117228-04-3Relevant academic research and scientific papers
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°.
