A More General Approach to Distinguishing "Homogeneous" from "Heterogeneous" Catalysis: Discovery of Polyoxoanion- and Bu4N+-Stabilized, Isolable and Redissolvable, High-Reactivity Ir.apprx.190-450 Nanocluster Catalysts

The water-soluble cluster cation [H3Ru3(C6H6)(C6Me6)2(O)]+: Improved synthesis, aerobic oxidation, electrochemical properties and ligand exchange studies

“…In conclusion, an improved preparation resulting in 51% of pure [1] 4 ] is a novel composition and structure organometallic complex, it is quite stable and relatively unreactive. These findings are consistent with our conclusions elsewhere that trace Ru(0) n nanoclusters are the true benzene hydrogenation catalyst derived from [1][BF 4 ] and not this otherwise interesting organometallic complex itself.…”

“…The resulting clear yellow filtrate was cooled in an ice-bath for 30 min. In a separate 50 mL Schlenk tube, 75 mg (1.974 mmol) of NaBH 4 were dissolved in 15 mL of water at room temperature. After stirring for 5 min, the NaBH 4 solution was transferred very slowly through a cannula into the ice-bath-cooled [Ru(C 6 (210 mg, 0.420 mmol) was added.…”

“…After stirring for one hour at room temperature, the red precipitate was centrifuged in air (1500 rpm, 10 min), the aqueous solution was removed from the centrifuge tube with a glass pipette. The red solid was dissolved in CH 2 Cl 2 and again filtered through filter pulp to eliminate excess NaBF 4 . Then the methylene chloride solution was concentrated to 15 mL in vacuo.…”

“…However, for benzene hydrogenation catalysis derived from organometallic precatalysts the true nature of the catalytic species has remained a debatable point (''is it homogeneous or heterogeneous catalysis?'') [4]. In the case of the putative homogeneous [(C 8 H 17 ) 3 Me]- [RhCl 4 ] ion pair catalyst [5], Finke and co-workers [6] were able to demonstrate that rhodium(0) nanoclusters are the true catalysts (''soluble analogs of heterogeneous catalysts'').…”

“…question for benzene hydrogenation beginning with [1][BF 4 ] [9,10], it proved necessary to develop an improved synthesis for the quantities of 1 that were required, since it is difficult to obtain pure [1][BF 4 ] by crystallization according to the original procedure [1]. In addition, we decided to study the redox properties and the ligand exchange processes of this cluster in detail.…”