Search results for "Phosphine"
showing 10 items of 618 documents
Synthesis of the first imidazolyl-triphosphines containing a Triphos unit
2007
Abstract Since biphasic liquid–liquid continuous-flow catalytic processes often require the use of cationic phosphine ligands for the metal sequestration in the polar phase, we have prepared the first imidazolyl triphosphines, named Triphosim and Triphosmim. These ligands contain the Triphos unit [-P(CH2CH2PPh2)] which is linked to the imidazole fragment and have been obtained in three steps from imidazole (or 2-methylimidazole), diethylvinylphosphonate and diphenylvinylphosphine with global yields of 42–48%. The Triphosim ligand adopts a tridentate P-coordination mode in a palladium dichloride complex and the reaction of the dangling imidazole function with alkyl halides leads to a new kin…
Synthesis, characterization and kinetics of the metallation of the intermediate compound to produce compound · (H2O) from Rh(II) tetraacetate
1998
Abstract Photochemical irradiation of mixtures of [Rh2(μ-O2CCH3)4]·(HOCH3)2 and P(2-(CH3O)C6H4)Ph2 (POMe) in CH2Cl2 solution (1:1 molar ratio) yields quantitatively compound [ Rh 2 (μ- O 2 CCH 3 ) 3 ( O 2 CCH 3 )(η 2 - P (2-( CH 3 O ) C 6 H 4 ) Ph 2 ]·( H 2 O ) (1) containing a POMe acting as a chelating equatorial ( P ) axial ( O ) donor ligand. This compound undergoes intramolecular CH activation reaction at one of the phenyl rings in CHCl3 or CH3COOH/toluene solution at room temperature to form the monometallated compound [ Rh 2 (μ- O 2 CCH 3 ) 3 (μ-( C C 3 H 4 ) P (2-( CH 3 O C 6 H 4 ) Ph )]· ( H 2 O ) ( 2 ). The kinetics of the 1 → bd2 reaction have been studied in acid media (CH3CO…
Uncommon coordination behaviour of P(S) and P(Se) units when bonded to carboranyl clusters: experimental and computational studies on the oxidation o…
2010
Oxidation of closo-carboranyl diphosphines 1,2-(PR(2))(2)-1,2-closo-C(2)B(10)H(10) (R=Ph, iPr) and closo-carboranyl monophosphines 1-PR(2)-2-R'-1,2-closo-C(2)B(10)H(10) (R=Ph, iPr, Cy; R'=Me, Ph) with hydrogen peroxide, sulfur and elemental black selenium evidences the unique capacity of the closo-carborane cluster to produce uncommon or unprecedented P/P(E) (E=S, Se) and P=O/P=S chelating ligands. When H(2)O(2) reacts with 1,2-(PR(2))(2)-1,2-closo-C(2)B(10)H(10) (R=Ph, iPr), they are oxidized to 1,2-(OPR(2))(2)-1,2-closo-C(2)B(10)H(10) (R=Ph, iPr). However, when S and Se are used, different reactivity is found for 1,2-(PPh(2))(2)-1,2-closo-C(2)B(10)H(10) and 1,2-(PiPr(2))(2)-1,2-closo-C(2)…
Kinetico-mechanistic studies of the acidolysis of Rh-C bonds in monocyclometallated dirhodium(II) acetato complexes; influence of electronic and ster…
2011
The protonation/demetallation reaction, in CD(3)COOD, of phosphine monometallated triacetato-bridged dirhodium(ii) complexes of general formulae [Rh(2)(μ-OOCCH(3))(3){(RC(5)CH(3))P(RC(6)H(4))(2)}(2)] has been studied from a kinetico-mechanistic perspective. The process has been monitored via the disappearance of the nuclear magnetic resonance signals of the protons present in the non-metallated ortho positions of the phosphine ligand and taking advantage of the relatively fast back metallation process that follows the acidolysis reaction, the sequence behaving as an overall equilibrium reaction. The process has a high associative character with important entropy demands, increasing both for…
Ag44(EBT)26(TPP)4Nanoclusters With Tailored Molecular and Electronic Structure
2021
Although atomically precise metalloid nanoclusters (NCs) of identical size with distinctly different molecular structures are highly desirable to understand the structural effects on the optical and photophysical properties, their synthesis remains highly challenging. Herein, we employed phosphine and thiol capping ligands featuring appropriate steric effects and synthesized a charge-neutral Ag NC with the formula Ag44 (EBT)26 (TPP)4 (EBT: 2-ethylbenzenethiolate; TPP: triphenylphosphine). The single-crystal X-ray structure reveals that this NC has a hollow metal core of Ag12 @Ag20 and a metal-ligand shell of Ag12 (EBT)26 (TPP)4 . The presence of mixed ligands and long V-shaped metal-ligand …
Zur Stereochemie der Oxidation chiraler, tertiärer Phosphine mit Dimethylsulfoxid
1976
Es wird uber den sterischen Verlauf der Oxidation der optisch aktiven, tertiaren Phosphine 3 and 4 mit Dimethylsulfoxid berichtet. Diese Umsetzung verlauft nur in Gegenwart elektrophiler Katalysatoren (Tabelle 1). Je nach Art and Menge des Katalysators zeigt die Stereochemie der Reaktion entweder uberwiegende Inversion oder Retention der Konfiguration am Phosphor an (Tabellen 2, 3); in einigen Fallen wird jedoch fast vollstandige Racemisierung beobachtet (Tabelle3). Auf der Grundlage dieser stereochemischen Resultate werden mogliche Mechanismen fur diese Umsetzung diskutiert. The Sterochemistry of the Oxidation of Chiral Tertiary Phosphines by Means of Dimethyl Sulfoxide The steric course o…
Triphosphine-supported bimetallic Au(I)-M(I) (M = Ag, Cu) alkynyl clusters.
