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1.
Andrei B. Koudriavtsev Andrei T. Teleshev Aleksei A. Zhdanov Eduard E. Nifant’ev Wolfgang Linert 《Monatshefte für Chemie / Chemical Monthly》2001,52(12):1001-1012
Complexation of Rh(I) with o, o′-dimethylene-(tris-p-cresyl)-bicyclophosphite (BCP, 1) has been investigated in solution by NMR, semi-empirical quantum mechanical, and molecular mechanics calculations. 1H and 31P NMR spectroscopic data show that when the BCP/Rh ratio exceeds 2, Rh hydride complexes of the composition RhH(BCP)3 and RhH(BCP)4 are formed. The source of the hydride ion is the ligand itself; most probably, H− originates from the bridging CH2 groups of BCP. The chemical shifts of these protons are sensitive to complexation due to the considerable electron density of HOMO and LUMO at one of the bridging CH2 moieties. Molecular mechanics simulations of the molecular structure of these complexes show that two cavities are formed in [Rh(BCP)3]+ by the aromatic rings of the ligands. These cavities may alternatively open and close, thus providing for a flexibly shielded catalytic site which explains the unusual catalytic behaviour of Rh complexes with BCP in hydrogenation and hydroformylation reactions. 相似文献
2.
Kudryavtsev A. B. Teleshev A. T. Nifant"ev E. E. Linert W. 《Russian Chemical Bulletin》2003,52(12):2740-2746
A representative of the new class of organophosphorus ligands, viz., o,o"-dimethylene(tri-p-cresyl) bicyclophosphite (BCP), was studied as a promoter of Rh(acac)(CO)2 in hydrogenation and hydroformylation. BCP enhances the activity and stability of the catalyst much more strongly than analogous organophosphorus ligands used previously (triphenylphosphine, triphenyl phosphite, and etriolphosphite). A reason for this behavior of BCP was studied using NMR spectroscopy, quantum-chemical calculations, and molecular simulation. The high sensitivity of the 1H NMR signals of the methylene groups of BCP toward complexation appears due to the high density of the highest occupied and lowest unoccupied MO of protons of the CH2 groups, especially those directed toward the P atom. The 1H and 31P NMR spectra indicate the formation of hydrides of two types (HRh(BCP)3 and HRh(BCP)4) directly upon the addition of BCP in amounts exceeding that corresponding to the BCP/Rh = 2 ratio to a solution of Rh((acac)(CO)2. The most probable source of the hydride ion is the BCP molecule itself, namely, the bridging CH2 groups. The molecular mechanics simulation showed that in the [Rh(BCP)3]+ complexes the aromatic rings of BCP formed two molecular cavities. These cavities can alternatively open and close, thus providing flexible screening of the catalytic site. This explains the unusual behavior of the Rh complexes with BCP in hydrogenation and hydroformylation. 相似文献
3.
Fadila Balegroune Pierre Braunstein Jérôme Durand Thierry Faure Daniel Grandjean Michael Knorr Maurizio Lanfranchi Chiara Massera Xavier Morise Antonio Tiripicchio 《Monatshefte für Chemie / Chemical Monthly》2001,132(8):885-896
Summary. Iodo derivatives of diphosphine-bridged heterobimetallic Fe—Pd and Fe—Pt complexeshave been prepared in which an alkoxysilyl
ligand bridges the two metals in a μ2−η2-SiO manner. In the course of their synthesis by halide exchange from (dppx = dppm (Ph2 PCH2 PPh2) or dppa (Ph2PNHPPh2); M = Pd or Pt), loss of the alkoxysilyl ligand occurred resulting in the formation of complexes in which a bridging iodide has
replaced, as a 3e−-donor, the bridging alkoxysilyl ligand. These complexes of formula (M = Pd, Pt are better prepared by reaction of with [MI2(cod)]. The crystal structures of (2a), (2b), and · CH2Cl2 (3b · CH2Cl2) have been determined by X-ray diffraction.
Received January 24, 2001. Accepted February 12, 2001 相似文献
4.
