12078-28-3Relevant academic research and scientific papers
A KINETIC STUDY OF THE CLEAVAGE OF THE IRON-CARBON ? BOND IN η5-C5H5Fe(CO)2R BY HALOGENATED ACETIC ACIDS
Luca, Nancy De,Wojcicki, Andrew
, p. 359 - 378 (1980)
The rates of the reaction of η5-C5H5Fe(CO)2R (R = alkyl and aryl) with CF3CO2H to give η5-C5H5Fe(CO)2OC(O)CF3 and RH were investigated in organic solvents, mostly at 25 deg C, by infrared spectroscopic, manometric and volumetric techniques.When R = alkyl, the cleavage in CH2Cl2 is first order in η5-C5H5Fe(CO)2R and first order in the CF3CO2H monomer at acid concentrations 0.1 M, but first order in η5-C5H5Fe(CO)2R and second order in the CF3CO2H monomer at lower acid concentrations.The dependence of the second-order rate constant on R follows the order C6H5 > CH2Si(CH3)3 (>110) > CH3 (32) > n-C4H9 (15) > C2H5 (11) > CH2C(CH3)3 (6.2) > CH2CH2C6H5 (5.3) > CH(CH3)C6H5 (ca. 1.2) CH2C6H5 (1.0) > CH(CH3)2.The isotope effect, kH/kD, for the cleavage of η5-C5H5Fe(CO)2CH3 by CF3CO2H and CF3CO2D is 4.7.Solvent influence on the rate of the Fe-CH3 bond scission in CH2Cl2, CH2ClCH2Cl and C6H6 is very small.A mechanism is proposed which involves the formation of an Fe-H-OC(O)CF3 hydrogen-bridged 1/1 adduct of the reactants in a reversible step.This adduct then affords 5-C5H5Fe(CO)2(R)H> with the assistance of a second molecule of CF3CO2H.Reductive elimination of RH and coordination to iron of CF3CO2- complete the reaction.The corresponding cleavage of a given Fe-R bond by CHCl2CO2H is substantially slower than that by CF3CO2H; for the aryl complexes it follows the order R = p-C6H4CH3 > p-C6H4F > C6H5 > p-C6H4Cl, with ρ ca. -5.4.
Reaction Studies on Heterodinuclear Alkanediyl Complexes: Some Examples of Metalloselectivity
Friedrich, Holger B.,Moss, John R.
, p. 2863 - 2870 (1993)
The reactions of some heterobimetallic alkanediyl complexes of the type with tertiary phosphines, trityl hexafluorophosphate (Ph3CPF6) and halogens were investigated.The reactions of with PPh3 were metalloselective, with the phosphine always attacking the expected metal site, which could be predicted from the reactivities of the corresponding monometallic alkyl or homodinuclear alkanediyl species.The alkanediyl chain length was found not to influence the site of nucleophilic attack.The reactions of with Ph3CPF6 gave the complexes PF6, where the β-CH unit is believed to be weakly bonded to both metal centres.The reaction of (n = 4 or 6) with the trityl salt was not metalloselective, and gave a mixture of equal amounts of n-2>Ru(CO)2(cp)>PF6 and n-2CHCH2>Ru(CO)2(cp)>PF6.In contrast, gave only W(CO)3(cp)>PF6.Metalloselectivity was observed for the reaction of with HCl, which gave cleavage of the W-C bond.In contrast, the reaction of with I2 resulted in cleavage of both metal-alkyl bonds.The reactions of with PPh3 to give Mo(CO)3(cp)> and Mo(PPh3)(CO)2(cp)> are also reported.
Fe:Co/TiO2 bimetallic catalysts for the Fischer-Tropsch reaction: Part 4: A study of nitrate and carbonyl derived FT catalysts
Duvenhage,Coville
, p. 230 - 239 (2005)
A series of Fe:Co bimetallic catalysts supported on TiO2 were prepared by precipitation from nitrate salts and by impregnation from metal carbonyl complexes. These Fe:Co materials were characterized by a range of techniques including BET, temperature programmed reduction (TPR) and CO chemisorption, and their Fischer-Tropsch (FT) activity was evaluated in a series of fixed bed reactors (220 °C, 10 bar, 2H2:1CO, 350 h -1, 200 h). Important observations from the study are (i) both preparation technique yield catalysts in which the Fe:Co/TiO2 has lower activity than the equivalent Co/TiO2 catalyst and (ii) selectivity patterns are similar to a Co/TiO2 catalyst but indicate the impact of Fe on the system. Methane levels produced with the precipitated catalysts are high (20 wt%) while levels for the most active carbonyl bimetallic catalysts are lower (10 wt%). The impregnated catalysts produced from metal carbonyl precursors proved to be the better long chain hydrocarbon producers and olefin producers than the precipitated catalysts produced from metal nitrate precursors.
