Reaction of Tricarbonyl(η3-allyl)iron(0) Anions with Bromine

The addition of reactive carbanions to tricarbonyl(η⁴-1,3-diene)iron(0) complexes proceeded at 23°C to give putative tricarbonyl(η³-allyl)iron(0) anion complexes. Trapping of the reactive intermediates with bromine produced nucleophilic-substituted tricarbonyl(η⁴-1,3-diene)iron(0) complexes.     

Oxidation of Tricarbonyl (η1 η2-but-3-en-1-yl)iron(0)and Tricarbonyl (η3-allyl)iron(0) Anion Complexes with Dioxygen

The addition of reactive carbanions to tricarbonyl(η⁴-1,3-diene)iron(0) complexes proceeded at ?78 °C to give putative tricarbonyl(η¹,η²-but-3-en-1-y1)iron(0) anion complexes and at 25 °C to produce postulated tricarbonyl(η³-allyl)iron(O) anion complexes; trapping of reactive intermediates with dioxygen produced γ,δ-unsaturated acids and allylic alcohols, respectively.     

Multilayered iron complexes of metacyclophanes. 1H NMR behavior

Syntheses are described for a series of (η⁶-cyclophane)(η⁵cyclopentadienyl)iron(II) complexes, where the cyclophane moiety is anti-[2.2]metacyclophane, anti-4,12-dimethyl[2.2]metacyclophane, anti-4,12-dimethyl-7,15-dimethoxy[2.2]metacyclophane, and [2.2](2,5)thiophenophane. The triple-layered complexes η⁶,η⁶-anti-[2.2]metacyclophane)bis[(η⁵-cyclopentadienyl)iron(II)] bis(hexafluorophosphate) and (η⁶,η⁶-anti-4,12-dimethyl[2.2]metacyclophane)bis[(η⁵-cyclopentadienyl)iron(II)] bis(hexafluorophosphate) were also prepared. The NMR spectra of these compounds provide a useful insight into the nature of the iron-cyclophane bonding.     

Reaction of tricarbonyl[(1-4-η)-2-methoxy-5-vinylidene-cyclohexa-1,3-diene]iron derivatives with carbene: (2+1) cycloaddition for the rapid synthesis of spiro[2,5]octane

Tricarbonyl[(1-4-η)-2-methoxy-5-methylene-cyclohexa-1,3-diene]iron (1a) and tricarbonyl[(1-4-η)-2-methoxy-5-isopropylene-cyclohexa-1,3-diene]iron (1b) complexes are unstable 4-vinylidene cyclohexanone equivalents and these react regio- and stereoselectively with carbenes and metallocarbenes to give spiro[2,5]octane ring system. The (2+1) cycloaddition reaction provides a rapid entry into spiro[2,5]octane ring system. In cases where the carbene and metallocarbene contain a good bulky leaving group or an electron-withdrawing group, the cyclopropane ring-opening products are obtained.     

Cyclodimerization of 1-(Dimethoxyniethyl)-5,6-dimethylidene-7-oxa-bicyclo[2.2.1]hept-2-ene Induced by Nonacarbonyldiiron. Crystal Structure of (1RS, 2SR, 3RS, 4RS, 4aRS, 9aSR)- Tricarbonyl[C, 2,3, C-η-(1,4-epoxy-1,5-bis(dimethoxymethyl)-2,3-dimethylidene-1,2,3,4,4a,9,9a,10-octahydroanthracene)]iron