Summary. Rh(III) polypyridine complexes ([Cp
*Rh(ppy)(H2O)]2+; ppy = 2,2′-bipyridine, 2,2′-bipyridine-4,4′-dicarboxylate, o-phenanthroline, tetrahydro-4,4′-dialkyl-bis-oxazole) oxidize in organic or aqueous alkaline solution primary and secondary alcohols to aldehydes or ketones and are thereby
reduced to the Rh(I) complexes Cp
*Rh(ppy). The Rh(III) form can be regenerated byoxidants like pyruvate or oxygen, making the reaction quasi-catalytic. The reaction follows anautocatalytic pathway; hydrogen transfer from the α-CH2 group of an alcoholate complex [Cp
*Rh(ppy)(OR)]+ to Cp
*Rh(I)(ppy) is suggested to yield the Rh(II) intermediate Cp
*Rh(ppy)H as the key and rate determining step. The knowledge of Rh(III)/Rh(I) redox potentials allows to estimate the thermodynamic
driving force of the reaction which is not more than about 300 mV. 相似文献
5.
Chien-Hong Cheng Dan E. Hendriksen R. Eisenberg 《Journal of organometallic chemistry》1977,142(3):C65-C68
The rhodium(I) complex [Rh(CO)(PEt3)(mnt)]? (mnt = maleonitriledithiolate) reacts with a variety of alkyl halides to form acyl complexes isolated in the presence of excess PEt3 as five-coordinate species of formula [Rh(COR)(PEt3)2(mnt)]. The structure of the complex for R = n-Pr has been determined by an X-ray analysis, and is found to be a square-based pyramid with the acyl group in the apical position. Addition of HClO4 to the rhodium(I) anion in the presence of excess PEt3 yields rhodium(III) hydride, [RhH(CO)(PEt3)2(mnt)], while addition of acid to the rhodium(I) complex in CH3CN solution with ethylene present leads slowly to formation of an acyl complex which is isolated as [Rh(COEt)(PEt3)2(mnt)] upon phosphine addition. A novel alkyl group migration from the acyl carbon to a donor S atom is also observed in monophosphine systems. 相似文献
6.
o-Hydroxyacetophenone (N-benzoyl)glycyl hydrazone (o-HABzGH) forms complexes of the types [M(o-HABzGH)Cl2(H2O)2]Cl and [M(o-HABzGH-2H)OH(H2O)2], where M = Y(III), Gd(III), Tb(III) and Dy(III). The complexes have been characterized by elemental analyses, molar conductance,
magnetic susceptibility, infrared, electronic,1H NMR and13C NMR spectral techniques. The nephelauxetic ratio (β), covalency (δ), bonding parameter (b
1/2) and angular overlap parameter (η) have been calculated from Dy(III) complexes. Infrared and NMR spectral studies show thato-HABzGH acts as a neutral bidentate ligand in the adduct complexes and as a dinegative tridentate one in the neutral complexes.
A coordination number of six has been proposed for the metal ion in all the complexes. 相似文献
7.
Christoph Schädle Dr. Andreas Fischbach Dr. Eberhardt Herdtweck Prof. Dr. Karl W. Törnroos Prof. Dr. Reiner Anwander 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(48):16334-16341
Yttrocene‐carboxylate complex [Cp*2Y(OOCArMe)] (Cp*=C5Me5, ArMe=C6H2Me3‐2,4,6) was synthesized as a spectroscopically versatile model system for investigating the reactivity of alkylaluminum hydrides towards rare‐earth‐metal carboxylates. Equimolar reactions with bis‐neosilylaluminum hydride and dimethylaluminum hydride gave adduct complexes of the general formula [Cp*2Y(μ‐OOCArMe)(μ‐H)AlR2] (R=CH2SiMe3, Me). The use of an excess of the respective aluminum hydride led to the formation of product mixtures, from which the yttrium‐aluminum‐hydride complex [{Cp*2Y(μ‐H)AlMe2(μ‐H)AlMe2(μ‐CH3)}2] could be isolated, which features a 12‐membered‐ring structure. The adduct complexes [Cp*2Y(μ‐OOCArMe)(μ‐H)AlR2] display identical 1J(Y,H) coupling constants of 24.5 Hz for the bridging hydrido ligands and similar 89Y NMR shifts of δ=?88.1 ppm (R=CH2SiMe3) and δ=?86.3 ppm (R=Me) in the 89Y DEPT45 NMR experiments. 相似文献
8.
