Friedrich-Wilhelm Grevels

Friedel–Crafts alkylation of ferrocene with Z-cyclooctene and cyclohexene

Abstract Cycloalkylated ferrocene derivatives, potentially useful as liquid burning rate modifiers for the HTPB/AP-based composite rocket propellants, were synthesized by the Friedel–Crafts alkylation of ferrocene with Z -cyclooctene or cyclohexene in the presence of AlCl 3 as a Lewis acid catalyst. The reaction with Z -cyclooctene yields a mixture of main products containing up to four C 8 H 15 substituents, each of which exists in several isomeric forms, as recognized by MS and GC–MS techniques. Two isomeric monosubstituted products, cyclooctylferrocene and (1-methylcycloheptyl)ferrocene, isolated by means of preparative GC, were identified by 13 C-NMR spectroscopy. In the case of cyclohexene, cyclohexylferrocene and a 2:1 mixture of 1,1′-dicyclohexylferrocene and 1,3-dicyclohexylferrocene were isolated and identified by MS and 13 C-NMR spectroscopy.

Pentacarbonyl (η2-cis-cyclo-octene)chromium: photochemical synthesis of a useful Cr(CO)5 transfer reagent

(η2-olefin)nCr(CO)6-n conplexes result from the photoreactions of Cr(CO)6 with cis-cyclo-octene (n = 1) and trans-cyclo-octene (n = 1, 2); (n = 1,2); (η2-cis-cyclo-octene)Cr(CO)5, isolated as a yellow solid, is labile in solution and serves as a useful Cr(CO)5 transfer reagent to produce various LCr(CO)5 derivatives, including the isotopically labelled hexacarbonyl, Cr(CO)5(13CO).

Verknüpfung von 1,3-dienen mit acrylsäuremethylester durch photochemische umsetzung mit pentacarbonyleisen ☆

Abstract Pentacarbonyliron and methyl acrylate/1,3-diene (2,3-dimethylbutadiene, isoprene, butadiene) mixtures react photochemically via diene—Fe(CO)3 and methyl acrylate—Fe(CO)4 to give products in which a methyl acrylate—diene adduct is 1,4,5,6-η-coordinated to the Fe(CO)3 moiety. (η2-diene)(η2-methyl acrylate)Fe(CO)3 is proposed to be an intermediate.

Synthesis of metal-rich metallaborane clusters. Evidence for a mechanism involving fragment condensation

Abstract A mechanistic hypothesis of metallaborane cluster build-up by the condensation of metal and boron containing fragments, which is supported by circumstantial evidence from previous work, suggests improved routes to the synthesis of ferraboranes. This work describes two new approaches consisting of the examination of two precursors with properties consistent with such a hypothesis. The first precursor, a neutral mononuclear dimethyl sulfide substituted iron tetracarbonyl, Fe(CO) 4 SMe 2 , is a new compound and the high yield synthesis and structural characterization of it are reported. This compound provides a better route to the ferraborane Fe 2 (CO) 6 B 2 H 6 than those presently known and is an isolatable, alternate source of the Fe(CO) 4 fragment. The second precursor, Fe(CO) 3 (cco) 2 , where cco is η 2 - cis -cyclooctene, is a known, ready source of the Fe(CO) 3 fragment. The reaction of Fe(CO) 3 (cco) 2 with BH 3 sources at low temperatures results in good yields of known ferraboranes and a product distribution that depends primarily on the ratio of boron to iron in the reactants. Both of these results support a mechanism for metallaborane cluster formation involving rapid metal carbonyl fragment condensation as a principal mechanistic component.

[η-(trans-1,2-dihalogenäthylen)]-tetracarbonyleisen-komplexe: thermische umwandlung in μ-[1-η: 1-2-η(trans-2-halogenvinyl)]-μ-halogen-bis(tricarbonyleisen)-(FeFe)-komplexe und weitere enthalogenierungsreaktionen

trans-1,2-Dihalogenoethylenes react with enneacarbonyldiiron in benzene to give the binuclear complexes μ-[trans-(CHXCH)]-μ-(X′)[Fe(CO)3]2 (III). The initially formed olefin-tetracarbonyliron complexes [trans-(CHXCHX′)]Fe(CO)4 undergo insertion of a second [Fe(CO)4] into a carbon—halogen bond finally leading to III. Some reactions of III occur with elimination of the halogen from the vinyl group to yield products which are also available from reactions of acetylene with carbonyliron complexes.

Chemical synthesis with metal Atoms. Cyclodimerization of norbornadiene via nickela-cyclopentane intermediates.

