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Iron element was extracted from the powder scrap of Nd-Fe-B sintered magnets via the carbonylation reaction with sulfur as a catalyst. The resultant carbonyl complex was Fe(CO)5 and the yield was evaluated to be ～56% by energy dispersion X-ray analysis. After applying the hydrogenation disproportionation treatment on the powder scrap, the extraction rate for Fe element was considerably accelerated on the resultant α-Fe/Fe2B/NdH2 (or neodymium oxides) nanocomposite powders to produce Fe(CO)5 in a maximum yield of ～92%.

Complexes using trifluorovinylferrocene and 1,1′-bis(trifluorovinyl)ferrocene as ligands can be obtained by the reaction with a series of fragments of transition metal complexes. Formation of [Pt(η2-trifluorovinylferrocene)(PPh3)2] (1), [{Pt(PPh3)2}2(η2-1,1′-bis(trifluorovinyl)ferrocene)] (2) and [Pt(η2-1,1′-bis(trifluorovinyl)ferrocene)(PPh3)2] (3) were achieved by ligand substitution in [Pt(η2-CH2?=?CH2)(PPh3)2]. Treatment of eneacarbonyldiiron with trifluorovinylferrocene provided [Fe(CO)4(η2-trifluorovinylferrocene)] (4). Photolytically activated reactions of [MnCp(CO)3] and [MnCp′(CO)3] (Cp′?=?C5H4CH3) afforded [MnCp(CO)2(η2-trifluorovinylferrocene)] (5a) and [MnCp′(CO)2(η2-trifluorovinylferrocene)] (5b) respectively. [Ni(η2-trifluorovinylferrocene)(Cy2P(CH2)2PCy2)] (6) could be obtained by reaction with [Ni(COD)2] and Cy2P(CH2)2PCy2. Furthermore the C[sbnd]F bond activation by oxidative addition in the presence of lithium iodide yielding two isomers of [PtI{η1-difluorovinylferrocene}(PPh3)2] (7a/7b) is presented. Molecular structures of 1, 4 and 7a were elucidated using X-ray single crystal diffraction. The spectroscopic and structural data of these complexes prove the powerful π acceptor abilities of these ligands.

The transient infrared absorption spectra of the coordinatively unsaturated Fe(CO)x species generated via excimer laser photolysis of gas phase Fe(CO)5 are presented and discussed.The photofragments produced upon 351, 248, and 193 nm photolysis are characterized.Fe(CO)3 and Fe(CO)4 are produced upon 351 nm photolysis.In addition to these two fragments, Fe(CO)2 is produced on 248 nm photolysis.The gas phase structures of these Fe(CO)x fragments are observed to be compatible with those determined from condensed phase experiments.The coordinatively unsaturated photofragments are typically formed with significant amounts of internal excitation.The rate constants for reaction of Fe(CO)4, Fe(CO)3, and Fe(CO)2 with CO are (3.5+/-0.9)X1010, (1.3+/-0.2)X1013, and (1.8+/-0.3)X1013 cm3 mol-1 s-1, respectively.The large difference in the magnitude of the rate constant for reaction of Fe(CO)4 vs Fe(CO)3 and Fe(CO)2 with CO is rationalized in terms of the spin states of the reactants and products.Following 193 nm photolysis, a new product is observed which is tentatively assigned as an excited electronic state of Fe(CO)3.A photochemical scheme which accounts for all observed products is presented.

Two iron complexes, cis-(CO)4Fe[C(O)C(O)CH3](CO2CH3) (1a) and cis-(CO)4Fe[C(O)CO2-CH2] [C(O)CH2] (3), are reported. Each complex can be considered as a λ-keto ester with a metal atom inserted into the chain linking its two organic groups. 1a is the only one found to evolve thermally, similarly to organic λ-keto esters, into the methoxy metallalactone (CO)4FeC(O)C(CH3)(OCH3)OC(O) (2a). This reaction is not reversible and does not require any acid or alkaline catalysis. The process does not result from a spontaneous dissociation of the methoxycarbonyl ligand of la but from an associative intra or intermolecular mechanism. A similar process can also be induced by pronucleophile reagents, and it affords a series of substituted metallalactones: (CO)4FeC(O)C(CH3)(Nu)OC(O) (Nu = OCH3 (2a), OC2H5 (2b), SC2H5 (2c), P(C6H5)2 (2d), P(C6H11)2 (2e)). Complex 2e has been characterized structurally. These substituted lactones are formed by nucleophilic attack of the reagent at the pyruvyl β-carbonyl followed by carbonylate attack on the alkoxycarbonyl ligand.

The kinetics of the stoichiometric reaction of methyltrialkylammonium cations with nucleophilic metal carbonylate anions was investigated in terms of its relationship to a new catalytic methanol homologation method. At high temperatures and pressures of H2 and CO, a methyl group from each cation is incorporated into methane or ethanol. In the ionizing solvent, N-methylpyrrolidinone, the reaction using iron tetracarbonyl hydride anion is first order in both the methylammonium cation and iron carbonylate anion concentrations and zero order with respect to the partial pressures of hydrogen or carbon monoxide. The enthalpy and entropy of activation, in the temperature range of 180-210°C, are 44 kcal/mol and +17 eu, respectively. The second-order rate constants exhibit a primary kinetic salt effect, increasing with decreasing salt concentration. The rate constants also increased with decreasing dielectric constant of the solvent. The data are consistent with methyl group transfers (SN2) between ions as the rate-limiting step. At 200°C and 245 atm (3:1 CO/H2) the second-order rate constants, 2.0 × 10-4 M-1 s-1 for HFe(CO)4-, 5.3 × 10-4 M-1 s-1 for Mn(CO)5-, are a measure of the nucleophilicities of these carbonylates toward tetramethylammonium ion. In the case of the manganate system, the product selectivity (ethanol vs. methane) was found to be independent of H2 or CO partial pressure between 61 and 184 atm but slightly dependent on the concentration of Mn(CO)5-. These factors are discussed in terms of reaction mechanism.

A new and feasible method to prepare long and well-oriented SWNTs on substrates in large scale is developed by applying a floating catalyst chemical vapor deposition (CVD) process. The catalysts for SWNT growth come from the decomposition of iron pentacarbonyl (Fe(CO)5) formed in situ from the reaction of iron powder and carbon monoxide gas. The growth of SWNTs is found to happen both on the substrate and in the gas flow. Both long and short nanotubes are formed on the substrates but only the long SWNTs are aligned by gas flow. The growth direction and the density of the long SWNTs can be easily controlled. In addition, long SWNTs can be cut and patterned using photolithography and water plasma etching techniques, offering a way to prepare patterned SWNTs with controllable orientation, density and lengths for various applications.