Organorhodium complexes, such as RhH(PPh3)4, RhH(CO)(PPh3)3, Rh(η3-C3H4Ph)(CO)(PPh3)2, and RhH(dppe)2 [dppe = 1,2-bis(diphenylphosphinoethane)], catalyze polymerization of phenylallene and of 4-methylphenylallene at 60 °C. High-molecular-weight polymers (Mn>4×105) are isolated from the reaction products by removing the low-molecular-weight (Mn<3×103) acetone-soluble fraction. The NMR (1H and 13C{1H}) spectra of poly(phenylallene) (1) and poly(4-methylphenylallene) (2) show the structure formed through selective 2,3-polymerization of the monomers, while similarly obtained poly(2-naphthylallene) (3) is characterized only by 1H NMR spectroscopy due to its low solubility in common organic solvents. 4-Fluorophenylallene and 4-(trifluoromethyl)-phenylallene do not polymerize under similar conditions in the presence of RhH(PPh3)4 catalyst but are turned into low-molecular-weight oligomers. CoH(N2)(PPh3)3-catalyzed polymerization of phenylallene and 4-methylphenylallene at room temperature gives the corresponding polymers with molecular weights in the range Mn=(9–15)×104, in high yields. © 1997 John Wiley & Sons, Ltd. 相似文献
9.
Arlen Ferrari Massimo Merlin Silvana Sostero Heinz Rüegger LuigiM. Venanzi 《Helvetica chimica acta》1999,82(9):1454-1457
The photochemical rearrangement of [Rh(η4-1,5-cod)TpMe2](TpMe2=hydrotris(3,5-dimethylpyrazolyl)borato, 1,5-cod=cycloocta-1,5-diene) to the new compound [Rh(η4-1,3-cod)TpMe2] ( 2 ) is described. The characterization of 2 was carried out using 1H-, 13C-, and 103Rh-HMQC-NMR spectroscopy. Photolysis of 2 is a versatile entry point into the organometallic chemistry of the {RhTpMe2} fragment as it can be used to produce a) hydrido-carbonyl ([Rh(CO)H2TpMe2]), b) hydrido-phenyl-phosphite ([RhH(Ph)(P(OMe)3)TpMe2]), and c) ethoxide-hydrido-phosphite ([RhH(OEt)(P(OMe)3)TpMe2]) complexes. 相似文献
10.
N. N. Ezhova G. A. Korneeva V. I. Kurkin E. V. Slivinsky 《Russian Chemical Bulletin》1995,44(6):1027-1030
Carbonylrhodium complexes formed during hydroformylation of CH2O from various rhodium precursors were investigated byin situ IR spectroscopy. It was found that under the conditions of the hydroformylation of CH2O inN,N-dimethylacetamide (DMAA), RhH(CO)(PPh3)3, RhCl(CO)(PPh3)2, RhCl(PPh3)3, RhCl(CO)(PBu3)2, and [RhCl(CO)2]2 form complex systems that necessarily contain anionic complexes, [Rh(CO)2Lx(DMAA)y]– (L = PPh3, PBu3,x = 1 to 2,y = 1 to 0; [Rh(CO)4]–). The participation of ionic structures in the hydroformylation of CH2O, most likely, in the step of the activation of CH2O, was proven by kinetic techniques.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1066–1069, June, 1995. 相似文献
11.
