Methyl Iron Complex Research Articles

Desulfurization of N,N-dimethylthioformamide by hydrosilane with the help of an iron complex. Isolation and characterization of an iron–carbene complex as an intermediate of CS double bond cleavage

Desulfurization of N,N-dimethylthioformamide (Me(2)NCHS) by hydrosilane has been achieved under photo irradiation in the presence of a methyl iron complex. The reaction sequences have been proposed, in which silyl migration from Fe to S of thioformamide triggers the cleavage of a C=S bond to give a carbene-iron complex. This intermediate was isolated and characterized by X-ray analysis.

Trans-selective hydrogermylation of alkynes promoted by methyliron and bis(germyl)hydridoiron complexes as a catalyst precursor

Catalytic trans-selective hydrogermylation of terminal and internal alkynes was attained by a methyliron complex, CpFe(CO)(2)(Me), and a bis(germyl)hydridoiron(IV) complex as a catalyst precursor. The structures of (Z)-triphenyl-(2-phenylethenyl)germane and the bis(germyl)hydridoiron(IV) complexes CpFe(CO)(H)(GeR(3))(2) (R = Et, Ph) were confirmed by single crystal X-ray diffraction studies.

Synthesis, Characterization, and Crystal Structure of Germyl(phosphine)iron Complexes, Cp(CO)Fe(PPh3)(GeR3) (R = Et, n Bu, Ph), Prepared from Cp(CO)Fe(PPh3)(Me) and HGeR3

Photoreaction of Cp(CO)2Fe(Me) (Cp stands for η5-cyclopentadienyl) with PPh3 afforded Cp(CO)Fe(PPh3)(Me). Reaction of the methyl iron complex with HGeR3 (R = Et, nBu, Ph) produced Cp(CO)Fe(PPh3)(GeR3) (R = Et: 1, nBu: 2, Ph: 3). All new complexes were fully characterized using 1H, 13C{1H}, and 31P{1H} NMR measurements and elemental analyses. Furthermore, the structure of 3 was determined using single crystal X-ray analysis.

8-(Diphenylphosphanyl)naphthyl-κ2C1,P](phenylethynyl)tris(trimethylphosphane-κP)iron(II)

The title compound, [Fe(C8H5)(C22H16P)(C3H9P)3], was synthesized by the addition of phenyl­ethine to a solution of the parent methyl iron complex Fe(CH3){P(C6H5)2(C10H6)}(PMe3)3 at 213 K, accompanied by evolution of methane. The coordination around the iron center can be described as slightly distorted octa­hedral [Fe—P 2.2485 (12)–2.2902 (12) Å; Fe—C 1.918 (5), 2.015 (4) Å], with a meridional arrangement of the trimethyl­phosphine ligands and the introduced terminal alkinyl-ligand trans to the P(Ph)2-anchoring group.

C–H activation of diphenylphosphinoaryl-derivatives with dimethyltetrakis(trimethylphosphine)iron(II)

Fe(CH 3) 2(PMe 3) 4 reacts with 1-(diphenylphosphino)naphthalene or benzyldiphenylphosphine within 4 h at 20 °C to give the novel metallated methyl iron complexes Fe(CH 3){P(C 6H 5) 2(C 10H 6)}(PMe 3) 3 ( 1) and Fe(CH 3){(C 6H 4)CH 2P(C 6H 5) 2}(PMe 3) 3 ( 3), respectively, via selective activation of the C–H bond of the pre-chelating ligands. The complexes are thermally unstable releasing metal through a reductive elimination of the aromatic backbone and leading to a C,C-coupling product that is regiospecifically methylated, namely 8-methyl(diphenylphosphino)naphthalene ( 2). Carbonylation (1 bar, 20 °C, 1 h) of complex 1 effects monosubstitution of a trimethylphosphine ligand trans to the metallated 8-C atom to afford Fe(CH 3){P(C 6H 5) 2(C 10H 6)}(CO)(PMe 3) 2 ( 4). The remaining methyl group in the parent complex 1 reacts with trimethylsilylethyne and tert-butylethyne affording the new complexes 5 and 6 bearing an alkynyl substituent trans to the diphenylphosphino anchoring group. The complexes 1 and 3– 6 are diamagnetic and possess octahedral coordination geometry. All novel complexes were fully characterized by spectroscopic methods and by X-ray diffraction.