The stable anion - (2) is methylated at the metal by reaction with MeSO3CF3 at -50 deg C to give (CO)4Fe(Me)(COCO2Et) (3) characterized in situ by 1H and 13C NMR; at -30 deg C

The synthesis and chemical behaviour of the new iron-rhodium anionic carbonyl clusters x>- (x=10 or 11), 2-, 2-, and - are reported.Low-temperature mu

Treatment of with (thf=tetrahydrofuran) affords , the structure of which has been determined by an X-ray diffraction study.The crystals are orthorhombic, space group Pnam (non-standard setting of Pnma, No. 62), in a unit cell with a=16.851(12), b=9.338(5), c=11.566(9) Angstroem, U=1820(2) Angstroem3 at 220 K, and Z=4.The structure was solved to R 0.057 (R' 0.058) from 1860 observable independent reflections 3.0?(l)>.The molecule possesses Cs symmetry; one terminal carbonyl ligand on each of the metal atoms, together with the Rh-Mn bond , define the mirror plane.The cyclopentadienyl ligand on the Mn atom is in a trans relationship to the pentamethylcyclopentadienyl ligand on the Rh atom and both lie astride (perpendicular to) the mirror plane.The two other carbonyl ligands are terminal to the Mn atom but are strongly semi-bridging to the Rh atom and define planes which are nearly perpendicular to the mirror plane.A distortion of the Rh-C5 geometry towards a 'diolefin' type attachment is discussed.Reaction of with in thf affords the compounds and .The latter is also formed, together with 3-CO)(μ-CO)2(CO)3(η-C5Me5)2>, on treatment of with excess .The trirhodium complex 3-CO)(μ-CO)2(η-C5Me5)2> was obtained in high yield by pyrolysis of acd undergoes dynamic behaviour in solution.Protonation of the trirhodium cluster of affords quantitatively the cation 3-CO)(μ-CO)2(η-C5Me5)3>(1+) which can be deprotonated with NaOMe in MeOH.

A brief summary of the IR photochemistry of matrix isolated Fe(CO)4 is presented.We explain how some of the processes can be rationalised on the distortion octahedron model, originally developed by considering the Jahn-Teller distortion of Fe(CO)4.An analogy is drawn, for the first time, between the reactions of Fe(CO)4 and haemoglobin.

Abstraction of chloride from [Fe(CO)4(PPh2Cl)] (1) in the presence of PPh3 leads to [Fe(CO)4(PPh2(PPh3))][AlCl4] (2), an iron complex of a phosphine-coordinated phosphenium ion. The PPh3 is readily displaced by ferrocene, leading to an electrophilic aromatic substitution reaction, and formation of [Fe(CO)4{PPh2Fc}] (3) (Fc = ferrocenyl). Alternately, chloride abstraction from 1 in the presence of ferrocene leads directly to 3, via a transient phosphenium ion complex. The transient phosphenium ion complex also reacts with N,N-diethylaniline, indole, and pyrrole to form the respective p-anilinyl, 3-indolyl, and 2-pyrryl phosphine complexes via electrophilic aromatic substitution. Chloride abstraction from [Fe(CO)4(PPhCl2)] in the presence of ferrocene leads to a double substitution reaction, forming [Fe(CO)4{PPhFc2}] (13).

Instead of the expected carbon-carbon coupling into oxalates, thermolysis at 30 °C of the cis-bis(alkoxycarbonyl) monomers (CO)4Fe(CO2R)2 (1) affords the novel trimetallic compounds [(CO)3Fe(μ,η2-CO2R)3]2 Fe (R = Me (2a), t-Bu (2b), allyl (2c), 1,1′-dimethylallyl (2d)). As shown by 1H and 13C NMR, these complexes 2, which can be described as a central Fe(II) surrounded by two [(CO)3Fe(CO2R)3]- ligands, are paramagnetic. A Mo?ssbauer study of 2a and 2d revealed that these complexes display a high-spin configuration of their central iron atom and a low-spin configuration of the two lateral iron atoms. The easy formation of these complexes 2 by reacting fac-[(CO)3Fe(CO2R)3]- anions with FeCl2 suggests that formation of 2 by thermal evolution of 1 could occur via an associative mechanism, giving rise to the [(CO)3Fe(CO2R)3] pattern. Further thermolysis of 2 at 50 °C affords alcohols, Fe(CO)5, carbon monoxide, and bis(alkyl carbonates).

Fe3Te2(CO)9 is shown to be a useful precursor to a variety of heterometallic carbonyl clusters in reactions which appear to proceed via the intermediacy of Fe2(Te2)(CO)6.Fe3Te2(CO)9 decomposed in polar solvents to give Fe2(Te2)(CO)6 which could be dimerized to Fe4Te4(CO)12.Fe3Te2(CO)9 reacted with C5H5Co(CO)2 and Pt(C2H4)(PPh3)2 to give good yields of (C5H5Co)Fe2Te2(CO)7 and Fe2PtTe2(CO)6(PPh3)2, respectively. (C5H5Co)Fe2Te2(CO)7 underwent reversible decarbonylation to give a mixture of two isomers of (C5H5Co)Fe2Te2(CO)6 as established by 125Te NMR spectroscopy.Upon reaction with Co2(CO)8, Fe3Te2(CO)9 gave Co2FeTe(CO)9 or Co4Te2(CO)11 depending on the reaction conditions.Co4Te2(CO)11, like Fe3Te2(CO)10 and (C5H5Co)Fe2Te2(CO)7, can be reversibly decarbonylated.The assembly of Co2FeTe(CO)9 may be mechanistically related to the conversion of Fe2(S2)(CO)6 to FeCo2S(CO)9 which was found to proceed via Co2Fe2S2(CO)11.Alternatively, Co2Fe2S2(CO)11 reacted photochemically with 2 to give the known, chiral cluster (C5H5Mo)CoFeS(CO)8.While Fe2(Te2)(CO)6 thermally dimerized to Fe4Te4(CO)12, Fe2(S2)(CO)6 gave the analogous dimer only upon photolysis.In contrast to the stability of (C5H5Co)Fe2Te2(CO)7, the reaction of C5H5Co(CO)2 with Fe2(S2)(CO)6 gave only (C5H5Co)Fe2S2(CO)6 which is proposed to be structurally related to Fe3S2(CO)9 and not (C5H5Co)3S2 or Fe2PtS2(CO)6(PPh3)2.

