117228-07-6

Upstream product

• 117228-69-0 (η-Cp)Fe{P(p-FPh)3}(CO)(Me) 
• 18437-78-0 P(p-C₆H₄F)3 

Relevant academic research and scientific papers

Tertiary phosphine induced migratory carbonyl insertion in cyclopentadienyl complexes of iron(II)

Cyclopentadienyldicarbonylmethyliron, [CpFe(CO)2Me] (1), undergoes migratory carbonyl insertion under the influence of isosteric phosphine ligands P(4-FC6H4)3 and P(4-MeC 6H4)3. The products of the reaction, [CpFe(CO)(COMe)P(4-FC6H4)3] (2a) and [CpFe(CO)(COMe)P(4-MeC6H4)3] (2b), were characterised by X-ray crystallography. In both structures, the iron atom adopts a pseudo octahedral coordination geometry. Fe-P bond distances are the same at 2.1932(8) ? in 2a and 2b, respectively. Thus, contrary to what was expected, X-ray data could not be used to quantitatively differentiate between the two phosphine ligands in 2a and 2b. Therefore, additional spectroscopic techniques such as IR and NMR were employed. Similarly, the Fe-C bond lengths of the carbonyl (Fe-CO) and acetyl (Fe-COMe) are 1.748(3) and 1.955(3) in 2a, and 1.744(3) and 1.951(3) ? in 2b, respectively. The migratory carbonyl insertion was studied by NMR, IR, and UV-vis spectroscopies to determine the mechanism and the rate law. Results from NMR spectroscopy show that the formation of the product is accompanied by oxidation of the corresponding phosphine ligand. An increase in the reactivity of migratory carbonyl insertion for P(4-MeC6H4)3 was observed when the solvent was changed from CH2Cl2 to MeCN. The kinetic data showed that P(4-MeC6H4)3 reacts faster than P(4-FC6H4)3.

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)

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

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

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.