Novel Phosphinite−Ruthenium(II) Complexes Covalently Bound on Silica: Synthesis, Characterization, and Catalytic Behavior versus Oxidation Reactions of Alcohols into Aldehydes

Abstract

The novel tridentate phosphinite−Ru complex 5 has been prepared, characterized, and bound on silica via the spacer arm 16. The efficiency of this heterogenized catalyst for the oxidation of alcohols into aldehydes with N-methylmorpholine oxide has been examined, in comparison to the efficiency of the corresponding heterogenized monodentate phosphinite−Ru complex (without 7 and with the spacer arm 11) and the corresponding homogeneous catalysts 3 and 5, respectively. The heterogenized monodentate catalysts were 2 and 3 times more active than the soluble phosphinite−Ru complex, while the heterogenized tridentate catalyst showed almost the same activity. All catalysts are endowed with good to excellent selectivities. The heterogenized monodentate catalysts could not be efficiently recycled; on the other hand, the heterogenized tridentate catalyst 16 worked for four cycles. However, the major problem was a significant metal leaching, after the first cycle.

Self‐Assembly of Supramolecular Architectures and Polymers by Orthogonal Metal Complexation and Hydrogen‐Bonding Motifs

“…4'-(2-Furyl)-2,2':6',2''-terpyridine was obtained from 2-acetylpyridine and 2-furaldehyde as described by Constable et al [35] Oxidation by KMnO 4 [36] leads to 2,2':6',2''-terpyridine-4'-carboxylic acid (2). 5-Amino-N,N'-bis[6-(3,3-dimethylbutyrylamino)pyridin-2-yl]isophthalamide [5] (Hamilton amine 3), 6-aminohexanoic acid methyl ester hydrochloride (4), [37] diethyl 2,5-didodecyloxyterephthalate (11), [20,21] 2,5-didodecyloxyterephthalic acid (12), [20,21] [RuA C H T U N G T R E N N U N G (DMSO) 4 ]Cl 2 , [23] and [PtA C H T U N G T R E N N U N G (DMSO) 2 Cl 2 ] [38] were prepared as described in the literature; syntheses of 1-(6-hydroxyhexyl)-1,3,5-triazine-2,4,6-trione) (13) [19] and di-tert-butyl 4-(3-tert-butoxy-3-oxopropyl)-4-[6-(2,4,6-trioxo-1,3,5-triazinan-1-yl)hexanamido]heptanedioate (8) [12] were previously reported by us. HPLC was performed with Varian 940-LC and a Nucleodur 100 (5 mm, C18 end capped) column by Macherey-Nagel.…”

“…[12] We used RuCl 3 ·x H 2 O (in the presence of MeOH, EtOH, or 4-ethylmorpholine as reducing agent) and [RuA C H T U N G T R E N N U N G (DMSO) 4 ]Cl 2 [23] as sources of Ru II . Additionally, AgPF 6 was added to the reaction mixture to provide the PF 6 À counterion.…”

Chemical, Electrochemical, and Photochemical Catalytic Oxidation of Water to Dioxygen with Mononuclear Ruthenium Complexes

“…[Ru(Cl) 2 (DMSO) 4 ] [30] and the H3p [31] , were prepared via a previously published procedure. [16] All synthetic manipulations were performed under an argon atmosphere by using Schlenck techniques.…”

Novel silica immobilized NCN-pincer palladium(II) and platinum(II) complexes: Application as Lewis acid catalysts

“…The properties of silica include thermal and chemical stability under reaction conditions, easily accessible and well-dispersed surface active sites (a high surface area >100 m 2 g −1 is required), and a mesoporous structure which is a prerequisite for liquid phase processes (pore size >20Å to avoid diffusion limitations) [17]. A wide range of homogeneous catalysts has been immobilized on silica and successfully recycled [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33].…”