LGeOH (1; L = HC[(CMe)(NAr)]2, Ar = 2,6-iPr2C 6H3) reacted with iron and manganese complexes to give LGe(OH)Fe(CO)4 (2) and LGe(OH)Mn(Cp)(CO)2 (3; Cp = cyclopentadienyl). Compounds 2 and 3

Evidence strongly suggests that the reaction Fe(CO)12 with CO yield Fe(CO)5 occurs via an electron transfer catalysed pathway; a mechanism for the reaction is proposed.

The new complexes cis- (R=Me or Et) and cis- (R,R'=Me, Et or i-Pr) have been synthesized.The bis-(alkyloxalyl) complexes decarbonylate at +12 deg C to their alkoxycarbonyl alkyloxalyl homologues.The latter decompo

The reaction of (HMe2Si)2NH with Co2(CO)8 gives the complex [Co2(CO)7(SiMe2)2NH 2]+[Co(CO)4]-. Its thermal decomposition starts with dissociation into the acid HCo(CO)4 and the base Co2(CO)7(SiMe2)2NH. After that, the base and the initial complex decompose further under the action of HCo(CO)4. The final products of this reaction are CO, NH3, Co, volatile dimethylcyclosilazane, and a solid residue consisting of cobalt particles encapsulated into a polymethylsiloxane matrix and possessing properties of mixed para-and ferromagnetics with an ultimate specific magnetization of 64-74 G g-1. Tetramethyldisilazane reacts with iron pentacarbonyl under UV irradiation to give relatively stable 1,3-bis(tetracarbonylhydrideiron)-1,1,3,3-tetramethyldisilazane. This product contains Fe - H...N hydrogen bonds, which stabilize it against dehydrogenation and cyclization to diironcyclodisilazane. Thermal decomposition of this product was investigated.

The photochemistry of Fe(CO)5 (5) has been studied in heptane, supercritical (sc) Ar, scXe, and scCH4 using time-resolved infrared spectroscopy (TRIR). 3Fe(CO)4 (34) and Fe(CO)3(solvent) (3) are formed as primary photoproducts within the first few picoseconds. Complex 3 is formed via a single-photon process. In heptane, scCH4, and scXe, 34 decays to form 14·L (L = heptane, CH4, or Xe) as well as reacting with 5 to form Fe2(CO)9. In heptane, 3 reacts with CO to form 14·L. The conversion of 34 to 14·L has been monitored directly for the first time (L = heptane, kobs = 7.8(±0.3) x 107 s-1; scCH4, 5(±1) x 106 s-1; scXe, 2.1(±O.1) x 107 s-1). In scAr, 34 and 3 react with CO to form 5 and 34, respectively. We have determined the rate constant (kCO = 1.2 x 107 dm3 mol -1 s-1) for the reaction of 34 with CO in scAr, and this is very similar to the value obtained previously in the gas phase. Doping the scAr with either Xe or CH4 resulted in 34 reacting with Xe or CH4 to form 14·Xe or 14·CH4. The relative yield, [34]:[3] decreases in the order heptane > scXe > scCH4 ? scAr, and pressure-dependent measurements in scAr and scCH4 indicate an influence of the solvent density on this ratio.

A bisphosphide-bridged diiron hexacarbonyl complex 3 with NEt2 groups on the phosphide bridge was synthesized to examine a new proton relay system from the NEt2 group to the bridging hydride between the two iron centers. As a precurs

Bis(trifluoromethyl)cadmium complexes Cd(CF3)2*L (L=2CH3CN or CH3OCH2CH2OCH3) react as perfluoroalkyl Grignard reagents with carbonyl-iron halides in a one-pot reaction to yield Fe-CF3 compounds easily.A strong solvent influence is observed.The dependence of the direction of the reactions, either as a trifluoromethylation or a fluorination, is discussed.In the presence of CH3CN a ligand-exchange reaction is observed, yielding trifluoromethyl iron acetonitrile complexes, while carbonyl complexes are obtained in ethers.The compound has been prepared in 65percent yield, and its (19)F n.m.r., i.r., Raman, mass, and Moessbauer spectra recorded.The adventage of observing the (13)C satellites in the (19)F n.m.r. spectra for the analysis of trifluoromethyl metal compounds is established.If the appropriate reaction conditions are used, Cd(CF3)2 complexes react as fluorination reagents and CF2 sources.Thus, on reaction of the trifluoromethyl cadmium reagents with tetracarbonyliron halides in CH3CN, diamagnetic fluoroiron acetonitrile complexes are formed.

The four-membered gallium(I) and. indium(I) heterocycles, [:M(Giso)] (M = Ga or In; Giso = [[N(Ar)I2CN(C6Hu)2)-, Ar = C6H3iPr2-2,6), were treated with a series of transition metal carbonyl

Addition of the electrophiles (CH3)+, H+, + to the metalladiborane anions 2-B2H5)>- (M = Fe, Ru, Os) has been investigated.Addition occurs at the metal center.The complexes CH3Os(CO)4(η2-B2H5), HM(CO)4(η2-B2H5) (M = Ru, Os) and (PPh3)AuM(CO)4(η2-B2H5) (M = Fe, Ru, Os) have been formed.NMR spectra of HM(CO)4(η2-B2H5) indicate that the H atom on the metal is cis to the B2H5 ligand.Relative stabilities of the complexes LM(CO)4(η2-B2H5) are in the order M = Os > Ru > Fe for a given electrophile and the order L = (Ph3P)Au > H for a given metal.

The first reduction steps of iron (II) in 2-propanol have been studied by pulse radiolysis technique. The rate constant value of the reaction of solvated electron with iron (II) was found to be 4.8 × 109 dm3 mol-1 s-1. The absorption spectrum of Fe(I) with a maximum at 350 nm was determined. The radiolytic reduction of FeII in 2-propanol under an inert atmosphere leads to the formation of very small iron nanoparticles whereas under a CO atmosphere, the stable Fe(CO)5 complex is formed.

The cis-dialkylcarboxytetracarbonyliron complexes were readily obtained from reaction of oxalyl chloride with the corresponding tetracarbonylcarboxyiron anion - (R = Me, 1a; R = Et, 1b). 1a underwent a clean ligand exchange with triphenylphosphine to give (2).Neither 1a nor 2 yielded dimethyl oxalate after thermolysis; rather, a mixture of methanol and methyl carbonate was obtained.The mobility of the alkoxy groups on 1 was shown by several exchange experiments.A clean reaction of the tetrafluoroboric acid ether with 1a gave + which was isolated and characterized by IR, 1H, and 13C NMR spectroscopy.