The transition-metal-carbonyl-induced cyclodimerization of 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene is strongly affected by substitution at C(1) While 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept–2-ene-l-methanol ( 7 ) refused to undergo [4 + 2]-cyclodimerization in the presence of [Fe₂(CO)⁹] in MeOH, 1-(dimethoxymethyl)-5,6-di-methylidene-7-oxabicyclo[2.2.1]hept-2-ene ( 8 ) led to the formation of a 1.7:1 mixture of ‘trans’ ( 19, 21, 22 ) vs. ‘cis’ ( 20, 23, 24 ) products of cyclodimerization together with tricarbonyl[C, 5,6, C-η-(l-(dimethoxymethyl)-5,6-di-methylidenecyclohexa-1,3-diene)]iron ( 25 ) and tricarbonyl[C,3,4, C-η-(methyl 5-(dimethoxymethyl)-3,4-di-methylidenecyclohexa-1,5-diene-l-carboxylate)]iron ( 26 ). The structures of products 19 and of its exo ( 21 ) and endo ( 22 ) [Fe(CO)₃(1,3-diene)]complexes) and 20 (and of its exo ( 23 ) and endo (24) (Fe(CO)₃(1,3-diene)complexes) were confirmed by X-ray diffraction studies of crystalline (1RS, 2SR, 3RS, 4RS, 4aRS, 9aSR)-tricarbonyl[C, 2,3, C-η-(1,4-epoxy-1,5-bis(dimethoxymethyl])-2,3-dimethylidene-1,2,3,4,4a,9,9a,10-octahydroanthracene)iron ( 21 ). In the latter, the Fe(CO)₃(1,3-diene) moiety deviates significantly from the usual local C_s symmetry. Complex 21 corresponds to a ‘frozen equilibrium’ of rotamers with η-alkyl, η³-allyl bonding mode due to the acetal unit at the bridgehead centre C(1).     

Thermodynamic and kinetic parameters associated with the fluxional behavior of 2-methyl- and 2,6-dimethyltroponeiron tricarbonyl complexes

The kinetic and thermodynamic parameters for regioisomerisation of 2-methyl- and 2,6-dimethyl-derivatives of tricarbonyl[η⁴-tropone]iron complexes have been studied by ¹H NMR spectrometry over a range of 40 °C. Regioisomerisation of these complexes proceeds by an intramolecular first-order process and results in the almost complete conversion of the less stable complexes (4, 8) to more stable regioisomers (1, 5). The activation energies and half lifes for the conversion (4 → 1) and (8 → 5) were found to be ΔG^#=92 kJ mol⁻¹; τ_1/2=12.8 h, and ΔG^#=107 kJ mol⁻¹; τ_1/2=26.8 h, respectively, at 23 °C. Complex 1 reacts with (1R,2S,5R)-menthol in sulphuric acid solution, followed by neutralisation with sodium carbonate to give a separable mixture of diastereomeric tricarbonyl[(2,3,4,5-η)-(1R^′,2S^′,5R^′)-6-menthyloxy-2-methyltropone]iron complexes, 9 and 10. The corresponding dimethylated complex 5 fails to react under these conditions.     

Indenyl and fluorenyl transition metal complexes : VII. Innersphere “ricochet” rearrangements on alkylation of η5-indenyl- and η5-fluorenyltricarbonylchromate anions

Alkylation of K[η⁵-C₉H₇Cr(CO)₃] (Xa) with CH₃I and C₆H₅CH₂Br leads to σ-alkyl derivatives of η⁵-C₉H₇Cr(CO)₃Alk type. These complexes undergo innersphere “ricochet” rearrangement, with the alkyl group being shifted to the endo position at C(1) and the chromium tricarbonyl group shifted to the benzene nucleus. The structure of the product of such a rearrangement in the case of η⁵-C₉H₇(CO)₃CrCH₂C₆H₅, i.e. (1-benzyl-3a,4-7,7a-η⁶-indene)chromium tricarbonyl (XVIII), is established by a low temperature X-ray study, indicating an endo position for the benzyl radical.On alkylation of equilibrium tautomeric mixtures of η⁵- and η⁶-fluorenylchromium tricarbonyl anions XIa ? XIb under similar conditions, the η⁵-anion (Xa) yields a σ-alkyl derivative, which is rearranged to (9-endo-alkyl-1-4,4a,9a-η⁶-fluorene)chromium tricarbonyl. Electrophilic attack of the η⁶-anion (XIb) takes place on the outer side at C(9) and leads to a corresponding 9-exo-alkyl derivative.     

