89654-69-3Relevant academic research and scientific papers
Convenient synthesis and molecular structure of PPN[RhCl 2(CO)2] (PPN+ = Bis(triphenylphosphane)iminium)
Boettcher, Hans-Christian,Mayer, Peter
, p. 376 - 378 (2014)
The reaction of hydrated rhodium(III) chloride with formic acid in refluxing ethoxyethanol afforded in a convenient way the known rhodium carbonyl chlorido complex anion cis-[RhCl2(CO)2]-. This species was formed in good yield and was characterized as its PPN salt (PPN + = bis(triphenylphosphane)iminium cation). The molecular structure of the title compound PPN[RhCl2(CO)2] was confirmed by X-ray diffraction and shown to be isomorphous to PPN[IrCl2(CO) 2].
The ketenylidene route to mixed-metal carbide clusters: -, -, 2-, 2-, -, 2- and -
Jensen, Michael P.,Henderson, William,Johnston, Dean H.,Sabat, Michal,Shriver, Duward F.
, p. 121 - 143 (1990)
Redox-condensation reactions between the ketenylidene clusters 2- (M = Ru, Os) and electrophilic transition-metal reagents provide a convenient route to the new carbido clusters , -, 2, 2(Mo2Ru3C(CO)16>, , 2 and .These clusters have been characterized by elemental analysis, IR and variable-temperature 13C NMR spectroscopy, and, in the case of and 2 by single-crystal X-ray diffraction studies.The - cluster consists of a butterfly array of metal atoms with the manganese occupying a hinge position.The structure of the 2- is a distorted (opened) octahedron of metal atoms, with the three rhutenium atoms forming one closed face of the octahedron, and the carbide ligand occupying an interstitial site. 13C NMR data indicate the octahedron closes in solution.For and , the carbide ligands show variable temperature NMR behavior, which is best interpreted in terms of a two-bond spin-spin coupling of the carbide to the two endo carbonyls on the wingtip Ru or Os atoms.A similar two-bond coupling process may possibly also be operating in the 2- cluster.
Hydroformylation of formaldehyde with the [Rh(CO)2Cl2]- and [Rh5(CO)15-x(PPh3)x]- system: A case of synergetic catalysis with two combined rhodium carbonyl species in different oxidation states
Marchionna, Mario,Longoni, Giuliano
, p. 606 - 610 (1987)
Paraformaldehyde has been hydroformylated to glycolaldehyde at 100-140 atm of CO and H2 (1/1) and at 90-110°C with selectivity up to 95% in common organic solvents, e.g., acetone, with a catalytic system involving two preformed anionic rhodium carbonyl species in different formal oxidation states, viz., [Rh(CO)2Cl2]- and [Rh5(CO)15-x(PPh3)x]-. This system combines the high activity of the latter with the high selectivity of the former and enables the hydroformylation of paraformaldehyde to be carried out at a rate comparable with that previously observed only in N,N-disubstituted amide or pyridine solvents. A strictly related system, generated in situ upon addition of halide ions and triphenylphosphine to Rh4(CO)12, showed comparable catalytic behavior. A temptative interpretation of the synergetic effect shown by mixtures of [Rh(CO)2Cl2]- and [Rh5(CO)15-x(PPh3)x]- is suggested.
Promotion of the [PPN][Rh(CO)4]-catalysed carbonylation of nitrobenzene by 2-hydroxypyridine and related molecules: An apparent bifunctional activation
Ragaini, Fabio,Gallo, Emma,Cenini, Sergio
, p. 109 - 118 (2007/10/03)
2-Hydroxypyridine and related molecules have a large activating effect on the previously reported [PPN][Rh(CO)4]-based catalytic system for the reductive carbonylation of nitrobenzene to methyl phenylcarbamate (PPN+=(PPh3)2N+). The effect is not due to the known 2-hydroxypyridine-2-pyridone tautomeric equilibrium, since 4-hydroxypyridine, for which the same tautomeric equilibrium exists, completely inhibits the reaction. A promoting effect of 2-hydroxypyridine is also observed in the reactions of a previously isolated metallacyclic complex, [PPN][Rh(CO)2ON(Ar)C(O)O], believed to be an intermediate in the catalytic reactions. However, the dependence of the rate of the catalytic reactions on the aniline concentration indicates that the effect found for the stoichiometric reaction cannot be the one that is relevant for the acceleration of the catalytic reactions. Thus, two different effects are present, both of which appear to be due to the proximal positions of a basic and an acidic site in the promoter molecules.