This paper presents a new method for investigating the mechanisms of homogeneously catalyzed reactions involving gases, particularly H2. We show how the combination of polyethylene (PE) matrices and high pressure - low temperature (HPLT) experiments can be used to provide new mechanistic information on hydrogenation processes. In particular, we show how we are able to generate reaction intermediates at low temperature, and then to extract the contents of the PE film at room temperature to characterize the organic products using GC-MS. We have used our new technique to probe both the hydrogenation of dimethyl fumarate (DF), using Fe(CO)4(η2-DF) as the catalytic species, and the hydrogenation of norbornadiene (NBD), using (NBD)M(CO)4 (M = Cr or Mo) as the catalytic species. Irradiation of Fe(CO)4(η2-DF) in a PE matrix at 150 K resulted in the formation of an intermediate complex tentatively assigned Fe(CO)3(η4-DF). Warming this complex to 260 K under H2 leads to the formation of Fe(CO)3(η2-DF)(η2-H2). Further warming of the reaction system results in the hydrogenation of the coordinated DF, to generate dimethyl succinate (DS). Characterization of the intermediate species was obtained using FTIR spectroscopy. Formation of DS was confirmed using both FTIR spectroscopy and GC-MS analysis. UV photolysis of (NBD)M(CO)4 in PE under H2 in the presence of excess NBD results in the formation of the hydrogenated products norbornene (NBN) and nortricyclene (NTC), with trace amounts of norbornane (NBA) being observed. These products were in similar ratios to those observed in fluid solution. However, for (NBD)Mo(CO)4, the relative amounts of the organic products change considerably when the reaction is repeated in PE under H2 in the absence of free NBD, with NBA being the major product. The use of our HPLT cell allows us to vent and exchange high pressures of gases with ease, and as such we have performed gas exchange reactions with H2 and D2. Analysis of the reaction products from these exchange reactions with GC-MS provides evidence for the mechanism of formation of NBA, in both the presence and absence of excess NBD, a reaction which has been largely ignored in previous studies.

The reaction of Fe(CO)5 with base to form HFe(CO)4- has a rate-determining step Fe(CO)5 + OH- -> Fe(CO)4COOH- (k1) at high base concentration with k1 = 70 M-1 s -1 at 25 deg C in 70:30 methanol-water.At low base concentration the rate-determining step is Fe(CO)4CO22- -> Fe(CO)42- + CO2 (k3), with the observed rate depending on the square of the total base concentration.The thermal decomposition of H2Fe(CO)4 has a rate-determining step of H2Fe(CO)4 -> H2 + Fe(CO)4 and a stoichiometry in 70:30 methanol-water of 4H2Fe(CO)4 -> 3H2(*) + H2Fe3(CO)11 + Fe(CO)5.In the water-gas shift reaction, Fe(CO)5 is a poor catalyst because of the conficting pH requirements of the two cyclic processes.

Kinetic studies of selected metal carbonyl anions establish their reactivity as nucleophiles or for electron transfer. The iron species, [HFe(CO)3L]- (L = CO, PPh3), behave as metal-centered nucleophiles when reacted with [M(CO)6]+ (M = Mn, Re). Determination of the deuterium kinetic isotope ratio from kinetic studies of [HFe(CO)4]- and [DFe(CO)4]-, kH/kD = 2.8, indicates primary isotope effects for reaction with Mn(CO)6+. Initial products from transfer of a CO and back transfer of two electrons are observed in some cases. For Re-(CO)6+ exclusive formation of HRe(CO)5 as a rhenium product strongly indicates a hydrogen transfer mechanism.

Reaction of [Fe(CO)4(η2-BTMSA)] (1) (BTMSA = Me3SiCCSiMe3) with trimethylphosphine proceeds by stepwise loss of CO ligands yielding [Fe(CO)3(PMe3) (η2-BTMSA)] (2) and [Fe(CO)sub

The reaction of carbanions with the pyruvoyl-substituted iron complex [(CO)4Fe(CO2CH3){C(O)C(O)CH3}] (1) affords the anionic trifunctionalized metallalactones [(CO)3Fe{C(O) C(CH3)(CRR′R″)OC4(O)(Fe-C4)} (CO2CH3)]- (3), whose formation results from the addition of the nucleophile to the β carbonyl of the pyruvoyl moiety, followed by attack of the oxygen of this β carbonyl on a terminal carbonyl ligand. These anionic lactones react, at low temperature, with HCl to give rise to the neutral lactones [(CO)4Fe{C(O)C(CH3) (CRR′R″)OC4(O)(Fe-C4)}] (2), which were previously obtained by addition of NuH nucleophiles to 1. Complex 3(3), whose lactonic ring formation has been performed using the diethyl malonate anion (R = R′ = CO2C2H5; R″ = H), and the dimethyl-substituted neutral lactone 2(1) (R = R′ = R″ = H) have been characterized by X-ray diffraction studies. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Treatment of Fe(OAc)2 in THF with 2 equiv of Li(CPh3) at -25 °C results in the formation of [Fe(ν5-CPh3)2] (1) in 22% yield. Complex 1 was characterized by X-ray crystallography, NMR spectroscopy, and 57Fe M?ssbauer spectroscopy and features an ν5 binding

Earth abundant, first row transition metals offer a cheap and sustainable alternative to the rare and precious metals. However, utilization of first row metals in catalysis requires harsh reaction conditions, suffers from limited activity, and fails to tolerate functional groups. Reported here is a highly efficient iron catalyzed hydroformylation of alkenes under mild conditions. This protocol operates at 10-30 bar syngas pressure below 100 °C, utilizes readily available ligands, and applies to an array of olefins. Thus, the iron precursor [HFe(CO)4]-[Ph3PNPPh3]+ (1) in the presence of triphenyl phosphine catalyzes the hydroformylation of 1-hexene (S2), 1-octene (S1), 1-decene (S3), 1-dodecene (S4), 1-octadecene (S5), trimethoxy(vinyl)silane (S6), trimethyl(vinyl)silane (S7), cardanol (S8), 2,3-dihydrofuran (S9), allyl malonic acid (S10), styrene (S11), 4-methylstyrene (S12), 4-iBu-styrene (S13), 4-tBu-styrene (S14), 4-methoxy styrene (S15), 4-acetoxy styrene (S16), 4-bromo styrene (S17), 4-chloro styrene (S18), 4-vinylbenzonitrile (S19), 4-vinylbenzoic acid (S20), and allyl benzene (S21) to corresponding aldehydes in good to excellent yields. Both electron donating and electron withdrawing substituents could be tolerated and excellent conversions were obtained for S11-S20. Remarkably, the addition of 1 mol % acetic acid promotes the reaction to completion within 16-24 h. Detailed mechanistic investigations revealed in situ formation of an iron-dihydride complex [H2Fe(CO)2(PPh3)2] (A) as an active catalytic species. This finding was further supported by cyclic voltammetry investigations and intermediacy of an Fe(0)-Fe(II) species was established. Combined experimental and computational investigations support the existence of an iron-dihydride as the catalyst resting state, which then follows a Fe(II) based catalytic cycle to produce aldehyde.