Organometallic polymers containing tricarbonyl(η4-diene)-ruthenium(0) and -iron(0) as pendant groups

Vinyl ethers containing tricarbonyl(14-η⁴-1,3-pentadiene)-ruthenium(0) and -iron(0) species were prepared utilizing selective dienylation with penta-dienylpotassium and were polymerized with cationic initiators to give high molecular weight polymers. The diene-metal moieties were converted into tricarbonyl(13-η³-allyl)metal species by protonation with dry HCl. Tricarbonyl(3-allyl-14-η⁴-1,3-pentadiene)iron(0) also undergoes cationic polymerization but the presence of its isomer, tricarbonyl(3-propenyl-14-η⁴-1,3-pentadiene)iron(0) inhibits the polymerization.     

Ironcarbonyl Complexes of 5,6-Dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene Derivatives. Synthesis of Substituted Tricarbonyl(ortho-quinodimethane)iron Complexes and 2-Indanones

The l-dimethoxymethyl-5,6-dimethyldene-7-oxabicyclo[2.2.1]hept-2-ene ( 9 ) has been prepared. On treatment with Fe₂(CO)₉, the endocyclic double bond C(2)?C(3) was coordinated first giving the corresponding exo-Fe(CO)₄ complex 10 . The latter reacted with Fe₂(CO)₉ and afforded cis-heptacarbonyl-μ-[1RS,2SR,3RS,4SR,5RS,6SR-2,3-η: C5,6,C-η-(1-(dimethoxymethyl)-5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene)]diiron ( 11 ) as a major product. On heating, 11 underwent deoxygenation of the 7-oxabicyclo[2.2.1]heptene moiety yielding tricarbonyl[C,5,6,C-η-(1-(dimethoxymethyl)-5,6-dimethylidenecyclohexa-1,3-diene)]iron ( 13 ). In MeOH, a concurrent, regioselective methoxycarbonylation was observed giving tricarbonyl[C,3,4,C-η-(methyl 5-(dimethoxymethyl)-3,4-dimethylidenecyclohexa-1,5-diene-1-carboxylate)]iron ( 14 ). Oxidative removal of the Fe(CO)₃ moiety in 13 and 14 did not afford the expected ortho-quinodimethane derivatives but led to CO insertions giving 2,3-dihydro-2-oxo-1Hindene-4-carbaldehyde ( 20 ) and methyl 7-formyl-2-3-dihydro-2-oxo-lH-indene-5-carboxylate ( 21 ), respectively.     

Complexation of [2.2]paracyclophane with an (η5-cyclopentadienyl)iron+ moity: mono- and di-cations

The reaction of [2.2]paracyclophane with ferrocene in the presence of AlCl₃ and Al/powder gives the new compounds [1-6-η-[2.2]paracyclophane- (η⁵-cyclopentadienyl)iron]⁺[PF₆] and [1-6-η; 9-14-η-[2.2]paracyclophane- [(η⁵-cyclopentadienyl)iron]₂]²⁺[PF₆]₂ in high yields. The species have been characterized by elemental analysis, and by ¹H and ¹³C NMR spectroscopy.     

Synthesis and 1H-, 13C-, and 57Fe-NMR spectra of mono- and bis[tricarbonyl(η4-diene)iron], and (η3-allyl)tetracarbonyliron trifluoroborate complexes

A variety of mono- and bis[Fe(CO)₃(η⁴-diene)] complex with alky, CH₂OH, CHO, COCH₃, COOR, and CN substituents on the 1,3-diene system have been synthesized. Dienes with a (Z)-configuration terminal Me group show steric inhibition of metal complexation resulting in lower yields and formation of tetracarbonyl(η²-diene) and tricarbonyl(η⁴-heterodiene) complexes as additional products. Regioselective attack by C-nucleophiles at the carbonyl C-atoms of the functional group with or without concomitant 1,3 mogration of the Fe(CO)₃ group was used to synthesize polyenes and isoprenoid building blocks as mono- or dinucliar Fe(CO)₃ complexes. Wittig-Horner-type reactions of Fe(co)₃-complexed synthons result in sterospecific formation of (E)-configurated olefins. The ¹H-, ¹³C- and ⁵⁷Fe-NMR spectra of olefinic and allylic organoiron complexes are reported, H,H,C,H, and C,C coupling constants have been evaluated and are analyzed in terms of the geometry of the coordinated diene. The results are corroborated by the crystal structure of tricarbonyl[3–6-η-((E)-6-methyl-3,5-heptadiene-2-one)]iron( 34 ) which shows an unusual distortion of the (CH₃)₂C = group, The ⁵⁷Fe-NMR chemical shifts extend over the ranges of 0–600 ppm for [Fe(CO)₃(η⁴-diene)] complexes, 780–1710 ppm for [Fe(CO)₄(η³-allyl)] [BF₄] and [FeX(CO)₃(η⁴-allyl)] complexes, and 1270–1690 ppm for [Fe(CO)₃(η⁴-enone)] complexes, relative to Fe(CO)₅.     

