Prominent hydrogenation catalysis of a PVP-stabilized Au34 superatom provided by doping a single Rh atom

A single rhodium atom was precisely doped into a gold cluster Au34 stabilized by poly(N-vinyl-2-pyrrolidone) (Au:PVP) as revealed by mass spectrometry.

Pyrene-tagged carbohydrate-based mixed P/S ligand: spacer effect on the Rh(i)-catalyzed hydrogenation of methyl α-acetamidocinnamate

The chain length between the pyrene group and the rhodium atom in mixed P/S catalysts is crucial in the enantioselective hydrogenation of enamides, and the most active catalyst can be used in catch and release process.

AN EVALUATION OF QUANTUM CHEMICAL CALCULATIONS OF REACTION ENERGIES FOR CATALYTIC ACTIVATION PROCESSES: THE ACTIVATION OF PROPANE BY A RHODIUM CATALYST REVISITED

In this paper we report the state of the art CCSD(T)//MP2 ab initio calculations for the activation of propane by cyclopentadienyl carbonyl rhodium, (Cp)Rh(CO) , using the effective core potential of Hay and Wadt (LANL2DZ) for rhodium atom and the correlated consistent polarized valence double-ξ basis set (cc-pVDZ) for C , H and O atoms. The CCSD(T) energy values are used as reference to assess the effect of electron correlation on the reaction energies, as well as the performance of density functional theory (DFT) energy values using various functionals. An investigation on the accuracy of DFT results is relevant since their use in calculations involving large molecular systems is a computationally efficient strategy that enables us to tackle important problems in organometallics field and supramolecular chemistry. Our results for the small model system show that all DFT functionals used here correctly predict the CCSD(T) energy pattern and also reproduce very satisfactorily the MP2 geometrical parameters. The BP86, PBE1PBE and PW91 functionals exhibited the best agreement with structural parameters and relative energy values as compared with ab initio post-Hartree–Fock results, showing a potential use in theoretical investigations on larger systems.

Competition of Ester, Amide, Ether, Carbonate, Alcohol and Epoxide Ligands in the Dirhodium Experiment (Chiral Discrimination by NMR Spectroscopy) [1]

Thirty-eight derivatives of 3-hydroxy-2-methylpropanoic acid, each with two different oxygen functionalities, were synthesized and subjected to the standard dirhodium experiment (1H NMR in the presence of an equimolar amount of the chiral dirhodium tetracarboxylate complex Rh*). Their structures represent ester, amide, carbonate, ether, alcohol and/or epoxy groups. Significant selectivity in the binding of those oxygen groups to the complex were determined. From these results, a priority list in binding to a rhodium atom of Rh* was established: epoxides > primary alcohols > ethers ≥ esters ≥ amides > carbonates > tertiary alcohols This sequence allows the prediction of the preferred binding site of oxygen-containing groups in polyfunctional compounds, which frequently occur among natural products, and, particularly, in asymmetric synthesis of such compounds. Differentiation of the enantiomers by the dirhodium experiment is easily accomplished due to numerous signal dispersions in nearly all cases.

Structural Characterization Of Rh(Iii) Complexes Containing The Polypyridyl Ligands And Some Properties Of Their Derivatives

The structures of the compounds [Rh(bpy)2(py)(Cl)](ClO4 )2 (2 (ClO4 )2) and [Rh(phen)2(py)- (Cl)](ClO4 )2 (7 -(ClO4 )2) were determined by single-crystal X-ray diffraction. Both complexes show a six-coordinate rhodium atom with two bpy or phen ligands in the cis configuration. The Rh-Cl distances are 2.334(3) and 2.323(2) Å, respectively. The bond angles N-Rh-Cl formed with the axially-positioned nitrogen atom are 174.4(2) and 173.8(2)°. The oxidation of aquo complexes, prepared from the corresponding rhodium chloride complexes, by two equivalents of Ce(IV) in 60% HCIO4 solution yields the corresponding mono-oxo products. All complexes have been identified and characterized by elemental analyses, IR, and 1H NMR data

N,S-Chelating Amino-ortho-carboranethiolate Complexes of Rhodium and Iridium: Synthesis and Reactivity. X-Ray Crystal Structures of (η4-C8H12)Rh[(NMe2CH2)SC2B10H10] and (CO)2Rh[(NMe2CH2)SC2B10H10]

The reaction of [M(μ-Cl)(cod)]2 (M = Rh, Ir; cod = cycloocta-1,5-diene) with two equivalents of the lithium ortho-carboranethiolate derivative LiCabN,S 2 [LiCabN,S = closo-2-(dimethylaminomethyl)-1-(lithiumthiolato)-ortho-carborane] produced the four-coordinated metallacyclic compounds, CabN,SM(cod) 3 (M = Rh 3a, Ir 3b), in which the metal atom was stabilized via intramolecular N,S-coordination. These new compounds have been isolated in high yields and characterized by IR and NMR spectroscopy. The structure consists of an amino-ortho-carboranethiolate fragment bonded to (cod)Rh(I) via nitrogen and sulfur, so as to give the metal a square-planar environment. Subsequent carbonylation reactions of 3a, 3b result in the quantitative formation of the corresponding (amino-ortho-carboranethiolato)(carbonyl)metal N,S-chelates CabN,SM(CO)2 4 (M = Rh 4a, Ir 4b). The metal carbonyl complexes 4a, 4b have been isolated and characterized by spectroscopic and compound 4a also by X-ray diffraction techniques. The molecular structure of 4a reveals that the rhodium atom is coordinated by nitrogen and sulfur atoms of the amino-ortho-carboranethiolate ligand, and two carbonyl ligands complete the coordination of the metal atom.