The [NiFe]-hydrogenase model complex NiFe(pdt)(dppe)(CO)3 (1) (pdt = 1,3-propanedithiolate) has been efficiently synthesized and found to be robust. This neutral complex sustains protonation to give the first nickel-iron hydride [1H]BF4. One CO ligand in [1H]BF4 is readily substituted by organophosphorus ligands to afford the substituted derivatives [HNiFe(pdt)(dppe)(PR3)(CO)2]BF4, where PR 3 = P(OPh)3 ([2H]BF4); PPh3 ([3H]BF4); PPh2Py ([4H]BF4, where Py = 2-pyridyl). Variable temperature NMR measurements show that the neutral and protonated derivatives are dynamic on the NMR time scale, which partially symmetrizes the phosphine complex. The proposed stereodynamics involve twisting of the Ni(dppe) center, not rotation at the Fe(CO)2(PR3) center. In MeCN solution, 3, which can be prepared by deprotonation of [3H]BF4 with NaOMe, is about 104 stronger base than is 1. X-ray crystallographic analysis of [3H]BF4 revealed a highly unsymmetrical bridging hydride, the Fe-H bond being 0.40 A shorter than the Ni-H distance. Complexes [2H]BF4, [3H]BF4, and [4H]BF4 undergo reductions near -1.46 V vs Fc0/+. For [2H]BF4, this reduction process is reversible, and we assign it as a one-electron process. In the presence of trifluoroacetic acid, proton reduction catalysis coincides with this reductive event. The dependence of i c/ip on the concentration of the acid indicates that H2 evolution entails protonation of a reduced hydride. For [2H] +, [3H]+, and [4H]+, the acid-independent rate constants are 50-75 s-1. For [2H]+ and [3H]+, the overpotentials for H2 evolution are estimated to be 430 mV, whereas the overpotential for the N-protonated pyridinium complex [4H 2]2+ is estimated to be 260 mV. The mechanism of H 2 evolution is proposed to follow an ECEC sequence, where E and C correspond to one-electron reductions and protonations, respectively. On the basis of their values for its pKa and redox potentials, the room temperature values of ΔGH? and ΔGH- are estimated as respectively as 57 and 79 kcal/mol for [1H]+.

Iron azadithiolate phosphine-substituted complex and its protonated species featuring the NH proton and/or bridging Fe hydride, [Fe2(μ- S(CH2)2NnPr(H)m(CH2) 2S)(M-H)n(

The thioester Ph2PC6H4-2-C (O ) SPh reacts with Fe2(CO)9 to give [Ph2PC6H 4C(O)]Fe(SPh) (CO)3, a model for the CO-inhibited active site of the enzyme Hmd. T

Thermal evolution at 4 °C of the structurally characterized cis(CO)4Fe[C(O)C(O)CH3][C(O)CH3] (1(2)) gives rise to the cis(CO)4Fe[C(O)CH3]2 (1(3)) which, probably owing to synthetic problems, has never been described in the literature. By reaction with anionic nucleophiles (Nu-), 1(2) affords anionic trifunctionalized metallalactones {(CO)3Fe[C(O)CH3][C(O)C(CH3)(Nu)OC 7(O);(Fe-C7)]}- (3) formed by addition of the nucleophile reagent on the β carbon of the pyruvoyl moiety followed by the cyclization of this ligand on a terminal carbonyl of the complex. Anions 3 are characterized by 1H and 13C NMR and by X-ray diffraction for the complex with Nu = C(H)(CO2C2H5)2. Complexes 3 are also prepared by reaction of CH3Li with the neutral metallalactones (CO)4Fe[C(O)C(CH3)(Nu)OC7(O); Fe-7C] (2). The results of this study shed light on the reaction of cyclization of a pyruvoyl ligand as they clearly show that the presence of a second ligand (for example CO2R) with a labile OR group is not required to perform the formation of the metallalactone ring and then that the observed reaction has no connection with organic chain-ring transformations.

Anionic nucleophilic reagents Nu- = CH3O-, C2H5O-, t-BuO-, CH 3S-, and P(C6H5)2 - were found to react with (CO)

The synthesis and characterisation of complexes of two distibinopropanes R2Sb(CH2)3SbR2 (R = Me or Ph) with a variety of metal carbonyls is described. These include cis-[M(CO) 4{R2Sb(CH2)3SbR2}] (M = Cr, Mo or W), [{Fe(CO)4}2{μ-R2Sb(CH 2)3SbR2}], [{Ni(CO)3} 2{μ-R2Sb(CH2)3SbR2}], [Co2(CO)6{Ph2Sb(CH2) 3SbPh2}], [Co2(CO)4{Me 2Sb(CH2)3SbMe2}3][Co(CO) 4]2 and [Mn2(CO)8{Ph 2Sb(CH2)3SbPh2}]. The complexes have been characterised by analysis, mass spectrometry, IR and multinuclear NMR spectroscopy as appropriate. Comparison of the spectroscopic data on these complexes with those of other stibine complexes and with complexes of Group 16 ligands has been used to establish the relative electronic properties of the distibines.

A family of low-valent α-diimine iron complexes has been synthesized and their utility in catalytic olefin hydrogenation reactions evaluated. Reduction of the ferrous dichloride complex [ArN=C(Me)C(Me)=NAr]FeCl2 (Ar = 2,6-(CHMe2)2-C6H3) with sodium amalgam in benzene or toluene furnished the iron arene complexes, [ArN=C(Me)C(Me)=NAr]Fe(η6-C6H5R) (R = H, Me). The solid-state structure of the toluene adduct revealed a contracted carbon-carbon backbone, short iron-imine bonds, and elongated imine nitrogen-carbon distances, suggesting significant reduction of the α-diimine ligand. The analogous reduction in alkane solvents afforded the bis(α-diimine) complex [ArN=C(Me)C(Me)=NAr]2Fe, which has also been crystallographically characterized. The arene complexes and the bis(a-diimine) complexes are inactive for catalytic olefin hydrogenation. Performing the reduction in the presence of internal alkynes such as diphenylacetylene and bis(trimethylsilyl)acetylene furnished the alkyne adducts [ArN=C(Me)C(Me)=NAr]Fe(η2-RC=CR) (R = Ph, SiMe3 ). Analogous olefin complexes with 1,5-cyclooctadiene and cycloctene have also been isolated using similar reduction procedures. The olefin adducts provide more active precatalysts than the alkyne compounds for the hydrogenation of 1-hexene. In each case, formation of rfarene adducts serves as a major catalyst deactivation pathway.