Mechanistic study of the carbonylation of nitrobenzene catalyzed by the [Rh(CO)4]-/nitrogen base system. X-ray structure of [PPN][Rh(CO)2ON(C6H3Cl2)C(O)O]
Ragaini, Fabio,Cenini, Sergio,Demartin, Francesco
, p. 1178 - 1189 (2008/10/08)
[PPN][Rh(CO)4] (1) reacts with ArNO2 or ArNO to yield the same product (Ar = Ph, 2; Ar = 3,4-Cl2-C6H3, 3). The reaction of 1 with nitrosoarenes also produces the corresponding azoxyarenes. The product was structurally characterized in the case of Ar = 3,4-dichlorophenyl and was shown to be [PPN][Rh(CO)2ON(C6H3Cl2)C(O)O] (3). Crystal data for 3: C45H33-Cl2N2O5P 2Rh·C4H8O, Mr = 989.64, triclinic, space group P1 (No. 2), a = 10.798(4) A?, b = 9.889(6) A?, c = 21.648(6) A?, α = 89.77(1)°, β = 96.00(1)°, γ = 92.71(1)°, V = 2296(2) A?2, Z = 2, Dc = 1.431 g cm-3, Mo Kα radiation (λ = 0.710 73 A?), μ(Mo Kα) = 6.00 cm-1, R = 0.037 (Rw = 0.047) for 5299 independent reflections having I > 3σ(I). Both of the reactions proceed through electron transfer to the nitroso or nitro derivative. Reaction of 2 and 3 with MeOH and CO produced the corresponding amine or the methyl carbamate, depending on the experimental conditions. The reaction of 3 with MeOH/CO was faster in the presence of nitrogen bases, and aniline was shown to be an intermediate in the synthesis of the carbamate. When the same reaction was performed in the presence of a large excess of nitrosobenzene, the two isomeric mixed azoxybenzenes 3,4-Cl2-C6H3N(O)=NPh and 3,4-Cl2-C6H3N=N(O)Ph were the largely dominant products, which strongly suggests the intermediate formation of a nitrene complex.
Reactivity of Rh4(CO)12 with halides or pseudohalides: Synthesis of the pentanuclear carbonyl clusters [Rh5(CO)14X]n- (X = Cl, Br, I, SCN, n = 2; X = PPh3, n = 1). Crystal structures of [N(PPh3)2][Rh5(μ-CO)6(CO) 8(PPh3)] and ...
Fumagalli, Alessandro,Martinengo, Secondo,Galli, Daniele,Allevi, Claudio,Ciani, Gianfranco,Sironi, Angelo
, p. 1408 - 1413 (2008/10/08)
Full title: Reactivity of Rh4(CO)12 with halides or pseudohalides: Synthesis of the pentanuclear carbonyl clusters [Rh5(CO)14X]n- (X = Cl, Br, I, SCN, n = 2; X = PPh3, n = 1). Crystal structures of [N(PPh3)2][Rh5(μ-CO)6(CO) 8(PPh3)] and [N(PPh3)2]2[Rh5(μ-CO) 6(CO)8(SCN)]. The reaction of Rh4(CO)12 with salts of [X]- (X = Cl, Br, I, SCN) under CO yields salts of the dianionic species [Rh5(CO)14X]2-. These can also be produced, together with salts of [Rh5(CO)14(PPh3)]-, by nucleophilic substitution on salts of the anionic substrate [Rh5(CO)15]-. All of these 76 cluster valence electron derivatives are stable under 1 atm of CO but decompose under nitrogen or in a vacuum. the X-ray structural analysis of the [PPN]+, (μ-nitrido)bis(triphenylphosphorus)(1+), salts of [Rh5(CO)14(PPh3)]-(1) and [Rh5(CO)14(SCN)]2- (II), revealed in both anions an elongated trigonal-bipyramidal metallic frame, with eight terminal and six edge-bridging carbonyls; the entering group is bond to an apical rhodium. Crystal data for I: C68H45NO14P3Rh5, fw = 1707.6, monoclinic, P21/c (No. 14), a = 21.707 (4) A?, b = 17.054 (2) A?, c = 19.815 (4) A?, β = 114.67 (2)°, Z = 4, final R = 0.041, Rw = 0.050. Crystal data for II: C87H60N3O14P4Rh 5S, fw = 2041.9, monoclinic, P21/c (No. 14), a = 25.877 (6) A?, b = 15.115 (3) A?, c = 22.776 (6) A?, β = 93.95 (2)°, Z = 4, final R = 0.069, Rw = 0.092.