Complexes du type (η3 : η1-allylcarbonyl)fer tricarbonyle : III. Reactions de decomplexation

Several functionalized (η³ : η¹-allylcarbonyl)iron tricarbonyl complexes obtained from electrophilic gem-dimethylcyclopropenes were oxidized with trimethylamine oxide or iron trichloride in methanol. The products which were obtained in good yields show that these complexes can chemically be regarded as valuable vinylketene precursors, which allows their rapid structure determination.     

Tricarbonyl(N,N-Disubstituted-Cyclohexadienecarboxamide)iron Complexes: Investigation of the Possible Intramolecular Interaction between the Iron Center and the Amide Substituent

Direct reaction of iron pentacarbonyl with 1-N,N-disubstituted-cyclohexa-2,5-dicnecarboxamide and 1-N,N-disubstituted-cyclohexa-1,3-dienecarboxamide mixture (in which the disubstkuted group is diethyl or diphenyl) gave the isomeric tricarbonyl iron complexes of 2-N,N-disubstituted-1,4-η-cyclohexa-1,3-dienccarboxamide (1), 1-N,N-disubslituted-1,4-η-cyclohexa-1,3-dienecarboxamide (2), and 5-N,N-disubstituted-1,4-η-cyclohexa-1,3-dienecarboxamide (3) and tricarbonyliron complexes of l-N,N-disubstituted-cyclohexenecarboxamide (4). These complexes were separated and characterized by IR, UV-VIS, ¹H NMR, elemental analysis, and mass spectra. Only 1 isomerized to give 2 under acidic conditions; both 1 and 2 undergo hydride abstraction with triphenylmethyl hexafluorophosphatc. Complexes 3, undergo neither isomcrization nor hydride abstraction. According to the spectral data, the possible interaction between carboxamide and iron carbonyl moiety was investigated. The irreversible electrochemical behavior of these complexes were studied.     

Photochemische reaktionen von übergansmetall-olefinkomplexen: III. [4 + 6]-cycloaddition konjugierter diene an hexacarbonyl-μ-η6:6(-1,1′-bi(2,4,6-cycloheptatrien-1-yl)dichrom(O)

UV irradiation of hexacarbonyl-μ-η^6:6-1,1′-bi(2,4,6-cycloheptatrien-1-yl)dichromium(O) (I) in THF in the presence of 1,3-butadiene (A), E-1,3-pentadiene (B) and EE-2,4-hexadiene (C) causes preferentially a twofold [4 + 6]-cycloaddition and formation of the hexacarbonyl-μ-2–5 : 8.9-η-2′–5′ : 8′,9′-η-11,11′-bi(bicyclo-[4.4.1]undeca-2,4,8-trien-11-yl)dichromium(O) complexes (IVA–IVC). Partial decomplexation after the first [4 + 6]-cycloaddition yields isomeric tricarbonyl-2–5:8,9-η- (IIA–IIC) and tricarbonyl-2′–7′-η-{11-(2′,4′,6′-cycloheptatrien-1′-yl)bicyclo[4.4.1]undeca-2,4,8-triene}chromium(O) complexes (IIIA–IIIC). With 2,3-dimethyl-1,3-butadiene (D) mainly dicarbonyl-2–6 : 2′–4′-η-{1-(2′,3′-dimethyl-3′-buten-1′,2′-diyl)-7-(8″,9″-dimethylbicyclo[4.4.1]undeca-2″, 4″,8″-trien-11″-yl)cyclohepta-3,5-dien-2-yl}chromium(O) (VD) besides small amounts of pentacarbonyl-μ-2–6 : 2′–4′-η-2″–7″-η-{1-(2′,3′-dimethyl-3′-buten-1′,2′-diyl)-7-(2″, 4″,6″-cycloheptatrien-1″-yl)cyclohepta-3,5-dien-2-yl}dichromium(O) (VID) and tricarbonyl-2′-7′-η-{11-(2′,4′,6′-cycloheptatrien-1′-yl)-8,9-dimethyl-bicyclo[4.4.1]undeca-2,4,8-triene}-chromium(O) (IIID) is obtained. VD adds readily CO to yield tricarbonyl-2–5 : 8,9-η-11,11′-bi(8,9-dimethyl-bicyclo[4.4.1]undeca-2,4,8-trien-11-yl)chromium(O) (VIID). Finally D adds to VID under formation of pentacarbonyl-μ-2–6 : 2′–4′-η-2″–5″ : 8″,9″-η-{1-(2′,3′-dimethyl-3′-buten-1′,2′-diyl)-7-(8″,9″-dimethyl-bicyclo[4.4.1]- undeca-2″,4″,8″-trien-11″-yl)cyclohepta-3,5-dien-2-yl}dichromium(O) (VIIID). From IVA–IVC the hydrocarbon ligands (IXA–IXC) can be liberated by P(OCH₃)₃ in good yields. The structures of the compounds IIA–IXC were determined by IR     