The reaction of MesC≡P (Mes = 2,4,6-Me3C6H 2) with [(Ph3P)2Pt(η2-C 2H4)] leads to [(Ph3P)2Pt(η 2-PCMes)] (1) whereas with Fe2/su

Reaction of primary carbamoyl ferrates {(CO)4Fe[C(O)NHR]} - (R=Me, Et, allyl, decyl, cyclohexyl, t-butyl, benzyl, phenyl) with 1/2 equiv. of oxalylchloride affords cis-bis-carbamoyl intermediates: (CO) 4Fe[C(O)NHR]2 which thermally give rise, in good yields, to the mono-isocyanide complexes (CO)4Fe(CNR). The mechanism of the reaction is discussed. Via a similar process, an alkoxycarbamoyl intermediate (CO)4Fe[C(O)NHR](CO2Me) affords Fe(CO)5 and 1,3-dialkylurea.

The new iron carbonyl cyanide trans-[Fe(CN)2(CO) 3]2-, [2]2-, forms in high yield via photosubstitution of Fe(CO)5 with 2 equiv of Et4NCN. Protonation of [2]2- generated [HFe(CN)

The reaction of oxalyl chloride with various tetracarbonyl ferrates bearing a carbonylated organic ligand induces the formation of bis substituted monomers Fe[C(O)R]2(CO)4 or dimers (Fe[C(O)R](CO)4)2 and of bis-[μ,η2-C(O)R]Fe2(CO)6 bridged dimers. The orientation of the reaction depends on the nature of the organic ligand of the ferrates. Thus carbamoyls or alkoxycarbonyls ferrates bearing mobile R groups are found to induce the formation of bis substituted monomers while bulky alkoxycarbonyl ligands afford non-bridged dimers. Acyls and bulky carbamoyls give rise to dimers bearing bridging acyls or carbamoyls. The mechanisms of formation of these different complexes and the possible thermal interconversions of these compounds are investigated.

Fe(CO)5 reacts with [PPh2]- in THF at -78 °C to give the adduct [(CO)4FeCOPPh2]- (3) which decomposes at elevated temperature to give [(CO)4FePPh2]- (1), [Fe2(CO)8]2- (2) and (Ph2P)2 probably via a radical mechanism. Attempts to transfer 3 with the electrophiles MeSO3CF3 or Me3SnCl into the corresponding carbenes have failed and Fe(CO)5 along with Ph2PMe and Me3SnPPh2, respectively, are formed. 1 adds one equivalent of CS2 to generate [(CO)4FePPh2CS2]- (4). The [K-18-Krone-6] salt of 1 crystallizes in the triclinic space group P 1 with the unit cell parameters a = 929.5(2), b =1112.1 (2), c - 2017.9(4) pm, α = 100.29(3)°; β = 94.07(3)°; γ = 114.58(3)°. The existence of 3 is established by low temperature 31P NMR spectroscopy.

The 1,3-dipolar cycloaddition reaction of Fe[R*-DAB(H;H)](CO)3 (6k; R*-DAB(H;H) = R*-N=C(H)-C(H)=N-R*) with dimethyl acetylenedicarboxylate (DMAD), in which the R*-DAB(H;H) ligand is C2-symmetric and is chirally N-substituted, gives the two expected diastereomers with low diastereoselectivity, due to a small difference in the rate constants of the two reactive C=N groups in 6k exposing their re and si faces, respectively. The 1,3-dipolar cycloaddition reaction of Fe(α-diimine)(CO)3 (1, 6m) with DMAD and methyl propiolate (MP), in which a non-C2-symmetric α-diimine ligand (R*-DAB(H;Me) and Py-2-C(R′)=N-R* (R*,R′-PyCa) is chirally N-substituted, gives the two expected diastereomers with medium to high diastereoselectivity. The diastereoselectivity with the non-C2-symmetric α-diimine ligands, which have only one reactive imino group, depends on the size of the chiral group R*, the distance of the chiral group to the reacting centers, and the type of dipolarophile. The two starting complexes (1 and 6m) exist in solution in the form of two - rapidly interconverting diastereomeric conformers I and II. In contrast to the C2-symmetric case, the free energies of activation for the two different conformers and their respective concentrations may be quite different here. The diastereoselectivities could not be influenced by variation of temperature, solvent, or the additional ligand. Kinetic resolution by a cycloreversion reaction could be excluded by the use of a chiral additional ligand and an achiral α-diimine ligand (i-Pr, H-PyCa, or i-Pr-DAB(H; H)). X-ray crystal structures have been determined from the respective diastereomeric mixtures of the pyrrolinone complex 5cks and the [2.2.2] bicyclic product 7aks. The structures of the [2.2.2] bicyclic product 4aks and of the free pyrrolinone ligand 8als have been determined using diastereomerically pure products. The 5-(2-pyridyl)pyrrolin-2-one ligands 8 are decomplexed from their precursors 5 by Me3NO, air oxidation, exchange by CO, and oxidative reactions with dihalogens or H2O2.

Ferra-γ-ketoesters 1 and 2 induce thermally either a carbon-carbon coupling process or a chain-ring isomerization; the orientation of the reaction likely depends on the proximity of the ester group to the metal centre.

The dinuclear carbonylmetalate [Fe2(CO)8]2- forms deeply colored crystals A2[Fe2(CO)8] with various phosphonium and pyridinium cations (A+) by metathesis in aqueous solution. Diffuse reflectance absorption spectroscopy and X-ray crystallography establish the colors to derive from anion-to-cation charge-transfer (CT) within the triple ion [A+, Fe2(CO)82-, A+] extant in the solid state. Partial electron transfer in the charge-transfer salts is established by the significant shortening of the iron-iron bond in the [Fe2(CO)8]2- moiety when it is ion paired with the N-methyllutidinium acceptor. In solution, the charge-transfer salts can undergo interionic electron transfer, and they lead to the dimeric A2 and a series of iron carbonyl products that are uniquely dependent on the solvent (water, ether, and acetonitrile).