Abstract The catalytic cyclodimerization of norbornadiene by reaction with nickel atoms has been re-investigated. Nickela-cyclopentane derivatives are formed in the presence of α,α′-dipyridyl, α,α′-dipyridyl- exo-trans-endo -3-nickela-pentacyclo[9.2.1.1 5,8 0 2,10 .0 4,9 ]-pentadeca-6,12-diene being the major component. By contrast, the catalytic dimerization leads predominantly to the exo-trans-exo isomer of pentacyclo[8.2.1.1 4,7 .0 2,9 .0 3,8 ] tetradeca-5,11-diene. A norbornadiene cyclotrimer of exo-trans-exo-trans-exo structure is subsequently formed.

(Diethyl muconate)(1,4-diaza-1,3-diene)carbonyliron complexes: syntheses, spectra, and structure

Three examples of a new type of mixed (1,3-diene)(1,4-diaza-1,3-diene)carbonyliron complexes have been prepared. The diene ligand is diethyl muconate, trans , trans -H 5 C 2 OOCCHCHCHCHCOOC 2 H 5 , and the 1,4-diaza-1,3-diene (DAD) ligands are 2,2′-bipyridyl (BIPY) and the Schiff bases 2-benzoylpyridineanil (BPA) and 2-benzoylpyridine- p -methoxyanil (BPpMA). The complexes were made by thermal substitution of one diene ligand of bis(muconate)carbonyliron by the respective DAD ligands, and photochemically from (muconate)tricarbonyliron and DAD by substitution of two CO ligands. The structure of (muconate)(BIPY)Fe(CO) (I) was established by an X-ray analysis (cell data: a = 9.648(2) », b = 11.422(2) », c = 19.080(2) », β = 100.77(2)°; space group P2 1 / n , R = 0.048). The complex approximates to a square pyramid with one of the BIPY nitrogen atoms occupying the apical position. IR, UV, and mass spectra are reported. The 1 H and 13 C NMR spectra reveal the unsymmetrical structure. The complexes II (with BPA) and III (with BPpMA) are mixtures of isomers. The spectral data indicate structures analogous to I.

Ground and electronically excited states of Cr(CO)4(bipyridine): energy factored force field analysis of CO stretching vibrations and resonance Raman study

Abstract IR spectra of Cr(CO) 4 (bipyridine) and its 13 CO-containing isotopomers were used to calculate all the stretching and interaction CO force constants and the normal coordinates of the CO stretching vibrations. Resonance Raman (rR) spectra of Cr(CO) 4 (bpy) were measured and compared with the Fourier transform Raman spectra. The most resonance enhanced Raman bands belongs to the ring-deformation vibrations of the bpy ligand and the A 1 ν(CO) vibration at 2004 cm −1 . The rR spectral pattern confirms a localized Cr → bpy metal-to-ligand charge transfer (MLCT) character of the electronic transition responsible for the visible absorption band. It is shown that the MLCT excitation also affects the bonding within the Cr(CO) 4 molety. Of the two A 1 ν(CO) vibrations, only the one at higher frequency (A 1 2 , 2004 cm −1 ) gives rise to a resonance enhanced Raman band. Analysis of this effect, based on the energy factored force field (EFFF) calculated normal coordinates of both symmetric ν(CO) vibrations, shows that the MLCT excitation affects the CO bonds in both the axial and equatorial CO ligands, the influence on the axial ligands being larger. The Raman band due to the A 1 1 symmetric ν(CO)_vibration is not resonance enhanced because of an out-of-phase coupling between the symmetric vibrations of the axial and equatorial pairs of CO ligands. Raman bands due to CrC stretching and CrCO bending vibrations, apparently coupled with the vibrations of the Cr(bpy) moiety, were identified by the 13 CO isotope effect and found to be resonance enhanced.

Dynamics of metal carbonyls on the infrared time scale : coalescence of CO stretching vibrational bands.

Abstract The variable-temperature IR spectra of (η 4 -norbornadiene)Fe(CO) 3 and related complexes reveal a coalescence phenomenon involving the CO stretching vibrational bands. This is interpreted in terms of fast CO site exchange, rapid enough to equalize the CO force field parameters. A preliminary line shape analysis yields E a ≅ 1.5 kcal mol −1 .

Carbonyl(1,4-diaza-1,3-dien)(1,3-dien)eisen-komplexe: photochemische darstellung über tricarbonyl(1,4-diaza-1,3-dien)eisen

Abstract Photolysis of tricarbonyl(1,4-diaza-1,3-diene)iron complexes in the presence of dienes (butadiene, 2,3-dimethylbutadiene, cyclohexadiene-1,3) yields the title compounds, liberating 2 moles of C O. Imines or Schiff bases of 1,2-dicarbonyl compounds and of 2-acylpyridines are suitable 1,4-diazadiene ligands, DAD, in the starting tricarbonyl complexes. The photoreaction consists of two consecutive steps, the first of which is thermally reversible. According to the spectral data (IR, 1 H NMR and UV-vis) the compounds have a square pyramidal geometry around the central iron atom with basal/basal coordination of DAD and diene. This contrasts the N , N ′ apical/basal coordination of the DAD ligands in the previously described compounds with diethyl muconate as the diene ligand.