Nucleophilic Addition Reactions of Tricarbonyl [η5−1-(Phenylsulfonyl)cyclohexadienyl]iron(I) Complex

Hydride abstraction of tricarbonyl[η⁴-1-(phenylsulfonyl)-1,3-cyclohexadiene]iron(0) complex 2 with Ph₃C⁺PF₆^? regiospecifically provided the title compound 3 in excellent yield. Cationic complex 3 could react with a variety of nucleophiles in good yields. Soft nucleophiles prefer to attack at the C-5 position, whereas hard nucleophiles such as methyllithium and the enolate of ethyl acetate gave the C-5 as well as the C-2 addition products. Some synthetic applications of the addition products were also studied.     

(Tetragermacyclobutadiene)ruthenium tricarbonyl [η4-(But 2MeSi)4Ge4]Ru(CO)3

Tetrakis(di-tert-butylmethylsilyl)tetragermacyclobutadiene]ruthenium tricarbonyl [η⁴-(Bu^t ₂MeSi)₄Ge₄]Ru(CO)₃ is synthesized. This analogue of well-known cyclobutadiene transition metal complexes bears a tetragermacyclobutadiene derivative as ligand. The structure and spectroscopic parameters of the complex are compared with those of its iron-containing analogue [η⁴-(Bu^t ₂MeSi)₄Ge₄]Fe(CO)₃. Based on experimental data and results of quantum chemical calculations, it is shown that the π-donating ability of ligands increases upon replacement of carbon atoms in the cyclobutadiene moiety by silicon or germanium atoms, tetrasilacyclobutadiene and tetragermacyclobutadiene being comparable in π-donating activity.     

(1,3-Diformylindenyl)cyclopentadienyl ruthenium derivatives

The reaction of [CpRu(CH₃CN)₃][PF₆], [Cp*RuCl] _n , and [Cp^FRuCl]n with 1,3-diformylindene results in the predominant formation of zwitter-ionic arene-cyclopentadienyl complexes {η⁶-1,3-(CHO)₂C₉H₅}RuCp (Cp = C₅H₅), {η⁶-1,3-(CHO)₂C₉H₅}RuCp* (Cp* = C₅Me₅), and {η⁶-1,3-(CHO)₂C₉H₅}RuCp^F (Cp^F = C₅Me₄CF₃), respectively. The ruthenocenes {η⁵-1,3-(CHO)₂C₉H₅}RuCp, {η⁵-1,3-(CHO)₂C₉H₅}RuCp*, and {η⁵-1,3-(CHO)₂C₉H₅}RuCpF were synthesized by the reaction of 1,3-diformylindenyl potassium with [CpRu(CH₃CN)₃][PF₆], [Cp*RuCl] _n , and [Cp^FRuCl] _n .     