The halides Cl-, Br-, and I- and the pseudo-halide NCO- react with Fe3(CO)12 (1) in aprotic solvents to induce a disproportionation reaction yielding the radical anion [Fe3(CO)s

Addition of triphenylphosphine to the cluster (1-) yielded the derivative (1-), which is stable enough to allow a single-crystal X-ray analysis on the (1+) salt.The cluster contains a triangular metallic framework, the vertices of which are occupied by two Fe(CO)4 groups and one Rh(CO)(PPh3) moiety; the unsaturation of the cluster (46 valence electrons) is brought about by this 16-electron square-planar fragment.The cluster (2-) was obtained by treating with (1-) (molar ratio 1 : 2) in refluxing acetone, and was characterized by infrared spectroscopy and elemental analyses.The adduct >(1-) was prepared by stoichiometric addition of in acetone and the crystal structure of the (1+) salt was elucidated by X-ray analysis.The cluster contains a trigonal-bipyramidal arrangement of metal atoms, with one Au(PPh3) and one Fe(CO)3 group occupying the apical positions.The vertices of the FeRh2 equatorial plane are bound to two terminal carbonyl ligands, and the edges are spanned by three bridging carbonyls.The 31P NMR spectral data for (1-) and >(1-) are consistent with the solid-state structures, but do not exclude the presence of fluxional processes in solution.

The energetics and mechanism of decarboxylation of (CO)4FeCOOH- to form CO2 and (CO)4FeH-, a key step in the Fe(CO)5-catalyzed water-gas shift reaction, is investigated using the flowing afterglow-triple quadrupole technique. Previous studies of collisional activation of (CO)vFeCOOH- in the gas phase showed only loss of CO ligands, suggesting that base catalysis is necessary for decarboxylation. We have now observed gas-phase decarboxylation of this hydroxycarbonyl km using energy-resolved collision-induced dissociation. Decarboxylation competes with decarbonylation at translational energies near the reaction threshold, indicating that unimolecular β-elimination of CO2 can occur. Loss of two carbonyl ligands to form (CO)3FeOH- is the dominant process at somewhat higher energies. The thresholds for loss of CO, 2CO, and CO2 are 21.4 ± 3.9, 30.2 ± 2.8, and 18.9 ± 3.2 kcal/mol, respectively. The latter number corresponds to a barrier for an exothermic reaction. DH[Fe(CO)5-OH-] = 60.8 ± 3.4 kcal/mol is determined by measurement of the equilibrium constant for hydroxide exchange between Fe(CO)5 and SO2. (CO)4FeSOOH- + CO2 is formed as a side product of this reaction, and the structure of this species is investigated. These data are combined with other thermochemistry to derive a model reaction-energy profile for the Fe(CO)5-catalyzed water-gas shift reaction.

In the photochemically induced reaction of Ru2(CO)6{RC=C(H)CH2N-iPr} (1a, R = Ph; 1b, R = Me) with Fe2(CO)9 the heteronuclear complex HFeRu(CO)5{RC=C(H)C(H)=N-iPr} (5) is formed in 35 % yield. HRu2(CO)6{RC=C(H)C(H)=N-iPr} (4), which is prepared quantitatively by photolysis of H2Ru4(CO)8{RC=C(H)C(H)=N-iPr}2 under a CO atmosphere, can act as an intermediate in this reaction and is proposed to be formed from 1 by a β-H-elimination reaction. Complex 5 is most likely formed via oxidative addition of the Ru-H bond in 4 to a Fe(CO)4 fragment. Complex 5 reacts with CO at 293 K to give reductive elimination of the monoazadiene ligand and formation of Fe(CO)5/Ru3(CO)12, probably via a mechanism involving opening of the hydride bridge. In the reaction of 5 with CO at 373 K the hydride is shifted to the monoazadienyl (MAD-yl) ligand, which is reduced from formally monoanionic to dianionic. In the case of R = Ph selective hydride transfer to Cβ is observed, resulting in the formation of FeRu(CO)6-{PhC(H)C(H)C(H)N-iPr} (6a), which features an unprecedented coordination mode of the MAD-yl ligand. For R = Me, both transfer to Cβ (affording 6b) and to Cim is observed, the latter affording FeRu(CO)6{MeC=C(H)CH2N-iPr} (7). This R-group dependence and also the difference in the reactivity of 5 and its homonuclear Ru2 analogue 2 is rationalized by the strength of the π-C=C coordination in the intermediate HFeRu(CO)6{RC=C(H)C(H)=N-iPr} (9). Complex 9a could not be prepared by the reaction of [FeRu(CO)6(PhC=C(H)C(H)=N-iPr}][BF4] (8a) with NaBH4, which afforded one diastereomer of FeRu(CO)6{PhCC(H)C(H)N-(H)-iPr} (10a), but 9a was formed by the conversion of 8a on silica. The X-ray crystal structures of 6a and 9a have been determined. Crystals of 6a are monoclinic, space group P21/c, with unit-cell dimensions a = 12.106(14) A?, b = 9.490(10) A?, c = 16.780(7) A?, β = 97.61(7)°, V = 1911(3) A?3, Z = 4, final R = 0.055, and Rw = 0.040 for 2215 reflections with I > 3.0σ(7) and 245 parameters. Crystals of 9a are orthorhombic, space group P212121, with a = 9.819(1) A?, b = 11.928(1) A?, c = 17.338(1) A?, V = 2030.7(3) A?3, Z = 4, and final R = 0.044 for 1434 reflections with I > 2.5σ(7) and 254 parameters. The most important conclusion of this work is that isostructural FeRu- and Ru2-MAD-yl complexes show a large difference in reactivity, which can be rationalized by stronger π-coordination of the MAD-yl ligand to Fe as compared to Ru.

The chemistry of B6H10Fe(CO)4 (I) and its conjugate base [B6H9Fe(CO)4]- (II) has been extended. 11B and 1H NMR spectra and the crystal and molecular structure of I are reported. I crystallizes in the orthorhombic space group Pbca, with a = 11.441(3) ?, b = 11.696(4) ?, c = 16.396(3) ?, and Z = 8. The crystal structure determination of this air-sensitive species indicates that the cage geometry is not substantially different from that of the parent borane. The position of the Fe atom is well below the basal B5 plane, the dihedral angle being 55.7°. The angles around the Fe atom suggest trigonal-bipyramidal geometry with the axial Fe-C bond diverging from linearity by ca. 6°. I is readily deprotonated with KH to afford the conjugate base [B6H9Fe(CO)4]- (II). Variable-temperature NMR spectra for II indicate complex dynamic processes, and the data are interpreted in terms of fluxional motion of the bridging H atoms, which is quenched at ca. -130°C, and also of the borane cage relative to the Fe(CO)4 moiety, which is quenched at ca. -10°C. Two processes are identifed for the former: complete scrambling of the three bridging H atoms among the four available sites above -50°C and a process that is partially quenched in which only one H atom moves above -100°C.