Indium monohalide insertion reactions into metal-metal bonds. Crystal structure of 2>
Clarkson, L. M.,Norman, N. C.,Farrugia, L. J.
, p. C10 - C15 (1990)
The reaction between InCl and affords 2>, 6a which has been characterised as a THF adduct 2>, 10, by X-ray crystallography.An additional complex, 2>-, 11, is also formed in this reaction.Similar products are reported for reactions involving (M = Cr, W).The reaction between InCl and affords 2>, 17, and >, whilst that between InI and affords 2>, 19.
The Carbalkoxymethyl Ligand on (η-C5H5)(CO)FeCH2CO2CH3 as a CO-Derived C2 Template for Generating C2 Organic Ligands and Molecules
Crawford, Edward J.,Lambert, Carol,Menard, Kevin P.,Cutler, Alan R.
, p. 3130 - 3139 (1985)
The carbalkoxymethyl ligand on Cp(CO)FeCH2CO2R (7) (R = CH3, CH2CH3) serves as a C2 template for generating other C2-coordinated ligands and organic molecules.In this study 7 is procured by acid isomerization of the alkoxyacetyl complexes Cp(CO)FeCOCH2OR (5), which are obtained by P(OCH3)3-induced CO-insertion on Cp(CO)2FeCH2OR. (Overall, the carbalkoxymethyl ligand on 7 derives from two CO groups on Cp(CO)3Fe(1+)).A mechanism for this alkoxyacetyl-carbalkoxymethyl ligand isomerization is advanced whereby protonation of 5 generates a ligated ketene intermediate that regioselectively adds alcohol and gives 7.In excess acid either 5 or 7 quantitatively releases acetic acid ester, a selective generation of this C2 organic from CO.The carbalkoxymethyl ligand on 7 is activated as a hydride acceptor by converting it to the (dialkoxycarbenio)methyl salt Cp(CO)FeCH2C(OR)2(1+) (8). (Interestingly, 8 cannot be generated from the alkoxycarbene system Cp(CO)FeC(OR)CH2OR(1+) (6).) BH4(1-) converts 8 into a mixture of η2-ethylene and η1-ethyl complexes of Cp(CO)Fe, whereas (sec-Bu)3BH(1-)Li(1+) generates the corresponding η2-ethyl vinyl ether and η1-formylethyl compounds.The conversion of these latter two into acetaldehyde is discussed.
Two heterodinuclear NiFe-based sulfenate complexes mimicking an S-oxygenated intermediate of an O2-tolerant [NiFe]-H2ase: Synthesis, structures, and reactivity
Song, Li-Cheng,Chen, Wei,Feng, Li
, p. 14015 - 14023 (2020)
The synthetic modelling of the S-oxygenated intermediate of an O2-tolerant [NiFe]-H2ase has proven to be greatly challenging. Treatment of 1,4-bis(2-mercapto-2-methylpropyl)-1,4-diazacycloheptane with Ni(acac)2 gave dithiolate complex [1,4-bis(2-mercapto-
Photoinduced Carbon Monoxide Release from Half-Sandwich Iron(II) Carbonyl Complexes by Visible Irradiation: Kinetic Analysis and Mechanistic Investigation
Jiang, Xiujuan,Chen, Limei,Wang, Xiu,Long, Li,Xiao, Zhiyin,Liu, Xiaoming
, p. 13065 - 13072 (2015)
Three half-sandwich iron(II) complexes, [Fe(η5-Cp)(cis-CO)2X] (X-=Cl-, Br-, I-), were synthesized and characterized. The kinetics of the CO-releasing behaviour of these complexes upon illumination by visible irradiation in various media was investigated. Our results indicated that the CO release was significantly affected by the auxiliary ligands. Of the three light sources used (blue, green, and red), blue light exhibited the highest efficiency. In the photoinduced CO release, the solvents and exogenous nucleophiles in the media were involved, which allowed their CO-releasing reaction to comply with pseudo first-order model rather than the characteristic zero-order model for a photochemical reaction. In aqueous media (D2O), an intermediate bearing the core of {FeII(cis-CO)2} involving cleavage of cyclopentadiene was detected. Despite the non-absorption of the red light, its illumination combined with nucleophilic substitution did cause considerable CO release. Assessment of the cytotoxicity of the three complexes indicated that they showed good biocompatibility.
