Transition Metal Phosphine Research Articles

Catalytic Decomposition of Methyl Formate in the Presence of Transition Metal Complexes, Phosphine Ligands and Water

Catalytic Decomposition of Methyl Formate in the Presence of Transition Metal Complexes, Phosphine Ligands and Water

ChemInform Abstract: Catalytic, Enantioselective Alkylation of α‐Imino Esters Using Late Transition Metal Phosphine Complexes as Catalysts.

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Catalytic, Enantioselective Alkylation of α-Imino Esters Using Late Transition Metal Phosphine Complexes as Catalysts

Over the past several years, highly effective methods for enantioselective aldol additions catalyzed by Lewis acids have been developed.1 Analogous alkylations of imines, however, have not been nearly as well studied nor as successful.2 R-Imino esters are almost unstudied in Lewis acid-catalyzed reactions,3 but are especially attractive imine substrates for the efficient syntheses of natural product precursors,4 pharmaceutically active compounds,5 and nonnatural amino acids;6 the last category has recently received much attention as peptidomimetics7 and in sitedirected mutagenesis studies.8 In a recent report, we demonstrated that select late transition metals can catalyze the cis-trans isomerization of prolyl peptides through simultaneous coordination of the metal to the amide nitrogen (Na) and the side chain carbonyl group (Figure 1, a).9 Catalysis fails to occur on simple amides that do not contain an additional binding site. These results prompted us to investigate whether analogous coordination of a transition metal to the nitrogen of a functionalized imine and a chelating carbonyl group could activate the substrate toward a highly enantioselective addition of nucleophiles (Figure 1, b). From our point of view, activated R-imino esters 1 seemed ideal substrates for Lewis acid catalyzed asymmetric alkylations for several reasons: (1) alkylation occurs readily at the imine carbon with a variety of nucleophiles, (2) the electron-withdrawing R-ester group provides additional activation of the imino group to nucleophilic attack, (3) the imine N and carbonyl O can form a stable five-membered chelate ring with a chiral Lewis acid catalyst (eq 1),10 providing additional rigidity to an activated complex and potentially enhanced product selectivity, and (4) alkylation of imine derivatives 1 with enol silane nucleophiles can lead to substituted γ-oxo R-amino acids (aspartic acid analogues) that comprise a class of interesting and useful biologically active natural compounds.11 We report herein a means to alkylate R-imino esters enantioselectively in up to 98% ee and in high chemical yields with enol silanes using chiral catalytic late transition metal phosphine complexes selected from Ag(I), Cu(I), Ni(II), and Pd(II) (eq 2).

Development of Transition Metal Phosphine Complexes as Electrocatalysts for CO2 and CO Reduction

[Pd(triphosphine)(solvent)](BF4)2 complexes have been developed as catalysts for the electrochemical reduction of CO2 to CO. A variety of structural features of these complexes have been varied to determine their effects on the mechanism, rates, and decomposition products of these catalysts. The structural features varied included substituents on the triphosphine ligand, the size of the chelate bite, and donor atoms of the tridentate ligand. Bimetallic catalysts containing two [Pd(triphosphine)(solvent)] units have been prepared and characterized that exhibit a cooperative interaction during CO2 reduction with large rate enhancements compared to their monomeric analogs. As a first step in developing electrocatalysts capable of reducing CO, electrochemically generated hydrides of Ni and Pd have been shown to transfer their hydride ligands to coordinated CO to form formyl complexes.

Determination of 113Cd shielding tensor components in cadmium-phosphine complexes from 31-decoupled 113Cd cross-polarisation/magic angle spinning spectra

Owing to the simultaneous presence of various anisotropic interactions within the isolated M- 31P and M( 31P) 2 fragments in solid transition metal phosphine complexes MX 2 · PR 3 and MX 2 · 2PR 3 with, for instance, M = Cd, Hg or Pt, it is not normally possible to unequivocally determine the shielding tensor components of the metal nucleus M from simple 113Cd, 199Hg or 195Pt cross-polarisation/magic angle spinning (CP/MAS) spectra. In this paper it is shown that additional 31P on-resonance high-power decoupling during the acquisition time does allow the determination of the shielding tensor components of M from CP/MAS spectra. Two cadmium(II) complexes, Cd(OAc) 2 · Pchex 3, (chex = cyclohexyl) and Cd(ClO 4) 2 · 2Pchex 3 were chosen as examples; the 113Cd CP/MAS experiments were carried out at a low external magnetic field strength B 0 = 2.35 T.