Syntheses of reactive mixed-metal carbide clusters and their interaction with proton sources
Hriljac, Joseph A.,Swepston, Paul N.,Shriver, Duward F.
, p. 158 - 166 (2008/10/08)
The three-iron ketenylidene [Fe3(CO)9(CCO)]2-, I, undergoes a redox condensation reaction with [Rh-(CO)2Cl]2 to produce a reactive butterfly carbide [RhFe3(CO)12C]-, VIII. Similarly, I in the prescence of [Mn(CO)5(CH3CN)]+ leads to [MnFe3(CO)13C]-, IX. Both products were characterized by 13C NMR spectroscopy, and the structure of the rhodium cluster VIII was determined by single-crystal X-ray diffraction. Monoprotonation of VIII and IX yields the butterfly methylidynes RhFe3(CO)12(CH), XII, and MnFe3-(CO)13(CH), XIII. This site of protonation contrasts with the butterfly carbide [Fe4(CO)12C]2-, II, which first protonates on the metal framework. In some cases the redox condensation reaction does not terminate at the four-metal butterfly cluster stage, thus the reaction of I with [CpNi(CO)]2 yields [Ni3Fe3(CO)13C]2-, X. Attempts to generate a butterfly carbide via a metal substitution pathway employing II and Co2(CO)8 did not lead to a tetranuclear cluster but produced instead the pentanuclear carbide [CoFe4(CO)14C]-, XI, the structure of which was also determined by single-crystal X-ray diffraction. X-ray crystal data for [PPN][RhFe3(CO)12C]·CH2Cl2, VIII: orthorhombic, a = 17.780 (2) A?, b = 19.641 (4) A?, c = 15.145 (4) A?, Z = 4, space group Pna21. For [PPN][CoFe4(CO)14C], XI: monoclinic, a = 17.403 (3) A?, b = 16.030 (3) A?, c = 19.055 (2) A?, β= 105.34 (1)°, Z = 4, space group P21/n.
Synthesis and Chemical Characterization of the New Anions -(E=S or Se). Crystal and Molecular Structures of and
Galli, Daniele,Garlaschelli, Luigi,Ciani, Gianfranco,Fumagalli, Alessandro,Martinengo, Secondo,Sironi, Angelo
, p. 55 - 62 (2007/10/02)
Reactions of or in tetrahydrofuran with -, -, or with polysulphides give, together with the decanuclear clusters 2-, the trinuclear anions - (E=S or Se).The latter species have been isolated and investigated by X-ray analysis.The salt (1) crystallizes in the orthorhombic space group Pbc21 (no.29) with a=13.529(2), b=16.965(2), c=28.365(6) Angstroem, and Z=8; (2) crystallizes in the orthorhombic space group Ccm21 (no.36) with a=14.029(2), b=10.889(2), c=12.748(2) Angstroem, and Z=4.Both structures were solved by conventional Patterson and Fourier methods and refined on the basis of 3 438 and 1 032 significant independent counter data, respectively, to final conventional R values of 0.042 for compound (1) and 0.026 for (2).Both anions consist of a Rh3 triangle bicapped by triply bridging chalcogenide atoms and each rhodium atom, bearing two terminal CO groups, displays an almost square-planar geometry.The Rh-Rh distances are long and suggest very weak, if any, metal-metal interaction.The two anions can therefore be considered as trinuclear rhodium(I) aggregates rather than triangular clusters.
