117227-98-2Relevant academic research and scientific papers
Alkylation and aldol reactions of acyl and phosphine ligand in (η5-C5H5)Fe(CO)(CH3PPh2)(COCH2R)
Stepowska, Halszka,Zamojski, Aleksander
, p. 221 - 228 (1993)
The effect of replacement of triphenylphosphine in CpFe(CO)PPh3(COR) by methyldiphenylphosphine on the reactivity of the acyl ligand attached toFe has been investigated.Reactions of anions generated from complexes (η5-C5H5)Fe(CO)(CH3PPh2)COCH3 (5) and (η5-C5H5)Fe(CO)(CH3PPh2)COC2H5 (6) with a variety of electrophilic reagents gave mixtures of diastereo- and regio-isomeric products.The proportion of these was found to be independent of the type of base used for deprotonation but dependent on the stoichiometric base-to-complex ratio.The product of benzylation 12gave methyl 3-phenylpropionate after decomplexation with NBS in methanol.
Metallacycle formation through the linking of an alkyne with phosphido and acetyl groups at an iron centre: X-ray structure of (Cp = η5-C5H5)
Adams, Harry,Bailey, Neil A.,Blenkiron, Peter,Morris, Michael J.
, p. 73 - 82 (2007/10/02)
The diphenylphosphine ligand of (Cp = η5-C5H5) can be deprotonated with DBU (DBU = 1,8-diazabicycloundec-7-ene) or n-butyllithium; subsequent alkylation with RI (R = Me, Et) gives the complexes . Reaction of the anionic phosphido complex with the electrophilic alkyne methyl propiolate (HCCCO2Me) followed by reprotonation with CH3COOH gives the vinylphosphine complex , whereas a similar reaction sequence with dimethyl acetylenedicarboxylate (DMAD, MeO2CCCCO2Me) produces two isomers of the complex , in which linking of the alkyne with both the phosphido and acetyl ligands has occurred to form a six-membered metallacycle. The structure of one of the two isomers has been determined by X-ray diffraction and shows that the metallacyclic ring is bound to the iron atom through the phosphorus and the carbonyl oxygen of the acetyl group, and adopts a boat conformation in the solid state.
Comparison of the dynamics and thermodynamics of the redox-promoted carbonylation of (η-Cp)(CO)(L)FeMe in methylene chloride and acetonitrile. Applications of the Quantitative Analysis of Ligand Effects (QALE)
Woska, David C.,Wilson, Matthew,Bartholomew, Joshua,Eriks, Klaas,Prock, Alfred,Giering, Warren P.
, p. 3343 - 3352 (2008/10/08)
The redoz-catalyzed carbonylations of 19 complexes, (η-Cp)(CO)(L)FeMe (L = PMe3, PPhMe2, PEt3, PPh2Me, PEt2Ph, PPh2Et, P(i-Bu)3, P(p-Me2NC6H4)3, P(p-MeOC6H4)3, P(p-MeC6H4)3, PPh3, P(p-FC6H4)3, P(p-ClC6H4)3, P(p-CF3C6H4)3, PPh2Cy, PPh2-t-Bu, P(i-Pr)3, PPhCy2, PCy3), in acetonitrile have been studied by cyclic and square-wave voltammetry coupled with computer simulation methods. The mechanism appears to involve oxidation of (η-Cp)(CO)(L)FeMe and rapid formation of (η-Cp)(AN)(L)FeCOMe+ followed by rate-limiting reaction of (η-Cp)(AN)(L)FeCOMe+ with CO. Quantitative analysis of the ligand effect data shows that the second-order transformation of (η-Cp)(CO)(L)FeMe+ to (η-Cp)(AN)(L)FeCOMe+ is accelerated by poorer electron donor ligands and inhibited by the larger ligands. The first-order back-reaction of (η-Cp)(AN)(L)FeCOMe+ to (η-Cp)(CO)(L)FeMe+, in contrast, is relatively insensitive to the electron-donor capacity and the size of L. The second-order reaction between (η-Cp)(AN)(L)FeCOMe+ and CO is accelerated by better electron-donor ligands; the steric profile is complex and shows sequential regions of no steric effects, steric acceleration, and steric inhibition. The results of the studies are compared with those obtained when methylene chloride is the solvent.
