Über den einfluss von chlor-substituenten auf die bildungstendenz und bindungsverhältnisse des tricarbonyl(buta-1,3-dien)eisen: Tricarbonyl(2,3-dichlorbuta-1,3-dien)eisen und tricarbonyl(2-chlorbuta-1,3-dien)eisen

Frequencies of carbonyl stretching vibrations and relative yields in syntheses of tricarbonyl(2,3-dichlorobuta-1,3-diene)iron and tricarbonyl(2-chlorobuta-1,3-diene)iron are discussed with respect to possible steric effects of chloro-substituents on the formation of tricarbonyl(hexachlorobuta-1,3-diene)iron.     

Kristall- und Molekülstruktur von tricarbonyl(η4-3,4-dimethyl-thiophen-1,1-dioxid)eisen

A single-crystal X-ray diffraction study of tricarbonyl(η⁴-3,4-dimethyl-thiophene-1,1-dioxide)iron has been made. Crystal data: space group P4₁2₁2; a  b  9.307(2), c  25.462(5) Å; Z  8. With 950 reflections [F_o > 3 σ(F_o)] the structure has been refined anisotropically (hydrogens isotropically) to R  0.026.In the compound 3,4-dimethylthiophene-1,1-dioxide is coordinated to iron by its diene system analogous to (butadiene)Fe(CO)₃. The sulfur atom is out-of-plane of the butadiene system (26.9°). This fact can be explained by intramolecular repulsion and by coordination effects. The three CO groups are directed towards the centres of greatest electron density in the ring. Hence one CO and the SO₂ group are in eclipsed conformation with a slight deformation due to OO repulsion of both groups. IR, ¹H NMR, and ¹³C NMR data are reported.     

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.     

Stereoselektive Synthesen von substituierten Tricarbonyl[tris(methylen)methan]eisen(0)-Komplexen

Stereoselective Syntheses of Substituted Tricarbonyl[tris(methylen)methan]iron(0) Complexes The complexes 3 , 9 , 10 , 22 , and 23 with one, two, and three Me substituents at the tris(methylen)methane moiety have been synthesized from the (acyloxy-1,3-diene)(tricarbonyl)iron(0) complexes 1 , 4 , 5 , 20 , and 21 , respectively, by ionic hydrogenation with BF₃ and Et₃SiH at ?78° in CH₂C1₂. These reductions are completely stereoselective, and their course can be predicted by assuming a dominant stereoelectronic control of the reaction. Formation of the carbocationic intermediates 11 from 4 and 12 from 5 , e.g., takes place only if the dissociating O? C bond is antiperiplanar to the donor C(β)? Fe bond. Fast H-transfer then converts the intermediate 11 to 9 and 12 to 10 . The configurations of 17 and 20 can be deduced from the structure of 22 and those of 18 and 21 from that of 23 . An X-ray structure determination of (1R,4S)camphanoate (?)- 13 derived from alcohol (?)- 7 confirms the configuration of 5 deduced above, The structures of the complexes 9 and 10 , 22 and 23 were determined by their unique NMR spectra. The diastereoisomeric complexes 6 and 7 have been synthesized from aldehyde 8 with MeMgI, the diastereoisomers 17 and 18 analogously from 16 or from methyl ketone 19 by reduction with LiAlH₄. Optically active starting materials (+)- 1 , (?)- 13 , (+)- 20 , and (+)- 21 gave, by ionic hydrogenation, the complexes (?)-(3R)- 3 , (+)-(2S,4S)- 10 , (?)-(R,R, S)- 22 , and (?)-(R,R,R)- 23 respectively, with known absolute configurations.     

Mass spectrometric study of tricarbonyl (eta(6)-phenyl methanols) of chromium(0)

A mass spectrometric study of several tricarbonyl (eta(6)-phenyl methanols) of chromium(0) was performed. Electron ionization (EI), chemical ionization (CI) and fast atom bombardment (FAB) mass spectra were acquired for each molecule, and compared in order to establish a general fragmentation pattern. The suggested pathways were investigated and confirmed by means of constant b/e linked scans and high resolution data. In addition a Hammett-McLafferty correlation for some peaks derived from the molecular ions was accomplished.     

Catalytic tail-to-tail dimerization of methyl acrylate using bis(triphenylphosphine)tricarbonyl ruthenium(0)

The complex Ru(CO)₃(PPh₃)₂ catalyzes the dimerization of methyl acrylate at 120–140°C to give tail-to-tail dimers containing predominantly dimethyl (E)-2-hexene-1,6-dioate together with small amounts of trimers and polymer. The reaction under hydrogen atmosphere selectively gave tail-to-tail dimers in improved yield without formation of trimers and polymer. Under these conditions a catalyst turnover number of 246 was obtained at 130°C in 6 h.     