Wen-J. Mei Yu-Z. Ma Jie Liu Jin-C. Chen Kang-C. Zheng Liang-N. Ji Jun-H. Yao 《Transition Metal Chemistry》2006,31(3):277-285
A series of ruthenium(II) complexes with electron-donor or electron-acceptor groups in intercalative ligands, [Ru(phen)2(o-MOP)]2+ (1), [Ru(phen)2(o-MP)]2+ (2), [Ru(phen)2(o-CP)]2+ (3) and [Ru(phen)2(o-NP)]2+ (4), have been synthesized and characterized by elementary analysis, ES-MS, 1H NMR, electronic absorption and emission spectra. The binding properties of these complexes to CT-DNA have been investigated
by spectroscopy and viscosity experiments. The results showed that these complexes bind to DNA in intercalation mode and their
intrinsic binding constants (Kb) are 1.1, 0.35, 0.53 and 1.7 × 105 M−1, respectively. The subtle but detectable differences occurred in the DNA-binding properties of these complexes are mainly
ascribed to the electron-withdrawing abilities of substituents (–OCH3 < –CH3 < –Cl < –NO2) on the intercalative ligands as well as the intramolecular H-bond (for substituent –OCH3) which increase the planarity area of the intercalative ligand to some extent. The density functional theory (DFT) calculations
were also performed and used to further discuss the trend in the DNA-binding affinities of these complexes. 相似文献
12.
Pd(II) complexes of Schiff bases and their application as catalysts in Mizoroki–Heck and Suzuki–Miyaura cross‐coupling reactions 下载免费PDF全文
Schiff bases of 2‐(phenylthio)aniline, (C6H5)SC6H4N?CR (R = (o‐CH3)(C6H5), (o‐OCH3)(C6H5) or (o‐CF3)(C6H5)), and their palladium complexes (PdLCl2) were synthesized. The compounds were characterized using 1H NMR and 13C NMR spectroscopy and micro analysis. Also, electrochemical properties of the ligands and Pd(II) complexes were investigated in dimethylformamide–LiClO4 solution with cyclic and square wave voltammetry techniques. The Pd(II) complexes showed both reversible and quasi‐reversible processes in the ?1.5 to 0.3 V potential range. The synthesized Pd(II) complexes were evaluated as catalysts in Mizoroki–Heck and Suzuki–Miyaura cross‐coupling reactions. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
13.
Schinzel S Müller R Riedel S Werner H Kaupp M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(26):7228-7235
The unusual bridging and semi‐bridging binding mode of tertiary phosphanes, arsanes, and stibanes in dinuclear low‐valent Group 9 complexes have been studied by density functional methods and bonding analyses. The influence of various parameters (bridging and terminal ligands, metal atoms) on the structural preferences and bonding of dinuclear complexes of the general composition [A1 M1(μ‐CH2)2(μ‐EX3)M2 A2] (M1, M2=Co, Rh, Ir; A1, A2=F, Cl, Br, I, κ2‐acac; E=P, As, Sb, X=H, F, CH3) has been analyzed. A number of factors have been identified that favor bridging or semi‐bridging modes for the phosphane ligands and their homologues. A more symmetrical position of the bridging ligand EX3 is promoted by more polar E? X bonding, but by less electronegative (softer) terminal anionic ligands. Among the Group 9 metal elements Co, Rh, and Ir, the computations clearly show that the 4d element rhodium exhibits the largest preference for a {M1(μ‐EX3)M2} bridge, in agreement with experimental observation. Iridium complexes should be valid targets, whereas cobalt does not seem to support well a symmetric bridging mode. Analyses of the Electron Localization Function (ELF) indicate a competition between a delocalized three‐center bridge bond and direct metal–metal bonding. 相似文献
14.
15.
T. A. Stromnova S. T. Orlova D. N. Kazyul'kin I. P. Stolyarov I. L. Eremenko 《Russian Chemical Bulletin》1990,49(1):150-153
The reaction of the tetranuclear cluster Pd4(CO)4(OOCCF3)4 witho-nitrosotoluene afforded the Pd11-containing complex [o-(NO)(CH2)C6H4]2Pd2(μ-OOCCF3)2. The elimination of CO2 and the formation of organic products of transformation of tolylnitrene species (azotoluene, ditolylamine, and tolylisocyanate)
were observed in the course of the reaction. The title complex was characterized by IR and1H NMR spectroscopy. Its structure was established by X-ray diffraction analysis. It was suggested that the reaction proceeds
through intermediate formation of nitrene complexes.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 147–150, January, 2000. 相似文献
16.