2014
The reactions of gold acetylides (AuC2R)n with triphosphine ligands PPh2-(CH2)n-PPh-(CH2)2-PPh2 (n = 1, dpmp; 2, dpep) in the presence of M(+) ions (M = Cu, Ag) lead to an assembly of the heterometallic clusters, the composition of which is determined by the steric bulkiness of the alkynyl groups and the flexibility of the phosphine motifs. For R = Ph, an unprecedented hexanuclear complex [Au5Cu(C2R)4(dpmp)2](2+) (1) was isolated, while for the aliphatic alkynes (R = 1-cyclohexanolyl, 2-borneolyl, 2,6-dimethyl-4-heptanolyl) a family of compounds based on a tetrametallic framework was prepared, [Au3Cu(C2R)3(dpmp)](+) (2, R = 1-cyclohexanolyl), [Au3M(C2R)3(dpep)]2(+2) (3, M = Cu, R = 1-cycloh…
Preparation and reactions of 1-methylpyrid-6-one-2-yl compounds of palladium(II) and platinum(II)
1984
Abstract The compounds trans -[MCl{(1-Me)C 5 H 3 (6-O)N- C 2 }(L) 2 ] (M = Pd, Pt; L = PPh 3 , PMe 2 Ph), can be prepared from the reaction of the corresponding 1-methyl-6-chloro-2-pyridylium cationic complexes, trans -[MCl{(1-Me)C 5 H 3 (6-Cl)N- C 2 }(L) 2 ]ClO 4 , with a mixture of acetic acid, ethanol, and triethylamine in the molar ratio M/MeCO 2 H/EtOH/NEt 3 of 1/3/3/4. The rate is slow compared to that of the 1-methyl-2-chloropyridinium cation under similar conditions, and is markedly affected by the steric and electronic effects of the trans -MCl(L) 2 unit. The novel 1-methylpyrid-6-one-2-yl derivatives have been characterized by conventional spectroscopic techniques and by reactions…
Synthetic Endeavors toward Titanium Based Frustrated Lewis Pairs with Controlled Electronic and Steric Properties
2015
A new family of cationic Ti complexes 4′ with a pendant phosphine of general formula [CpCpPTiOAr][BPh4] (Cp = η5-C5H5; CpP = η5-C5H4(CMe2)PR2) has been prepared in four steps from 6,6-dimethylfulvene. These complexes were designed to behave as Ti based frustrated Lewis pairs (FLPs). The key synthetic step is a reduction–oxidation sequence from [CpCpPTiClOAr] complexes 3 using lithium phosphide salts as the reductants and ferricinium tetraphenylborate as the oxidant. Four complexes have been structurally characterized by X-ray diffraction and show elongated Ti–P bonds, above 2.60 A. One complex (4b′: OAr = 2,6-Me2C6H3; PR2 = PCy2) reacted with benzaldehyde to form a typical FLP activation pr…
Synthesis, microwave spectrum, quantum chemical calculations, and conformational composition of a novel primary phosphine, cyclopropylethynylphosphin…
2014
International audience; The microwave spectrum of cyclopropylethynylphosphine, C3H5C≡CPH2, has been investigated in the 26-120 GHz spectral region. The spectrum is dominated by very rich and complex a-type R-branch pile-ups. There must be insignificant steric interaction between the phosphino group and the cyclopropyl ring due to the long distance between these two groups. However, the phosphino group does not undergo free or nearly free internal rotation. Instead, the spectra of two distinct conformers were assigned. Both these two forms have CS symmetry. The symmetry plane bisects the cyclopropyl ring and the phosphino group in both conformers, and the lone electron pair of the phosphino …