The first example of a structurally characterized octahedral hydrotris(pyrazolyl)borate iron methyl complex

The one-step synthesis of the known acetyl complex κ 3-TpFe(CO)(PMe 3)(COMe) ( 1, 78% yield) is achieved by reaction of cis, trans-Fe(CO) 2(PMe 3) 2MeI with potassium hydrotris(pyrazolyl)borate (KTp), in CH 2Cl 2 at room temperature. This reaction is specific to the parent Tp ligand. Visible light irradiation of 1 in toluene for 1 h afforded the first octahedral methyl–iron complex featuring the hydrotris(pyrazolyl)borate ligand TpFe(CO)(PMe 3)Me ( 2) in 80% yield. Compound 2 has been fully characterized by elemental analysis, IR, NMR spectroscopies, cyclic voltammetry and by an X-ray diffraction analysis. A comparison of steric and electronic properties is made with those of related cyclopentadienyl (Cp, Cp*, C 5Ph 5) complexes, and suggests that relative donating abilities follow the trend Cp, Cp*, C 5Ph 5>Tp, and structural comparisons indicate that Tp is the most sterically demanding ligand.

Stereospecific syntheses of functionalised iron alkyl complexes with a stereogenic metal center from an iron formyl precursor

Treatment of the stable formyl complex Fe(C 5Ph 5)(CO(PMe 3)(CHO) ( 1) with an excess of methyl triflate and subsequent addition of NH 4PF 6 produces the secondary carbene complexes [Fe( η 5−C 5Ph 5)(CO)(PMe 3)( = CHOMe)][PF 6] ( 2, 93%). Methyl lithium acts as a dealkylating reagent with 2 to regenerate 1 (81%). Treatment of methoxycarbene complex 2 with LiAlD 4 gives the methoxymethyl complex Fe( η 5−C 5Ph 5)(CO)(PMe 3)(CH 2OMe) ( 3) in 95% yield. Similarly, reaction of 2 with LiAlD 4 gives a 90:10 mixture of Fe( η 5−C 5Ph 5)(CO)(PMe 3)(CHDOMe) ( 3 d 1 , 80%) diastereoisomers. The carbene complex 2 reacts with MeONa to give the iron dimethylacetal complex Fe( η 5−C 5Ph 5)(CO)(PMe 3)(CH(OMe) 2 ( 4, 55%). The cyano(methoxy)methyl complex Fe( η 5−C 5Ph 5(CO)(PMe 3){CH( rmCN)(OMe)} ( 5, 85%) is obtained from the reaction of 2 1 equivalent of KCN. NMR analyses of the crude product revealed that complex 5 was formed as a 85:15 mixture of diastereoisomers. The carbene complex 2 reacts with TMSCCLi to afford a 90:10 mixture of diastereoisomers of the stable methoxy(trimethylsilyethynyl)methyl iron complexes Fe(C 5Ph 5)(CO)(PMe 3) {CH(OMe)(C  CTMS)} ( 6). After extraction and filtration 6 is isolated as a pure diastereoisomer in 63% yield.

ChemInform Abstract: Synthesis of the Ethyl Oxalyl Tetracarbonyl Iron Anion ((CO)4FeCOCO2Et)‐, Its Methylation at the Metal into (CO)4Fe(Me)(COCO2Et) and Further Carbon‐Carbon Coupling into Ethyl Pyruvate.

AbstractCoupling of the iron carbonyl complex (I) with ethyl oxalyl chloride (II) and subsequent metathesis with bis(triphenylphosphoranylidene)ammonium chloride (IV) produce the salt (V) which is methylated with methyl triflate (VI) at a low temperature to yield the methyliron complex (VII).