T. A. Stromnova S. T. Orlova D. N. Kazyul'kin I. P. Stolyarov I. L. Eremenko 《Russian Chemical Bulletin》2000,49(1):150-153
The reaction of the tetranuclear cluster Pd4(CO)4(OOCCF3)4 witho-nitrosotoluene afforded the Pd11-containing complex [o-(NO)(CH2)C6H4]2Pd2(μ-OOCCF3)2. The elimination of CO2 and the formation of organic products of transformation of tolylnitrene species (azotoluene, ditolylamine, and tolylisocyanate)
were observed in the course of the reaction. The title complex was characterized by IR and1H NMR spectroscopy. Its structure was established by X-ray diffraction analysis. It was suggested that the reaction proceeds
through intermediate formation of nitrene complexes.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 147–150, January, 2000. 相似文献
17.
D. Saravanabharathi T. S. Venkatakrishnan M. Nethaji S. S. Krishnamurthy 《Journal of Chemical Sciences》2003,115(5-6):741-749
Rhodium(I) complexes of the hybrid ylide-phosphine ligands, Ph2P(CH2)
n
PPh2(CHC(O)C6H5) (n = 1: dppm-yl, or 2: dppe-yl) have been synthesised from [Rh(μ-C1)(COD)]2 (COD = 1,5-cyclooctadiene) and characterized by NMR spectroscopic and X-ray structural methods. The dppe-yl behaves as an
ambidentate ligand; it functions as a monodentate P-donor ligand with a dangling ylidic carbon in the neutral chloro complex,
[(COD)Rh(Cl)(dppe-yl)] (1), whereas replacement of the chloride by a non-coordinating counter anion results in the formation of the complexes, [(COD)Rh(L-L’)]+ (L-L’ = dppe-yl (2) or dppm-yl (3)) respectively in which the ligands are bonded to the metal via the phosphorus and the ylidic carbon atoms. The 1,5-cyclooctadiene
(COD), present in the Rh(I) precursor, remains intact in the products. The structures of1,2 and3 have been confirmed by X-ray crystallography.
Dedicated to Professor C N R Rao on his 70th birthday 相似文献
18.
CH Bond Activation with Triel Metals: Indium and Gallium Zwitterions through Internal Hydride Abstraction in Rigid Salan Ligands 下载免费PDF全文
Nicolas Maudoux Dr. Jian Fang Dr. Thierry Roisnel Dr. Vincent Dorcet Prof. Dr. Laurent Maron Prof. Dr. Jean‐François Carpentier Dr. Yann Sarazin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7706-7717
The hydropyrimidine salan (salan=N,N′‐dimethyl‐N,N′‐bis[(2‐hydroxyphenyl)methylene]‐1,2‐diaminoethane) proteo‐ligands with a rigid backbone {ON^(CH2)^NO}H2 react with M(CH2SiMe3)3 (M=Ga, In) to yield the zwitterions {ON^(CH+)^NO}M?(CH2SiMe3)2 (M=Ga, 2 ; In, 3 ) by abstraction of a hydride from the ligand backbone followed by elimination of dihydrogen. By contrast, with Al2Me6, the neutral‐at‐metal bimetallic complex [{ON^(CH2)^NO}AlMe]2 ( [1]2 ) is obtained quantitatively. The formation of indium zwitterions is also observed with sterically more encumbered ligands containing o‐Me substituents on the phenolic rings, or an N (CHPh) N moiety in the heterocyclic core. Overall, the ease of C?H bond activation follows the order Al?Ga<In. Experimental data based on model complexes, XRD studies, and 2H NMR spectroscopy show that the formation of the Ga/In zwitterion involves rapid release of SiMe4 followed by evolution of H2, and suggest the formation of a transient metal‐hydride species. DFT calculations indicate that the systems {ON^(CH2)^NO}H2+M(CH2SiMe3)3 (M=Al, Ga, In) all initially lead to the formation of the neutral monophenolate dihydrocarbyl species through a single protonolysis. From here, the thermodynamic product, the model neutral‐at‐metal complex 1 , is formed in the case of aluminum after a second protonolysis. On the other hand, lower activation energy pathways lead to the generation of zwitterionic complexes 2 and 3 in the cases of gallium and indium, and the formation of these zwitterions obeys a strict kinetic control; the computations suggest that, as inferred from the experimental data, the reaction proceeds through an instable metal‐hydride species, which could not be isolated synthetically. 相似文献
19.