The role of dioxygen in hydrosilylation of alkenes catalyzed by ruthenium phosphine complexes

Catalytic hydrosilylation of CC bonds in alkenes in the presence of Ru(II)-phosphine complexes takes place only for alkoxy-substituted silanes in the absence of solvent and in the presence of small amounts of O 2. The activation effect of “trace” O 2, noted previously for rhodium and other transition metal phosphine complex catalysts for several catalytic processes, has been little studied to date. In this work, oxygen is considered to cause removal of phosphine as its oxide, formation of intermediate dioxygen complexes (followed by oxygenation of RuSi to an RuOSi moiety with elimination of disiloxane) and possible formation of Ru(IV) species. The studies include the characterization of isolated intermediates (well defined complexes or their mixtures) from an RuCl 2(PPh 3) 3− HSi(OC 2H 5) 3 system and general mechanisms for the hydrosilylation of alkenes in the presence of Ru(II) precursors are discussed.

CP/MAS NMR of Heavy Spin-1/2 Nuclei at B0 = 2.35T

Perspectives of CP/MAS NMR at low external magnetic field (B0=2.35T) are discussed. Applications are illustrated for the case of heavy spin-1/2 nuclei such as 195Pt and 199Hg: 195Pt and 199Hg CP/MAS spectra of a variety of organometallic compounds are reported. Aspects of shielding anisotropics, of 195Pt-35/37Cl interactions and of 31P-M (M=Cd, Hg, Pt) coupling in transition metal phosphine complexes will be briefly addressed

Transition Metal Phosphine Complexes Possessing Phase Transfer Function. Preparation and Reactivities of Palladium Complexes Containing Quaternary Ammonium Groups

Abstract A new type of phosphine ligands (L) bearing quaternary ammonium as a functional group was synthesized. Their palladium complexes, PdBr2L2, readily underwent halogen exchange with powdered NaI under two-phase conditions, and efficiently catalyzed the fluorocarbonylation of phenyl bromide with powdered KF at atmospheric pressure of CO.

The reaction of coarse-grain metal powders with phosphoranes: a facile activation of metallic reagents and a novel route to metal–phosphine complexes. The X-ray crystal structures of Mnl2(PPhMe2) and FeBr3(PPhMe2)2

A route to new and existing transition metal phosphine complexes is provided by the reaction of coarse-grain metal powders and phosphoranes in diethyl ether, as exemplified here by Nil3(PMe3)2, FeBr3(PPhMe2)2 and Mnl2(PPhMe2).

Structural systematics: the role of P-A .sigma.* orbitals in metal-phosphorus .pi.-bonding in redox-related pairs of M-PA3 complexes (A = R, Ar, OR; R = alkyl)

The geometry variations in the M-PA 3 units of 24 transition metal-phosphine and -phosphite complexes whose crystal structures are known for multiple oxidation states of the complex are tabulated and discussed. Conclusions are drawn with regard to the effect of oxidation at the metal on M-P π-back-bonding and the consequent structural effects on the PA 3 ligand

Homogeneous hydrogenation of nitroaliphatic compounds catalyzed by group VIII transition metal phosphine complexes

A variety of Group VIII transition metal phosphine complexes were shown to be active catalysts for hydrogenation of nitroaliphatic compounds. The catalysis was determined to be homogeneous based on results of selective catalyst poisoning experiments using dibenzo[a,e]cyclooctatetraene and Hg. A deuterium labeling study showed that in the absence of added base the primary hydrogenation pathway does not involve intermediates containing C=N bonds.

Transition Metal Phosphine Complexes Possessing a Phase Transfer Function. Preparation and Catalytic Reactivity of Palladium Phosphine Complexes Containing Crown Ethers

Abstract Crown-functionalized triarylphosphines and their palladium complexes were synthesized and characterized. The palladium complexes were found to fulfil the concerted function of the transition metal catalyst and the phase transfer catalyst in the two-phase reduction of 1-chloromethylnaphthalene with formate salts.

Structural evidence for the participation of P–X σ* orbitals in metal–PX3bonding

Examination of metal–phosphorus and phosphorus–substituent atom bond length in a series of reduction–oxidation related pairs of transition metal phosphine complexes yields evidence of the participation of P–substitution σ* orbitals in the π-acceptor function of the phosphine.