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4-SiMe)2(CO)11> (1a) is the major product from the reaction of with (synthesised from SiMeH2Cl and Na2).An alternative, quantitative synthesis of 1a is from SiMeH3 and , 1a reacts with an

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Reactions of Fe(CO)42- with metal carbonyl complexes lead to distinct mechanisms. Reaction with metal carbonyl cations gives a two-electron process that we interpret as a CO2+ transfer. Reaction with Mn2(CO)10 occurs by a single-electron transfer producing Fe2(CO)82- and Mn(CO)5-. Reaction with Mn(CO)5Br also occurs by a single-electron transfer. Reaction with Re(CO)5Br could be either SET or direct nucleophilic displacement. Kinetic studies are reported for several reactions.

The reactions of species produced on gas-phase excimer laser photolysis of Fe(CO)5 have been followed by transient infrared spectroscopy employing a diode laser probe.The initial photoproducts formed on 193-nm photolysis are identified as Fe(CO)2 and a product that is most likely Fe(CO).Both Fe(CO)2 and Fe(CO)3 are produced on 248-nm photolysis.Photolysis at 351 nm leads to the production of both Fe(CO)3 and Fe(CO)4.Species best assigned as excited states of Fe(CO)3 and Fe(CO)4 are observed to form as initial photoproducts following 248- and 351-nm photolysis, respectively.The magnitudes of the rate constants for reaction of the various coordinatively unsaturated metal carbonyls formed in this study with parent Fe(CO)5 or CO (summarized in Table I) are consistent with the hypothesis that spin-allowed reactions will be rapid while spin-disallowed reactions will be considerably slower.To provide further data in testing this hypothesis, the reaction of Fe(CO)4 with both O2 and H2 has been measured.

Full title: Electron transfer between mononuclear metal carbonyl anions (M(CO)5-, M = Mn, Re; CpFe(CO)2-; CpM(CO)3-, M = Cr, Mo) and trinuclear clusters (M3(CO)12, M = Fe, Ru, Os) and between trinuclear dianions (M3(CO)112-, M = Fe, Ru, Os) and metal carbonyl dimers (Mn2(CO)10 and Cp2M2(CO)6, M = Cr, Mo, W). Reaction of mononuclear metal carbonyl anions with trinuclear clusters of group 8 (M3(CO)12, M = Fe, Ru, Os) at ambient conditions leads to four separate outcomes: (1) formation of the metal carbonyl dimer and the trinuclear dianion which occurs whenever the two-electron reduction potential for the dimer is more negative than for the trinuclear cluster, (2) formation of MFe2(CO)7- by elimination of Fe(CO)5 which occurs for M = Re(CO)5, Mn(CO)5, and CpMo(CO)3, (3) formation of the adduct, MRu3(CO)11-, which occurs for Re(CO)5, and (4) no reaction when the two-electron reduction potential for the trinuclear complex is more negative than for the dimer. For complexes where the two-electron potential for the cluster is more negative than for the dimer, reaction of M3′(CO)112- with M2 to give M3′(CO)12 and 2M- is observed. The observed reactions allow an estimate of the two-electron reduction potentials for the trinuclear clusters. The kinetics of all of these reactions indicate a first-order dependence on the oxidant and on the reductant and are most consistent with outer-sphere electron transfer.

The radiolytic reduction of metal ions in alcohols has been achieved under CO atmosphere.Under such conditions, metal reduction, ligation and aggregation processes compete, leading to metal complexes and molecular clusters.These products are interesting for catalytic purposes.We report here the radiolytic synthesis of compounds of Fe, Ru, Os, Co, Ir, Rh, Pt, Cu, Ag, and of some intermetallic compounds.These syntheses are carried out under very mild temperature and pressure conditions (i.e., room temperature and at most 1 atmosphere of CO).Factors favoring a high nuclearity are the concentration, the high atomic number, a weak ligand/metal ratio.It is shown that chloride ions are inhibitors of complete reduction.

Potassium tetracarbonylhydriodoferrate, KHFe(CO)4, reacts with aryl iodides in wet methanol to yield the corresponding arenes. This reaction is catalytic under carbon monoxide (1 atm) in the presence of an excess of base. Mechanistic investigations, both by IR analysis and by electrochemical experiments, show that the reaction involves an electron transfer from HFe(CO)4- to the aryl halide to generate the corresponding radical anion. The resulting aryl radical either abstracts an hydrogen atom from potassium methoxide of combines with the [HFe(CO)4] radical species to form ArFe(H)(CO)4, which yields ArH by reductive elimination. The catalytic carbonylation of iodobenzene to benzoic acid can be performed under very mild conditions by a bimetallic system, viz. HFe(CO)4--Co(CO)4-. The observed synergetic effect is believed to involve first an electron transfer from HFe(CO)4- to iodobenzene and generation of a phenyl radical, followed by reaction with Co(CO)4-, which acts as the actual carbonylation catalyst. In agreement with these hypotheses, the carbonylation of bromobenzene, which on its own is unreaction under these conditions, can be promoted by the presence of iodobenzene.

In an attempt to investigate the various reaction pathways available for C-C bond-forming reactions, the synthesis and study of the chemical behavior of the binuclear complex bis(μ,η2-decanoyl)hexacarbonyldiiron was undertaken. Thermal decomposition of the complex in cyclohexane yields three organic products, n-octadecane, 10-nonadecanone, and 10,11-eicosadione. The principal organometallic product is Fe(CO)5. The decomposition when monitored by FT-IR spectroscopy displays a clean first-order kinetics and is characterized by an unusually large negative entropy of activation, ΔS? = -29.7 eu (log A = 6.07). Absence of crossover products in the combined decomposition of mixtures of bis(acyl)diiron complexes indicates that the principal products are formed in processes that do not involve alkyl group scrambling and presumably occur by intramolecular pathways. Additional evidence for this postulate is derived from the observed kinetics of the reaction of the diiron complex with triphenylphosphine, implying a unimolecular rate-determining equilibrium step prior to a fast product-forming sequence. The reactivity of the bis(decanoyl)hexacarbonyldiiron complex with methyl iodide, methyl alcohol, and acetic acid is also briefly examined.

Aromatic aldehydes react with Fe3(CO)12 in refluxing benzene ultimately to give arylmethyl alcohols and 1,2-diaryl-1,2-ethanedione in a 1:1 ratio.In some cases, small amounts of 2,4,5-triaryl-1,3-dioxolanes are formed as minor products.Dinuclear iron complex (1,2-diphenyl-1,2-ethanedioxido)Fe2(CO)7 has been isolated as an intermediate in the reaction of benzaldehyde with Fe3(CO)12.The mechanism of this redox reaction of aromatic aldehydes are discussed on the basis of the kinetic study of the reaction and also of the reactivity of the isolated dinuclear iron complex.