Synthesis of some heterocyclic skeletons via organoiron complexes. Crystal and molecular structure of (5a,6,7,8,9,9a-η6-1,4-benzoxathiino[3,2-b]pyridine)(η5-cyclopentadienyl)iron hexafluorophosphate

Synthesis of the heterocyclic skeletons of some biologically active compounds from (η⁶-o-dichlorobenzene)(η⁵-cyclopentadienyrl)iron hexafluorophosphate in a two step procedure is described. Cyclopentadienyliron hexafluorophosphate complexes of 1,4-benzodioxino[2,3-b]pyridine, 1,4-benzoxathiino[3,2-b]pyridine, 10H-pyrido[3,2-b]benzoxazine, benzo[b]naphtho[2,3-e][1,4]dioxin, 4-methylbenzo[b]benzopyran-2-one[7,6-e][1,4]dioxin and benzo[b]anthracen-9,10-diono[1,2-e][1,4]dioxin were isolated and characterized. Upon pyrolytic sublimation of these complexes the free heterocycles were obtained and characterized. (η⁶-1,4-Benzoxathiino[3,2-b]pyridine)(η⁵-cyclopentadienyl)iron hexafluorophosphate crystalizes in the orthothombic system, space group Pbca; the dihedral angle between the planes of outer rings was found to be 176.8 (1).     

(η3: η1 allylcarbonyl)iron tricarbonyl complexes. I. Transformation of complexes from electrophilic gem-dimethylcyclopropenes into functionalized isoprenic diene-iron tricarbonyl complexes by thermolysis or photolysis

Electrophilic gem-dimethyl cyclopropenes react with diiron enneacarbonyl to give (η³: η¹ allylcarbonyl)iron tricarbonyl complexes. These complexes, bearing in this work electron withdrawing substituents, are shown to be rather labile thermally and photochemically, leading easiyl to isoprenic diene-iron tricarbonyl complexes.     

Syntheses and structures of iron carbonyl complexes derived from N-(5-methyl-2-thienylmethylidene)-2-thiolethylamine and N-(6-methyl-2-pyridylmethylidene)-2-thiolethylamine

The reaction of N-(5-methyl-2-thienylmethylidene)-2-thiolethylamine (1) with Fe₂(CO)₉ in refluxing acetonitrile yielded di-(μ₃-thia)nonacarbonyltriiron (2), μ-[N-(5-methyl-2-thienylmethyl)-η¹:η¹(N);η¹:η¹(S)-2-thiolatoethylamido]hexacarbonyldiiron (3), and N-(5-methyl-2-thienylmethylidene)amine (4). If the reaction was carried out at 45 °C, di-μ-[N-(5-methyl-2-thienylmethylidene)-η¹(N);η¹(S)-2-thiolethylamino]-μ-carbonyl-tetracarbonyldiiron (5) and trace amount of 4 were obtained. Stirring 5 in refluxing acetonitrile led to the thermal decomposition of 5, and ligand 1 was recovered quantitatively. However, in the presence of excess amount of Fe₂(CO)₉ in refluxing acetonitrile, complex 5 was converted into 2-4. On the other hand, the reaction of N-(6-methyl-2-pyridylmethylidene)-2-thiolethylamine (6) with Fe₂(CO)₉ in refluxing acetonitrile produced 2, μ-[N-(6-methyl-2-pyridylmethyl)-η¹ (N_py);η¹:η¹(N); η¹:η¹(S)-2-thiolatoethylamido]pentacarbonyldiiron (7), and μ-[N-(6-methyl-2-pyridylmethylidene)-η²(C,N);η¹:η¹(S)-2- thiolethylamino]hexacarbonyldiiron (8). Reactions of both complex 7 and 8 with NOBF₄ gave μ-[(6-methyl-2-pyridylmethyl)-η¹(N_py);η¹:η¹(N);η¹:η¹(S)-2-thiolatoethylamido](acetonitrile)tricarbonylnitrosyldiiron (9). These reaction products were well characterized spectrally. The molecular structures of complexes 3, 7-9 have been determined by means of X-ray diffraction. Intramolecular 1,5-hydrogen shift from the thiol to the methine carbon was observed in complexes 3, 7, and 9.