On the Immobilisation of Catechol Phosphane Palladium Complexes on Titania

Chikkali, Samir H.; Gudat, Dietrich; Mallissery, Samith Komath

doi:10.1002/ejic.200800743

Cited by 4 publications

(1 citation statement)

References 20 publications

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“…Herein, we describe the formation of rhodium(I)‐modified NDs (NDs–Rh) using a surface‐immobilized catechol phosphane ligand ( 1 ). While the catechol part provides immobilization of the ligand via interaction with the hydroxyl groups of oxidized NDs, the phosphane functions will coordinate to transition metal centers and form surface‐bound molecular complexes . The catalytic efficiency of the ND–Rh particles was investigated for the alkene hydrogenation as model reaction.…”

Section: Introductionmentioning

confidence: 99%

Wilkinson‐Type Immobilized Catalyst on Diamond Nanoparticles for Alkene Reduction

et al. 2017

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The immobilization of heterogeneous catalysts on solid support materials is an important task of current catalytic and materials science research. We report here the development of a diamond nanoparticles‐based Wilkinson's type catalyst for the reduction of olefins to saturated hydrocarbons. The strategy is based on the formation of rhodium(I)‐modified nanodiamonds (NDs–Rh) using a surface‐immobilized catechol phosphane ligand, to which rhodium metal centers can be coordinated. The resulting material was characterized by solid‐state NMR spectroscopy, X‐ray photoelectron spectroscopy, thermogravimetry, and TEM before testing the catalytic efficiency of the catalyst. Excellent hydrogenation efficiency with yields in the range of 85–99 % could be obtained with these new NDs–Rh catalysts, which showed in addition good recyclability without loss of activity.

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Section: Introductionmentioning

confidence: 99%

Wilkinson‐Type Immobilized Catalyst on Diamond Nanoparticles for Alkene Reduction

et al. 2017

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Bis(acetylacetonato)ruthenium Complexes of Noninnocent 1,2‐Dioxolene Ligands: Qualitatively Different Bonding in Relation to Monoimino and Diimino Analogues

Das

Sarkar

Kumbhakar

et al. 2011

Chemistry A European J

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Coordination compounds [Ru(acac)(2)(Q)] (acac=acetylacetonate; Q=o-benzoquinone) were prepared as complexes 1 (Q=o-benzoquinone), 2 (Q=3-methoxy-o-benzoquinone), 3 (Q=4-methyl-o-benzoquinone), and 4 (Q=3,5-di-tert-butyl-o-benzoquinone). The structures of 1 and 2 were determined to reveal a Ru(III)/o-benzosemiquinone formulation, supported by analysis of experimental data (spectroscopy, magnetism of 1) and by DFT calculations. The S=1 ground state calculated for 1 stands in contrast to the spin-paired analogues with arylimino-o-benzosemiquinonato and diimino-o-benzoquinone ligands. The close contacts of about 5.3 Å possible between semiquinone O atoms of different molecules in the crystal allow for intermolecular spin-spin interactions and an overall complex magnetic behavior. One quasireversible oxidation and two reversible one-electron reductions yielded the corresponding molecular ions, which were characterized by UV-visible-NIR and EPR spectroelectrochemistry in terms of [Ru(III)(acac)(2)(Q(0))](+) , [Ru(III)(acac)(2)(Q(2-))](-), and [Ru(II)(acac)(2)(Q(2-))](2-) descriptions in agreement with DFT results. The use of acceptor-substituted 1,2-dioxolenes resulted in the isolation of ionic species Na[Ru(acac)(2)(Q)] (Na(5); Q=4-chloro-o-benzoquinone) and Na(6) (Q=4-nitro-o-benzoquinone), which were similarly investigated as compounds 1-4. Magnetic susceptibility and EPR results confirm an S=1/2 ground state based on ruthenium(III). The combined studies reveal a remarkable substituent sensitivity, and in comparison to recently analyzed Ru(acac)(2) complexes with o-benzoquinone monoimine and diimine ligands, the all-O-donor-containing new systems are distinguished by a qualitatively different metal-ligand interaction based on closer intermolecular radical-radical contacts and on weaker intramolecular dπ-π* interactions.

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Ruthenium Catechol Phosphane Complexes as Metalloligands for the Controlled Assembly of Heterobimetallics

et al. 2017

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Highly specific reactions of a catechol phosphane (2, H 2 L) with suitable ruthenium precursors afforded complexes [Ru(LH 2 ) 2 Cl 2 ], [Ru(LH) 2 (L′) x ] (L′ = NO, PPh 3 , Cl, py, CNtBu) or [Ru(LH) 3 ]Y (Y = H, K), in which 2 acts as P,O-bound chelating ligand. The formation of bis-or tris-chelate structures depends on the metal-to-ligand ratio employed. All products were characterized by analytical and spectroscopic data and single-crystal XRD studies. The orientation of the neutral and mono-deprotonated catechol groups is strongly influenced by hydrogen bonding, and the free hydroxyl groups in some complexes are [a] 3834 pre-organized for coordination of a second metal centre, and this suggests that these species can be used as metalloligands. This hypothesis was verified by the synthesis of heterobimetallic Ru,Ti complexes through reactions of selected metalloligands with suitable Ti IV precursors. Characterization of the products by single-crystal XRD studies revealed that the bimetallic complexes contain cores of two face-sharing metalcentred octahedra, which are linked by two and three ditopic ligands, respectively. accessed in one step through self-assembly of the hybrid phosphane and suitable Lewis acids, or by a two-step sequence. In this case, the ditopic ligand is first allowed to react with a single metal centre with a strong preference for one of the two binding sites. As the second site is still available, the resulting complex can be viewed as a metalloligand [6] that may subsequently coordinate a second metal ion to yield the final product. Depending on the nature of the initial reactant, hybrid phosphanes can give rise to metalloligands that offer either their phosphorus atom or the complementary functional groups for further coordination.A specific illustration of this concept is given by catechol phosphanes such as 1 [7] or 2 [8] (Scheme 1), which were used as Scheme 1. Ditopic catechol phosphanes 1, 2 and selected transition metal complexes.

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On the Immobilisation of Catechol Phosphane Palladium Complexes on Titania

Cited by 4 publications

References 20 publications

Wilkinson‐Type Immobilized Catalyst on Diamond Nanoparticles for Alkene Reduction

Wilkinson‐Type Immobilized Catalyst on Diamond Nanoparticles for Alkene Reduction

Bis(acetylacetonato)ruthenium Complexes of Noninnocent 1,2‐Dioxolene Ligands: Qualitatively Different Bonding in Relation to Monoimino and Diimino Analogues

Ruthenium Catechol Phosphane Complexes as Metalloligands for the Controlled Assembly of Heterobimetallics

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