Mechanism of the formation of methyliron complexes by protonation of methoxymethyliron complexes

Addition of [(η 5-C 5H 5)Fe(CO)(PPh 3)CH 2OMe] to HBF 4 etherate generates [(η 5 -C 5H 5)Fe(CO)(PPh 3)CH 2] + BF 4 − which abstracts hydride from the starting complex to generate equimolar amounts of [(η 5 -C 5H 5)Fe(CO)(PPh 3)Me] and [(η 5 -C 5H 5)Fe(CO)(PPh 3)CH(OMe)] + BF 4 −.

Reverse methyl migration from a methyliron complex to trimethylaluminum forming an ionic complex [Fe(dmpe) 2(acac)] +[AlMe 4] −

A stable cationic iron(II) complex [Fe(dmpe) 2(acac)] +[AlMe 4] − ( 1) (dmpe = 1,2-bis(dimethylphosphino)ethane, acac = 2,4-pentanedionato ligand) has been prepared by the reaction of Fe III(acac) 3 with AlMe 3 in the presence of dmpe. The tetramethylaluminate anion is considered to be formed by the methyl back transfer reaction from Fe to AlMe 3. Ion exchange of 1 with NaBPh 4 affords [Fe(dmpe) 2(acac)] + BPh 4 − in a high yield. These complexes have been characterized on the basis of 1H and 31P 1H NMR and IR spectroscopy, elemental analysis and by chemical reactions.

Preparation and properties of methyliron complexes with tertiary phosphine ligands and their decomposition pathways through the formation of carbenoid intermediates

Reaction of Fe(acac) 3, AlMe 2(OEt) and 1,2-bis(diphenylphosphino)ethane (dpe) gives a new dimethyliron complex, Fe(CH 3) 2(dpe) 2 (I). Complex I is unstable in solution and gives a methyliron complex containing an ortho-metallated ring, Fe(CH 3)(dpe) {Ph 2PCH 2CH 2PPh( o-C 6H 4)} (II) with liberation of methane. On thermal decomposition and treatment with CH 2Cl 2 compound I liberates ethylene, the formation of which suggests the intermediacy of carbenoid complexes. Reactions of I with H 2 or D 2, carbon dioxide and phenylacetylene yield FeH 2(dpe) 2 · C 6H 6 (IV) or FeD 2(dpe) 2 · C 6H 6 (VI), Fe(OOCCH 3)(CO 2) m (py) n (VII) and FeH(CCPh)(dpe) 2 (VIII), respectively. I initiates the polymerization of acrylonitrile. Employment of PPhMe 2 instead of dpe in the reaction of Fe(acac) 3 and AlMe 2(OEt) gave a new methylbis(acetylacetonato)iron(III) complex, Fe(CH 3)(acac) 2(PPhMe 2) (V). I and V react with carbon monoxide to yield acetone.

Preparation of dimethylbis(diphenylphosphinoethane)iron(II) and its decomposition pathways involving the formation of carbenoid intermediates

Reaction of Fe(acac)3, Me2AIOEt, and Ph2– PCH2CH2PPh2(dpe) gives a new methyliron complex, FeMe2(dpe)2 which on thermal decomposition and treatment with CH2Cl2 liberates ethylene, the formation of which suggests the intermediacy of carbenoid complexes.

New acetyl- and methyl-iron complexes

Several oxidative addition reactions of alkyl halides with derivatives of iron carbonyl have been undertaken at varying degrees of substitution, basicity and bulkiness of phosphine ligands. Only trimethylphosphine leads to a stable trans-iodoacetyl derivative which decarbonylates to give the cis-iodo-methyl derivative of di- carbonylbis(trimethylphosphine)iron. Methyl migration mechanism to the nearest CO during carbonylation reaction has been confirmed. The experimental evidence suggests that the reactivity of trigonal bipyramidal iron complexes depends on the negative charge associated with the remaining carbonyl ligands, and on the bulkiness of the phosphine ligands.