18475-06-4Relevant articles and documents
Effect of fluorine and trifluoromethyl substitution on the donor properties and stereodynamical behaviour of triarylphosphines
Howell, James A. S.,Fey, Natalie,Lovatt, Jonathan D.,Yates, Paul C.,McArdle, Patrick,Cunningham, Desmond,Sadeh, Einat,Gottlieb, Hugo E.,Goldschmidt, Zeev,Hursthouse, Michael B.,Light, Mark E.
, p. 3015 - 3028 (2007/10/03)
A series of 2-, 3- or 4-trifluoromethyl substituted triarylphosphines and their oxide, chalcogenide and Fe(CO)4 derivatives have been prepared and characterised spectroscopically and crystallographically. Electronic effects of CF3 su
Reactivity of Fe(CO)4(H)MPh3 (M = Si, Ge) and mechanism of substitution by two-electron-donor ligands: Implications for the mechanism of hydrosilylation of olefins catalyzed by Fe(CO)5
Bellachioma, Gianfranco,Cardaci, Giuseppe,Colomer, Ernest,Corriu, Robert J. P.,Vioux, André
, p. 519 - 525 (2008/10/08)
cis-Fe(CO)4(H)MPh3 (M = Si, Ge) complexes undergo carbonyl displacement with nucleophilic ligands (phosphines, phosphites) to give Fe(CO)3(H)(L)MPh3. With M = Si the geometry of these complexes depends on the nature of the solvent; in nucleophilic solvents the mer-OC-6-43 isomer is formed, while in nonnucleophilic solvents the mer-OC-6-23 isomer is obtained (the cis positions of H and Si are retained). These two isomers undergo concerted reductive elimination of silane with PPh3. The mer-OC-6-43 isomer reacts 183 ± 19 times faster than the mer-OC-6-23 isomer in toluene at 26.0°C, giving the same 16-electron intermediate; the calculated equilibrium constant for the interconversion of OC-6-43 and OC-6-23 is 823 ± 192 at 26.0°C in toluene. Owing to the strong acidity of Fe(CO)4(H)MPh3 (pKa estimated as 3CN) and of Fe(CO)3(H)(PPh3)MPh3 (pKa estimated as ≤8.94 in CH3CN), reaction with basic two-electron-donor ligands [P(alkyl)3, P(cycloalkyl)3, NR3] leads to the formation of the anionic trigonal-bipyramidal complexes [Fe(CO)4MPh3]- and [Fe(CO)3(L)MPh3]-. cis-Fe(CO)4(H)SiPh3 reacts with isoprene to give [Fe(CO)4SiPh3]2; this reaction is not observed with Fe(CO)3(H)(L)SiPh3. The versatile reactivity of these complexes sheds some light on the mechanism of hydrosilylation of olefins and conjugated dienes. Under thermal conditions previous coordination of the olefin to the metal in this reaction seems to be excluded.
Preparation and Spectroscopic Characterization of trans-Fe(CO)3L1L2 (L1, L2 = Phosphine or Phosphite)
Inoue, Hidenari,Kuroiwa, Takeshi,Shirai, Tsuneo,Fluck, Ekkehard
, p. 641 - 646 (2007/10/02)
The 57Fe Moessbauer spectra of mixed ligand complexes of the type trans-Fe(CO)3L1L2 (L1 = triphenylphosphine or triphenylphosphite and L2 = phosphine or phosphite) show a quadrupolesplitting doublet typical of the disubstituted iron carbonyls in trigonal bipyramidal symmetry.The inverse linear dependence of the isomer shifts on the CO stretching frequencies is interpreted on the basis of the strengthening triple-bond nature of the carbonyl ligands with increasing iron-to-phosphorus ?-back donation.A linear correlation, with a positive slope, between the isomer shifts and the quadrupole splittings has revealed that the phosphorus-to-iron ?-donation is offset by the iron-to-phosphorus ?-back donation.A corrlation between the coordination shifts and the isomer shifts demonstrates that the iron-to-phosphorus ?-back donation plays an important role in the Fe-P bond.The relatively large coupling constant of 2J(P,P) reflects a strong interaction between trans-phosphorus ligands through the P-Fe-P bond. - keywords: (Phosphine/Phosphite)tricarbonyliron, Moessbauer Spectra, IR Spectra, 31P NMR Spectra