Ezhova M. B. Patrick B. O. James B. R. Ford M. E. Waller F. J. 《Russian Chemical Bulletin》2003,52(12):2707-2714
Interaction of the cis-[Rh(PR3)2(Solv)2]PF6 complexes (R = Ar or R3 = Ph2Me, Solv — solvent) under Ar with semicarbazones bearing a phenyl group on the imine-C atom gives the rhodium(iii)-hydrido-bis(phosphine)-orthometallated semicarbazone species [RhH(PR3)2{(o-C6H4(R")C=N—N(H)CONH2}]PF6 (R" = Me or Et), which are characterized generally by elemental analysis, 31P{1H} and 1H NMR spectroscopy, and mass-spectrometry. The PPh3-containing complex with R" = Me, structurally characterized by X-ray analysis, reveals coordination of the semicarbazone by the ortho-C atom, the imine-N atom, and the amide-carbonyl group. For a semicarbazone containing no Ph group, the rhodium(i) complex [Rh(PR3)2(Et(Me)C=N—N(H)CONH2)]PF6, containing the 2-semicarbazone bonded via the imine-N and carbonyl, is formed. Attempts to hydrogenate the C=N moiety in the complexes or to catalytically hydrogenate the semicarbazones were unsuccessful. 相似文献
20.
Bio‐Inspired Transition Metal–Organic Hydride Conjugates for Catalysis of Transfer Hydrogenation: Experiment and Theory 下载免费PDF全文
Alex McSkimming Dr. Bun Chan Dr. Mohan M. Bhadbhade Dr. Graham E. Ball Prof. Stephen B. Colbran 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):2821-2834
Taking inspiration from yeast alcohol dehydrogenase (yADH), a benzimidazolium (BI+) organic hydride‐acceptor domain has been coupled with a 1,10‐phenanthroline (phen) metal‐binding domain to afford a novel multifunctional ligand ( L BI+) with hydride‐carrier capacity ( L BI++H?? L BIH). Complexes of the type [Cp*M( L BI)Cl][PF6]2 (M=Rh, Ir) have been made and fully characterised by cyclic voltammetry, UV/Vis spectroelectrochemistry, and, for the IrIII congener, X‐ray crystallography. [Cp*Rh( L BI)Cl][PF6]2 catalyses the transfer hydrogenation of imines by formate ion in very goods yield under conditions where the corresponding [Cp*Ir( L BI)Cl][PF6] and [Cp*M(phen)Cl][PF6] (M=Rh, Ir) complexes are almost inert as catalysts. Possible alternatives for the catalysis pathway are canvassed, and the free energies of intermediates and transition states determined by DFT calculations. The DFT study supports a mechanism involving formate‐driven Rh?H formation (90 kJ mol?1 free‐energy barrier), transfer of hydride between the Rh and BI+ centres to generate a tethered benzimidazoline (BIH) hydride donor, binding of imine substrate at Rh, back‐transfer of hydride from the BIH organic hydride donor to the Rh‐activated imine substrate (89 kJ mol?1 barrier), and exergonic protonation of the metal‐bound amide by formic acid with release of amine product to close the catalytic cycle. Parallels with the mechanism of biological hydride transfer in yADH are discussed. 相似文献