ was prepared from [H20sCl6] adsorbed on MgO treated in equimolar CO + H2 at 275 °C and 1 atm, and [Os5C(CO)14]2™ was prepared from [Os3(CO)12] adsorbed on MgO treated in CO at 275 °C and 1 atm. These cluster anions were isolated from the MgO in 65% yield by cation metathesis with [PPN] [Cl] in acetone. These syntheses are more efficient than the best known solution syntheses; the results suggest a more general applicability of surface-mediated synthesis.

Triosmium Clusters on a Support: Determination of Structure by X‐ray Absorption Spectroscopy and High‐Resolution Microscopy

“…n-Pentane solvent (Aldrich) was refluxed under N 2 in the presence of sodium/benzophenone ketyl to remove traces of water and Synthesis of supported triosmium carbonyl clusters: The MgO-supported samples were prepared, as before, [29] by slurrying [Os 3 (CO) 12 ] with the calcined MgO powder in n-pentane under N 2 for 24 h at room temperature followed by overnight evacuation at 298 K to remove the solvent. A calculated amount of [Os 3 (CO) 12 ] was added to the MgO support to give samples containing 1.0 wt % Os when all the added osmium remained on the support, [33] and the synthesis method assured that it did.…”

“…12 ] has been used before as a precursor of oxidesupported metal clusters. [2,28,29,33,44,45] The structures of supported metal clusters synthesized from [Os 3 (CO) 12 ] have been characterized by IR, [28,29] Raman, [46] and EXAFS spectroscopies and TEM. [29] Various supports have been used for these samples, and often the cluster frame has evidently remained essentially intact.…”

Supported Metal Cluster Catalysts

“…For example, surface-mediated synthesis was used to convert Os 3 (CO) 12 into [Os 5 C(CO) 14 ] 2− on MgO [6,7,9], and comparable chemistry occurs in basic solutions. For example, surface-mediated synthesis was used to convert Os 3 (CO) 12 into [Os 5 C(CO) 14 ] 2− on MgO [6,7,9], and comparable chemistry occurs in basic solutions.…”

“…The large majority of research data obtained during the 1980s and early 1990s has been published in several reviews [1][2][3][4][5][6][7][8]. The large majority of research data obtained during the 1980s and early 1990s has been published in several reviews [1][2][3][4][5][6][7][8].…”

Volcano relationships in metal cluster catalysis: An infrared spectroscopic monitor of site character

“…The catalytically active cluster was a complex entity. During thermal activation, not only was a small proportion of the carbonyl ligands lost, evolved as gaseous CO, but a further small proportion underwent reaction generating carbon dioxide and leaving ligand-C associated with the catalyst (Boudouard reaction) [3,6,9,[12][13][14].…”