THE REACTIONS OF 4-n(CNMe)n> (n=0-4) COMPLEXES WITH HALOGENS AND MERCURY(II) SALTS
Kumar, Rajesh,Manning, A. R.,Murray, Paul T.
, p. 53 - 66 (1987)
Halogens, X2, and HgY2 (X=Cl, Br, I; Y=X, F, NO3, BF4) cleave the metal-metal bonds in 4-n(CNMe)n> complexes (n=0-4).Typically, e.g. when n=2, X2 electrophiles give (a) and X (b) in relative yields which depend on X, the reaction solvent and n, but HgY2 give equimolar amounts of (c) and only.Hg(CN)2 reacts more slowly than other HgY2, and does not react at all.It is suggested that the reactions which give rise to products of type (a), (b) or (c) are all two-electron oxidations which proceed by way of adducts containing μ-CA->X2 or μ-CA->HgX2 groups (CA=CO or CNMe).One of these adducts has been isolated, namely 2>*CHCl3.
Further reactions of (MLn=Fe(η-C5H5)(CO)2, Re(CO)5) with organic electrophiles
Busetto, L.,Bordoni, S.,Zanotti, V.
, p. 125 - 132 (1988)
Reaction of FpC(S)SMLn (Fp=Fe(η-C5H5)(CO)2; MLn=Fp (1a), Re(CO)5 (1b)) with MeC(O)Cl affords Cl and LnMSC(O)Me (3); 1a reacts with (CF3CO)2O to yield CF3CO2 and FpSC(O)CF3 (5).In both cases the reactions have been shown to occur via the unstable S-acylated intermediates SMLn>+ (R=CF3, Me).Alkylation of 1a with RBr (R=Me, Et, CH2Ph, CH2CHCH2) or CF3SO2OR (R=Me, Et) followed by treatment of the stable S-alkylated derivatives + with I- provides a useful alternative method for the synthesis of a variety of FpC(S)SR.
Probing the electron transfer mechanism of the half-sandwich iron(II)-carbonyl complexes and their catalysis on proton reduction
Rong, Bingying,Zhong, Wei,Gu, Erxing,Long, Li,Song, Lijuan,Liu, Xiaoming
, p. 27 - 35 (2018)
The electrochemical behaviors of three half-sandwich iron(II) complexes, [CpFe(CO)2X] (Cp = cyclopentadienyl, 1: X = Cl; 2: X = Br; 3: X = I) were investigated. For the three complexes, two reduction processes at ca. ?1.3 V and ?2.0 V were observed. They are assigned to the reductions of Fe(II) → Fe(I) couple and the reduction of the dimer, [CpFe (μ-CO)(CO)]2 (Fp2), which formed via the dimerization of the neutral intermediate “CpFe(CO)2” (Fp) generated from the first reduction, respectively. Our results ruled out the possibility of two-electron reduction for the first process. Using stop-flow infrared spectroscopic technique (SFIS) allowed us to trace the rapid chemical reactions and the first-order reaction rate constants for the formations of both Fp and Fp2 were derived as 0.27 and 0.43 s?1, respectively. Both complexes 1 and Fp2 could be reduced by LiHBEt3. In the reduction, ligand exchange reaction occurred between the chloride and hydride, which was evidenced by the observation the absorption bands of [CpFe(CO)2H] (FpH). Their reduction reactions abided first-order model for the complex and the reducing agent. By assuming that equal moles of the complex and the reducing agent were used in the reduction, a rate equation was established. Again, the SFIS technique was employed to follow the reductions and linear plots were observed to give the rate constants as 14 and 18 mol?1 L s?1, respectively. The catalysis on proton reduction of the complexes was also examined. Sufficient experimental evidences in our work and the analysis of literature data suggested strongly that the catalytic species was not the neutral species Fp. Instead the anion, FpX?, was responsible for the catalysis. The poor performance in catalysis of these complexes resulted from the competing reaction coupled to the first reduction, loss of the halide upon reduction. The resultant neutral species, Fp dimerized rapidly into Fp2.
