- Accelerated photorelease of NO from {Ru-NO}6 nitrosyls containing carboxamido-N and carboxylato-O donors: Syntheses, structures, and photochemistry
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Three ruthenium nitrosyls, namely, [(Me2bpb)Ru(NO)(OAc)], [(Me2bpb)Ru(NO)(OBz)] (1), and [(Me2Qb)Ru-(NO)(qca)] (BF4) (2), have been synthesized from designed ligands with carboxamido-N donors. In all three compl
- Halpenny, Genevieve M.,Mascharak, Pradip K.
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- Ruthenium(0) nanoclusters stabilized by a nanozeolite framework: Isolable, reusable, and green catalyst for the hydrogenation of neat aromatics under mild conditions with the unprecedented catalytic activity and lifetime
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The hydrogenation of aromatics is a ubiquitous chemical transformation used in both the petrochemical and specialty industry and is important for the generation of clean diesel fuels. Reported herein is the discovery of a superior heterogeneous catalyst, superior in terms of catalytic activity, selectivity, and lifetime in the hydrogenation of aromatics in the solvent-free system under mild conditions (at 25 °C and 42 ± 1 psig initial H2 pressure). Ruthenium(0) nanoclusters stabilized by a nanozeolite framework as a new catalytic material is reproducibly prepared from the borohydride reduction of a colloidal solution of ruthenium(III)-exchanged nanozeolites at room temperature and characterized by using ICP-OES, XRD, XPS, DLS, TEM, HRTEM, TEM/EDX, mid-IR, far-IR, and Raman spectroscopy. The resultant ruthenium(0) nanoclusters hydrogenate neat benzene to cyclohexane with 100% conversion under mild conditions (at 25 °C and 42 ± 1 psig initial H2 pressure) with record catalytic activity (initial TOF = 5430 h-1) and lifetime (TTO = 177 200). They provide exceptional catalytic activity not only in the hydrogenation of neat benzene but also in the solvent-free hydrogenation of methyl substituted aromatics such as toluene, o-xylene, and mesitylene under otherwise identical conditions. Moreover, they are an isolable, bottleable, and reusable catalyst in the hydrogenation of neat aromatics. When the isolated ruthenium(0) nanoclusters are reused, they retain 92% of their initial catalytic activity even for the third run in the hydrogenation of neat benzene under the same conditions as those of the first run. The work reported here also includes (i) far-infrared spectroscopic investigation of nanozeolite, ruthenium(III)-exchanged-nanozeolite, and ruthenium(0) nanoclusters stabilized by a nanozeolite framework, indicating that the host framework remains intact after the formation of a nanozeolite framework stabilized ruthenium(0) nanoclusters; (ii) the poisoning experiments performed by using tricyclohexylphosphine (P(C6H11)3) and 4-ethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane PC6H 11O3 to examine whether the ruthenium(0) nanoclusters are encapsulated in the cages or supported on the external surface of nanozeolite; (iii) a summary section detailing the main findings for the green chemistry ; and (iv) a review of the extensive literature of benzene hydrogenation, which is also tabulated as part of the Supporting Information.
- Zahmakiran, Mehmet,Tonbul, Yalcin,Oezkar, Saim
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- Synthesis and characterisation of some Ru(II) complexes of 2-carbamoylpyridine derivatives
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p-Substituted N-phenyl derivatives of 2-carbamoylpyridine (L) have been prepared by the reaction of pyridine-2-carboxylic acid with p-substituted aniline. Five complexes of the type [Ru(L)(DMSO)2Cl2] have been synthesized by the reaction of [Ru(DMSO)4Cl2] with L. The amide ligands have been characterized by elemental analysis, infra red and 1H NMR spectral studies. The complexes are diamagnetic and show intense absorptions due to metal to ligand charge transfer (MLCT) transitions in the UV-visible spectra. The IR spectra of the complexes show that the amide ligands coordinate to the ruthenium (II) ion as a bidentate ligand coordinating from pyridyl nitrogen and from the carbonyl oxygen of the amide group. The complexes undergo a reversible ruthenium (II)-ruthenium (III) oxidation near 0.55 V in acetonitrile solution. The ruthenium (II)-ruthenium (III) oxidation potentials of the complexes are found to be sensitive to the nature of the substituent on the ligand. Elsevier Science Ltd.
- Dutta, Sujit,Pal, Sarbani,Bhattacharya, Pabitra K.
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p. 2157 - 2162
(2008/10/09)
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