Search results for "PENTAD"
showing 10 items of 589 documents
Synthèse et caractérisation de phosphine, borane, amine sur plateforme ferrocène polyfonctionnelle
2016
Ferrocene platforms are useful in coordination chemistry and catalysis thanks to their robustness and versatile functionalization. Ferrocene backbone allows the implantation of several key functional groups in a restricted space, inducing close proximity and potential polyfunctional cooperation (see for instance ferrocenyl polyphosphine chemistry). Ansa ferrocene and ferrocene bearing conformational control inducing groups maximizing the proximity of key groups have been widely reported.The first part of this thesis focuses on the synthesis of new borylated cyclopentadienyl, and their use in formation of borylated metallocenes bearing conformational constraints. NMR analysis and DFT calcula…
On the enhancement of stereoselection by cooperation between chiral auxiliaries. Asymmetric diels-alder reactions with fumaric acid bis ((S)-proline …
1989
Abstract Fumaric acid bis ((S)-proline benzyl ester) amide reacts with cyclopentadiene in thermal and Lewis acid catalyzed Diels-Alder reactions to give the cycloadducts with high yields and diastereomeric ratios up to 100:1.
A Trinuclear Aqua Cyano‐Bridged Ruthenium Complex [{(η 5 ‐C 5 H 5 )(PPh 3 ) 2 Ru(μ‐CN)} 2 RuCl 2 (PPh 3 )(H 2 O)]PF 6 : Synthesis, Characterization a…
2007
The organometallic trinuclear aqua cyano-bridged complex [{(η5-C5H5)(PPh3)2Ru(μ-CN)}2RuCl2(PPh3)(H2O)]PF6 (1), in which the fragment [RuCl2(PPh3)(H2O)] acts as a bridge and an acceptor group between the two terminal cyclopentadienyl ruthenium cyano moieties, was isolated in moderate yield from the reaction of [(η5-C5H5)(PPh3)2RuCN] with [RuCl2(PPh3)3] in THF. To the best of our knowledge, compound 1 is one of the few examples of a trinuclear array of ruthenium fragments bridged by the nitrogen atom of the–C≡N– group (Ru–C≡N–Ru′–N≡C–Ru) with a Ru-coordinated water molecule. The new aqua complex was structurally characterized by FTIR, 1H, 13C, and 31P NMR spectroscopy, mass spectrometry, elem…
Hexaphosphine: A Multifaceted Ligand for Transition Metal Coordination
2011
We report the synthesis and characterization of the first ferrocenyl polyphosphane incorporating six phosphorus donor atoms. In this unique ligand, the cyclopentadienyl rings of the ferrocenyl backbone adopt a staggered position, which leads to a piano-stool arrangement for each of the two sets of three P atoms facing the same direction. As a consequence of its remarkable flexibility, this hexaphosphane displays versatile coordination behaviour towards metals, leading to unexpected structures of palladium and platinum bimetallic complexes. Analogous molybdenum and rhodium complexes are more classical.
Der austausch des cyclopentadienylliganden im methylcyclopentadienylmangan(I)tricarbonyl. Untersuchungen zur konkurrierenden komplexbildung mit methy…
1981
Abstract Exchange of the cyclopentadienyl ligand in methylcyclopentadienylmanganese(I) tricarbonyl with methyl-substituted benzenes is catalysed by AlCl 3 + HCl and leads to the cations [arene-Mn(CO) 3 ] + . The methylbenzenes isomerize and disproportionate during the reaction. The distribution of the arenes between the solution and the complex ions has been determined. The different complexing abilities of the arenes lead to the proposal of an associative mechanism for the ligand exchange.
Cyclopenta[l]phenanthrenyl and Cyclopenta[a]acenaphthylenyl Half-Sandwich Complexes of Ruthenium as Racemization Catalysts for Secondary Alcohols
2008
Several half-sandwich complexes of ruthenium with cyclopenta[l]phenanthrenyl and cyclopenta[a]acenaphthylenyl ligands containing fused aromatic ring substituents on the cyclopentadienyl ring were p...
Synthesis and Characterization of Yttrium Complexes Containing a Tridentate Linked Amido−Cyclopentadienyl Ligand
1998
The reaction of dilithium salts of the tridentate linked amido−cyclopentadienyl ligands Li2(C5Me4SiMe2NCH2CH2X) (X = OMe, NMe2, CH2OMe) with [Y(o-C6H4CH2NMe2)Cl2(LiCl)(THF)4] and Y(η5-C5H5)Cl2(THF)3 give chloro-bridged ate complexes of the type [Li(THF)][Y(η5:η1-C5Me4SiMe2NCH2CH2X)(R)Cl], where R = o-C6H4CH2NMe2, η5-C5H5.
Synthesis, Spectroscopic Characterization, and Crystal Structure Determination of Cationic [(Cyclopentadienyl)dicarbonyliron](alkynyl)‐aminocarbene C…
1996
(Alkynoyl)iron complexes 1, Cp(CO)2Fe(OCCCR) (R = CH3, Ph, SiMe3), were synthesized by applying a mixed anhydride procedure and transformed into the cationic methoxycarbene complexes 2, [Cp(CO)2 Fe(C(OMe)CCR)+]-[PF6–]. Primary amines H2NR′ react with the methoxycarbene complexes to furnish exclusively cationic aminocarbene complexes 3, [Cp(CO)2 Fe(C(NHR′)CCR)+][PF6–], or (2-methoxyvinyl)aminocarbene complexes 5. The spectroscopic properties of the new complexes are discussed. The (alkynyl)-aminocarbene complexes 3e and 3f were characterized by X-ray crystal structure analysis.
Cationic Iron Aminocarbene Complexes as Dienophiles in Diels‐Alder Reaction with Cyclopentadiene
1996
The cationic iron (alkynyl)aminocarbene complexes [Cp(CO)2Fe(C(NHR)CCSiMe3][PF6], (R C6H5, p-CH3C6H4) 1 derived from aromatic amines smoothly react with cyclopentadiene in dichloromethane to yield the cycloadducts 2. No reaction was observed for complexes derived from sterically demanding aliphatic amines, like L-alanine tert-butyl ester. For comparison, the alkynyl-substituted acyl iron compounds Cp(CO)2Fe(CO)CC (R SiMe3, C6H5) 3 were investigated, requiring TiCl4 catalysis to undergo the cycloaddition reaction. The structures of the cycloadducts 4 were determined by X-ray crystallography.
Dimeric Hydrido Complexes of Rare-Earth Metals Containing a Linked Amido−Cyclopentadienyl Ligand: Synthesis, Characterization, and Monomer−Dimer Equ…
2000
Dimeric hydrido complexes of lutetium, ytterbium, and yttrium containing a linked amido−cyclopentadienyl ligand, [Ln(η5:η1-C5Me4SiMe2NCMe2R)(L)(μ-H)]2 (Ln = Lu, Yb, Y; R = Me, Et; L = THF, PMe3), w...