Solution Structure and Dynamic Behaviour of two Isomers of (R = Me, Et, or Ph) Derivatives
Aime, Silvio,Botta, Mauro,Gambino, Olimpia,Gobetto, Roberto,Osella, Domenico
, p. 1277 - 1282 (2007/10/02)
The reaction between and P(OR)3 (R + Me, Et, or Ph) in the presence of the bimetallic catalyst affords two 1,2,3-trisubstituted isomers which rapidly interconvert at room temperature on the n.m.r. time-scale.The solution structures and dynamics have been elucidated for both isomers by means of variable-temperature 31P and 13C n.m.r. studies.In polar solvents the major isomer shows a -like structure whereas the minor one contains only terminally bonded CO groups.The observation of three equally intense carbonyl resonances in the low-temperature-limiting spectra (R = Me or Et) su pports a D3 structure for this isomer.The equilibration of axial CO ligands occurs readily as the temperature is increased; this rearrangement may be ascribed to the motion of the Fe3 triangle inside the polyhedral cloud of ligands or alternatively to an interconversion between a left-hand screw with a right-hand screw.
Low temperature photochemistry of . Stabilization of an intermediate photoproduct in a decomposition reaction
Dijk, Hans K. van,Stufkens, Derk J.,Oskam, Ad
, p. 227 - 238 (2007/10/02)
The complex (I), a photoproduct from , is itself photolabile.The UV, IR, resonance Raman spectra of I are described and used for the interpretation of its photochemical behaviour.Irradiation of I in its low-energy MLCT band in the presence of PR3 or a N-donor ligand (L) causes photosubstitution of the last CO ligand of the Fe(1)-bipy moiety, giving the thermally unstable complex (II).Because of this thermal lability of the primary photoproduct, the photochemical reactions were performed in 2-Me-THF at 133 K.The complexes II with L=PR3 decomposed thermally above 200 K, but when L was an N-donor ligand, partial decomposition took place at 133 K.The nature of these decomposition products depend on L.It is suggested that the photochemical reactions occur from a reactive 3LF state after intersystem crossing from the 1MLCT state.Evidence for a close lying 1LF state comes from the resonance Raman spectrum upon 458 nm excitation, which shows anti-resonance Raman effects for all the vibrations.
Infrared, (57)Fe Moessbauer, and (31)P NMR Spectroscopic Characterization of Fe(CO)4L (L = Phosphine and Phosphite)
Inoue, Hidenary,Nakagome, Takashi,Kuroiwa, Takeshi,Shirai, Tsuneo,Fluck, Ekkehard
, p. 573 - 578 (2007/10/02)
A series of trigonal bipyramidal Fe(CO)4L complexes has been prepared and characterized by infrared, (57)Fe Moessbauer and (31)P NMR spectroscopy.A linear correlation, with a negative slope, between the CO stretching frequencies and the isomer shifts demonstrates that the triple bond nature of the carbonyl ligands is strengthened with increasing iron-to-phosphorus back donation.The linear dependence of the quadrupole splittings on the isomer shifts with a positive slope has revealed that the ?-donor capability of the phosphine or phosphite ligand is offset by the ?-acceptor capability.The formation of Fe(CO)4L complexes from the corresponding free ligands is accompanied by a downfield shift of (31)P NMR chemical shifts.The coordination shifts are linearly correlated with the Moessbauer isomer shifts. - Phosphinetetracarbonyliron, Phosphitetetracarbonyliron, IR Spectra, (31)P NMR Spectra, (57)Fe Moessbauer Spectra
Substitutional reactivity of dodecacarbonyltrimetal complexes of iron and osmium
Shojaie, Abdolrasul,Atwood, Jim D.