Studies of the oxidatively promoted carbonylation of η-Cp(CO)(L)FeMe in methylene chloride. Applications of the quantitative analysis of ligand effects
Prock, Alfred,Giering, Warren P.,Greene, Jack E.,Meirowitz, Randy E.,Hoffman, Steven L.,Woska, David C.,Wilson, Matthew,Chang, Richard,Chen, Jianxiang,Magnuson, Roy H.,Eriks, Klaas
, p. 3479 - 3485 (2008/10/08)
The carbonylation of η-Cp(CO)(L)FeMe+ (L = PPhMe2, PEt3, PPh2Me, PEt2Ph, PPh2Et, P(p-MeOPh)3, P(p-MePh)3, PPh3, P(p-FPh)3, P(p-ClPh)3, P(p-CF3Ph)3, PPh2Cy, PPhCy2, PCy3) in methylene chloride has been studied by a combination of kinetic, stereochemical, isotopic labeling, ligand effect, and electrochemical experiments. Redox-catalyzed (ferrocenium tetrafluoroborate) carbonylation of (+)-η-Cp-(CO)(PPh3)FeMe gives racemic η-Cp(CO)(PPh3)FeCOMe. The results of control experiments suggest that the racemization is attributable to the configurational instability of η-Cp(CO)(PPh3)FeMe+. The redox-catalyzed carbonylation of η-Cp(CO)(PPh3)FeMe under 1 atm of 13CO affords η-Cp(13CO)(PPh3)FeCOMe. The rate of the electrochemically promoted carbonylation of η-Cp(CO)(L)FeMe is independent of the concentration of the starting complex, carbon monoxide, and the supporting electrolyte, tetrabutylammonium hexafluorophosphate (TBAH). Kinetic data for the carbonylation of η-Cp(CO)(L)FeMe+, which is first order in complex and zero order in carbon monoxide, were obtained by computer simulation analysis of cyclic and square-wave voltammetry data. Analysis of the data for L = P(p-ClPh)3 and P(p-CF3Ph)3 reveals enthalpies of activation (ΔH≠ = 7.8 ± 2.0,6.7 ± 0.8 kcal/mol) and entropies of activation (ΔS≠ = -23 ± 7, -25 ± 3 eu), respectively. Quantitative analysis of the ligand effect (QALE) data shows that the carbonylation of η-Cp(CO)(L)FeMe+ is accelerated by poorer electron-donor ligands; the steric profile shows a region of steric inhibition for small ligands with a steric threshold at 150° after which the rate of reaction rises rapidly. Analysis of the E° values for the η-Cp(CO)(L)FeMe/η-Cp(CO)(L)FeMe+ couple also reveals a steric threshold at 150°.
Separation of phosphorus(III) ligands into pure σ-donors and σ-donor/π-acceptors: Comparison of basicity and σ-donicity
Rahman, Md. Matiur,Liu, Hong-Ye,Eriks, Klaas,Prock, Alfred,Giering, Warren P.
, p. 1 - 7 (2008/10/08)
The separation of phosphorus(III) ligands into two distinct groups identified as pure σ-donor ligands and σ-donor/π-acceptor ligands for the acetyl and methyl complexes, (η-Cp)FeL(CO)COMe, (η-Cp′)FeL-(CO)COMe (Cp′ = MeC5H4), and (η-Cp)FeL(CO)Me, is accomplished by correlation of the terminal carbonyl stretching frequencies with the EL°′ values. The basicity (pKa value of HPR3+) is related primarily to the σ-donicity (the ability of a ligand to donate σ-electrons to a transition metal) and to a lesser degree to the size of the ligand. We conclude that pKa values are reasonable measures of the σ-donicity for those ligands that are pure σ-donor ligands; a better measure are the χ values for those ligands that are pure σ-donors for both the iron complex and LNi(CO)3.