ChemInform Abstract: DIOP AS A LIGAND IN ASYMMETRIC CATALYSIS USING TRANSITION METAL PHOSPHINE COMPLEXES

Chemischer InformationsdienstVolume 15, Issue 20 Reviews ChemInform Abstract: DIOP AS A LIGAND IN ASYMMETRIC CATALYSIS USING TRANSITION METAL PHOSPHINE COMPLEXES J. + WEISHAEUPTL, J. + WEISHAEUPTLSearch for more papers by this author J. + WEISHAEUPTL, J. + WEISHAEUPTLSearch for more papers by this author First published: May 15, 1984 https://doi.org/10.1002/chin.198420366Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume15, Issue20May 15, 1984 RelatedInformation

Metal Salts and Complexes as Structural Models and Templates for The Solid State Polymerization of Substituted Acetylenes

Abstract In an extensive study of the preparation and solid-state reactivity of transition metal phosphine complexes it was found that nearest-neighbor interactions, nucleation, temperature, doping, polymorphism and crystal symmetry greatly influenced the course of the thermal solid state reactions. With the perspective of the solid state chemistry developed by Morawetz and Schmidt, the principles and techniques developed in our laboratory have been applied to the radiation-induced solid state polymerization of metal alkynoate complexes, leading to the first rationally designed synthesis of substituted polyacetylenes in the solid state. The structural principles which led to this synthesis are described herein. The reactivity of several different monomer phases is contrasted in the context of crystal structure, metal electronic structure and radiation sensitivity.

Synthesis of 2-Substituted Oxazoles by Cross-Coupling of Grignard Reagents with 2-(Methylthio)-oxazoles Employing Transition Metal-Phosphine Catalysis

Synthesis of 2-Substituted Oxazoles by Cross-Coupling of Grignard Reagents with 2-(Methylthio)-oxazoles Employing Transition Metal-Phosphine Catalysis

ChemInform Abstract: TRANSITION METAL PHOSPHINE COMPLEXES POSSESSING A PHASE TRANSFER FUNCTION. PREPARATION AND PROPERTIES OF POLYETHER‐SUBSTITUTED PHOSPHINES AND THEIR PALLADIUM COMPLEXES

AbstractAus den Alkoxyalkylhalogeniden (II) werden über die entsprechenden Grignard‐Verbindungen die Phosphine (IV) und (V) hergestellt, die in die Palladium‐ Komplexe (VII) übergeführt werden.

TRANSITION METAL PHOSPHINE COMPLEXES POSSESSING A PHASE TRANSFER FUNCTION. PREPARATION AND PROPERTIES OF POLYETHER-SUBSTITUTED PHOSPHINES AND THEIR PALLADIUM COMPLEXES

Abstract For the purpose of endowing transition metal phosphine complexes with a phase transfer function, tertiary phosphines modified by polyether chains were prepared, and their properties were examined. The palladium complexes of these phosphines were very efficient as catalysts for the reduction of bromobenzene with sodium hydride under a liquid–solid two-phase condition.

P. S. Pregosin and R. W. Kunz. NMR basic principles and progress, Volume 16: 31P and 13C NMR of transition metal phosphine complexes. Springer‐Verlag, Berlin, 1979. PP. 156. $39.60, DM72.00

Organic Magnetic ResonanceVolume 13, Issue 6 p. 467-467 Book Review P. S. Pregosin and R. W. Kunz. NMR basic principles and progress, Volume 16: 31P and 13C NMR of transition metal phosphine complexes. Springer-Verlag, Berlin, 1979. PP. 156. $39.60, DM72.00 G. Mavel Ircha, G. Mavel IrchaSearch for more papers by this author G. Mavel Ircha, G. Mavel IrchaSearch for more papers by this author First published: June 1980 https://doi.org/10.1002/mrc.1270130617AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume13, Issue6June 1980Pages 467-467 RelatedInformation

Chemistry of transition metal-phosphine and -phosphite complexes. 1. Photochemical substitution reactions of tetrakis(triphenyl phosphite)cobalt(I) hydride

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemistry of transition metal-phosphine and -phosphite complexes. 1. Photochemical substitution reactions of tetrakis(triphenyl phosphite)cobalt(I) hydrideHarold L. Conder, Arlene R. Courtney, and David DeMarcoCite this: J. Am. Chem. Soc. 1979, 101, 6, 1606Publication Date (Print):March 1, 1979Publication History Published online1 May 2002Published inissue 1 March 1979https://doi.org/10.1021/ja00500a046RIGHTS & PERMISSIONSArticle Views281Altmetric-Citations8LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (169 KB) Get e-Alerts Get e-Alerts