, p. 187 - 190 (2008/10/08)
The kinetics of the substitution reactions of Fe3(CO)12 and Os3(CO)12 have been investigated for L = PPh3, PBu3, P(OPh)3, and P(OMe)3 in hydrocarbon solution. The substitution of the iron cluster leads to both substitution and fragmentation products with a very small dependence on the entering ligand, typical of a CO dissociative interchange mechanism. Substitution of Fe3(CO)11PPh3 leads only to fragmentation at a rate which is faster than substitution on Fe3(CO)12. Substitution on Os3(CO)12 occurs in an entering ligand independent reaction to Os3(CO)9L3. The reactivities of these clusters are compared to the ruthenium analogue and to the mononuclear complexes M(CO)5.
Rates of substitution reactions of derivatives of iron pentacarbonyl, Fe(CO)4L and Fe(CO)3L2 (L = PPh3, AsPh3, P(OPh)3): Application of crystal field activation energies to organometallic complexes
Modi, Sandeep P.,Atwood, Jim D.
, p. 26 - 28 (2008/10/08)
Dissociation of ligands from Fe(CO)3L2 and Fe(CO)4L (L = PPh3, P(OPh)3, AsPh3) has been investigated by reaction with carbon monoxide. These complexes are relatively inert, requiring temperatures considerably in excess of 100°C. The relative inertness of 18-electron complexes of iron is considered. The order of ligand lability from Fe(CO)3L2 is AsPh3 > PPh3 > P(OPh)3, which apparently represents the general bond strength to low-valent metal centers.
Paramagnetic Organometallic Molecules. 13. Electron-Transfer-Catalyzed Reactions of Polynuclear Metal Carbonyls: Reactions of R2C2Co2(CO)6
Arewgoda, Malini,Robinson, Brian H.,Simpson, Jim
, p. 1893 - 1903 (2007/10/02)
Polynuclear metal carbonyls are shown to be suitable substrates for rapid electron-transfer-catalyzed (ETC) reactions that offer a new convinient method for the synthesis of many carbonyl derivatives.The factors that influence the applicability and yields of these reactions are discussed and examples with a variety of nucleophiles and substrates given.The distinction between electron-induced nucleophilic substitution (EINS) and ETC reactions is emphasized.ETC reactions of R'RC2Co2(CO)6 with MeCN and other Lewis bases using both electrolytic and chemical reductants are described in detail, in particular those where R' = R = CF3.The yields of the new products (CF3)2C2Co2(CO)5L , (CF3)2C2Co2(CO)4L2 , and (CF3)2C2Co2(CO)3L3 are virtually quantitative, with reaction times no longer than 5 min.In most cases reaction is over in 1 min at 293 K.Yields from ETC reactions with other R'RC2Co2(CO)6 compounds are variable but can be correlated with the lifetime of the radicals anions.Spectroscopic data characterized the phosphite or phosphine ligand as having an axial conformation in R2C2Co2(CO)5L complexes, but the X-ray structure of (CF3)2C2Co2(CO)5(MeCN) shows that the MeCN is equatorial.Steric factors are believed to account for this.However, the MeCN ligand is very labile in solution, and the electrochemistry of the MeCN adduct is characterized by abnormal limiting currents at 293 K that are absent at lower temperatures.The compound (CF3)2C2Co2(CO)5(MeCN) crystallizes in the space group Pna21; a = 15.794 (5) Angstroem, b = 9.803 (3) Angstroem, c = 10.936 (4) Angstroem, Z = 4, V = 1693.4 Angstroem3.
METAL DIMERS AS CATALYSTS. III. THE REACTION BETWEEN Fe(CO)5 AND GROUP V DONOR LIGANDS IN THE PRESENCE OF 5-C5H4R)Fe(CO)2>2 (R = H, Me) AND 5-C5Me5)Fe(CO)2>2 AS CATALYST
Albers, Michel O.,Coville, Neil J.,Singleton, Eric
, p. 261 - 266 (2007/10/02)
The reaction between Fe(CO)5 and Group V donor ligands L, (L = PPh3, AsPh3, SbPh3, PMePh2, PMe2Ph, AsMe2Ph, P(C6H11)3, P(n-Bu)3, P(i-Bu)3, P(OPh)3, P(OEt)3, P(OMe)3) in the presence of 5-C5H4R)Fe(CO)2>2 (R = H, Me) or 5-C5Me5)F