Diastereoselective spiroketalization: stereocontrol using an iron(0) tricarbonyl diene complex

It has been demonstrated that an element of planar chirality can influence the formation of an adjacent spiroketal stereocenter. Appropriately functionalized enantiomerically pure 1- and 2-sulfinyl 1,3-dien-5-ones and their corresponding iron(0) tricarbonyl complexes (7, 17) have been prepared, and the derived spiroketals (8, 18) are made in good to excellent diastereoselectivity. A preliminary exploration of the combined effects of planar and central chirality upon the diastereoselectivity revealed matched and mismatched combinations (14).     

Reactions of tricarbonyl phosphine complexes of molybdenum(0) with mercury chloride

The reactions of tricarbonylphosphine complexes (bipy)(P)Mo(CO)₃, (bipy)= 2,2′-bipyridine and (P) = P(4-ClC₆H₄)₃, P(4-FC₆H₄)₃, P(4-CH₃C₆H₄)₃ and P(4-CH₃OV₆H₄)₃, with HgCl₂ give compounds of the type (bipy)₂Mo₂(CO)₆·HgCl₂ and (bipy)Mo(CO)₃(HgCl)(Cl), depending on the mol ratio of reactants employed. The reaction proceeds with elimination of the phosphine ligand and the coordination of HgCl₂ to molybdenum.A new tricarbonyl complex (bipy)(dppe)₂Mo₂(CO)₆ (dppe = 1,2-ethanediyl-bis(diphenylphosphine),

with the bidentate phosphine ligand, is prepared from the reaction of the (bipy)Mo(CO)₄ complex and dppe. The tricarbonyl-dppe derivative also reacts with HgCl₂ in a 1:1 mol ratio, to give (bipy)(dppe)₂Mo₂(CO)₆· 2HgCl₂ and (dppe)₃Mo₂(CO)₆·HgCl₂. An excess of mercuric chloride yields the compound (bipy)(dppe)₂Mo₂(CO)₆· 4HgCl₂.In addition, the (bipy)Mo(CO)₃(HgCl)(Cl) complex is isolated from the solution.     

Synthesis,structure, and quantum-chemical study of tricarbonyl(4-methoxybenzaldehyde)chromium(0)

The structure of tricarbonyl(4-methoxybenzaldehyde)chromium(0) was studied by X-ray crystallography. The crystals are orthorhombic, space group P2₁2₁2₁, a = 8.040(1) Å, b = 10.510(7) Å, c = 13.279(4) Å, V = 1122.1(8) ų, Z = 4. Quantum-chemical calculations predict that this compound can exist in the gas phase as two stable conformers with almost the same energies. Their mutual transformations are examined using the density functional theory.     

(Dihydropyridine)iron tricarbonyl complexes

(N-Carboalkoxy-1,2-dihydropyridine)iron tricarbonyl complexes have been isolated by treatment of either N-carboalkoxy-1,2 or -1,4-dihydropyridines with diiron ennecarbonyl. The organic ligand was liberated from these complexes by use of trimethylamine oxide.     

CC-kupplungen von CO2 mit 1,3-dienen an eisen(0)-komplexen; carboxylatbildung und folgereaktionen

1,3-Dienes react with CO₂ at ligand-iron(0) systems to form η³-allyl carboxylates. The dynamic allylic system is influenced by addition of further ligands such as phosphanes or maleic acid anhydride or acetic acid anhydride. The direction of this influence is shown on the basis of the products generated by protonolysis or insertion of CO₂. When substituted 1,3-dienes are used, the 1/1 coupling step is regioselective. For example, with 1,3-pentadiene and CO₂ only two η³-allyliron carboxylates in the molar ratio 1/1 are formed. This isomer ratio confirms that the coupling reaction is kinetically controlled.     

Synthesis and structural characterization of tricarbonyl 1-azahexa-1,3,5-triene iron(0) complexes

Transition Metal Chemistry -     

Ein (Phosphonioalkinyl)- und ein Acetyl(tetracarbonyl)eisen

A (Phosphonioalkinyl)- and an Acetyl(tetracarbonyl)iron From the reaction of 1,1,3,3-tetrakis(dimethylamino)-1λ⁵,3λ⁵-diphosphete, 1 , and Fe(CO)₅ {[bis(dimethylamino)phosphoryl-methyl]-bis(dimethylamino)phosphonioethinyl}(tetracarbonyl)iron, 4 , and {1,1,3,3-tetrakis(dimethylamino)-1,4-dihydro- 1λ⁵,3λ⁵-[1,3]diphosphetium-2-carbonyl}(tetracarbonyl)-iron, 5 , can be isolated as crystalline products. The nmr, mass and ir spectra of the two compounds as well crystal and molecular structures of 4 are reported. The bonding situation in compounds 4 and 5 are discussed in detail.