- Preparation process of tetramethyl cyclopentadiene
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The invention provides a preparation process of tetramethyl cyclopentadiene, which comprises the following steps: A) uniformly mixing tetramethyl cyclopentenone, alcohol and a catalyst to obtain a mixed solution; B) dropwise adding a NaBH4 solution into the mixed solution, and carrying out a reduction reaction to obtain a reaction mixed solution, wherein the NaBH4 solution is prepared from NaBH4, alcohol, NaOH and water; C) adding water into the reaction mixed solution, and extracting organic matters in the reaction mixed solution by using an extracting agent; and D) adding sulfuric acid into the organic matter extracted in the step C), and dehydrating to obtain tetramethyl cyclopentadiene. According to the reaction system disclosed by the invention, tetramethyl cyclopentenone is reduced into tetramethyl cyclopentene alcohol by sodium borohydride under a mild condition by adjusting the conditions such as the catalyst, the solvent, the reaction temperature and the reaction time, and tetramethyl cyclopentadiene can be prepared after dehydration.
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Paragraph 0053; 0056; 0057; 0060; 0061; 0064; 0065; 0068
(2021/05/01)
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- Preparation method 1, 2, 3, 4 - tetramethyl -1 and 3 - cyclopentadiene
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The invention relates to the technical field of chemical synthesis, in particular to a preparation method of 1, 2, 3, 4 - tetramethyl -1 and 3 - cyclopentadiene, which comprises A) carrying out a metal supported catalyst under the condition of hydrogen. 2, 3, 4, 5 -tetramethyl -2 - cyclopentene ketone and a solvent are subjected to hydrogenation reaction to obtain 2, 3, 4 and 5 -tetramethyl -2 - cyclopentanol. A metal supported catalyst comprises a solid support and a metal supported on the solid support. The metal element is selected from one or both of the VIII th main group elements. B) Under the action of a strong acid resin catalyst, 2, 3, 4 and 5 - tetramethyl -2 - cyclopentanol are subjected to dehydration reaction to obtain 1, 2, 3, 4 - tetramethyl -1 and 3 - cyclopentadiene. After the hydrogenation reaction is finished, only simple filtration removal is needed, solid waste liquid is not generated, acid is not needed for neutralization, waste acid water which is difficult to handle is not generated, and the product yield is high.
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Paragraph 0051; 0055-0073; 0076-0079
(2021/09/29)
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- Preparation method of 1, 2, 3, 4-tetramethyl-1, 3-cyclopentadiene
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The invention belongs to the technical field of chemical synthesis, and particularly relates to a preparation method of 1, 2, 3, 4-tetramethyl-1, 3-cyclopentadiene. The preparation method provided bythe invention comprises the following step: in the presence of a solid acid catalyst, carrying out dehydration reaction on 2, 3, 4, 5-tetramethyl-2-cyclopentenol in a solvent to obtain 1, 2, 3, 4-tetramethyl-1, 3-cyclopentadiene, wherein the solid acid catalyst comprises a strongly acidic resin catalyst and/or a solid superacid catalyst. According to the preparation method, 2, 3, 4, 5-tetramethyl-2-cyclopentenol is used as a raw material and is subjected to dehydration reaction under the action of a specific solid acid catalyst to obtain a target product (1, 2, 3, 4-tetramethyl-1, 3-cyclopentadiene). The preparation method provided by the invention can effectively inhibit the generation of by-products, the product is high in selectivity and easy to separate, no solid waste or waste acid water is generated, and good economic benefits and environmental benefits are achieved.
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Paragraph 0037; 0046-0080
(2020/06/30)
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- Tuning the photochemical properties of the fulvalene-tetracarbonyl-diruthenium system
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In a Molecular Solar-Thermal Energy Storage (MOST) system, solar energy is converted to chemical energy using a compound that undergoes reversible endothermic photoisomerization. The high-energy photoisomer can later be converted back to the parent compound and the excess energy is released as heat. One of the most studied MOST systems is based on fulvalene-tetracarbonyl-diruthenium, and this paper demonstrates, for the first time, the possibility to tune the photochemical properties of this system by positive steric hindrance working on the fulvalene unit.
- Lennartson, Anders,Lundin, Angelica,B?rjesson, Karl,Gray, Victor,Moth-Poulsen, Kasper
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supporting information
p. 8740 - 8744
(2016/06/09)
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- Ytterbium(III) Complexes Coordinated by Dianionic 1,4-Diazabutadiene Ligands
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A series of new Yb(III) complexes XYb(DAD)2-(L) (X = C5Me5, C5Me4H, N(SiMe3)2, tBuO; DAD = 2,6-R″2C6H3N=C(R′)-C(R′)=NC6H3R″2-2,6, R′ = H, Me, R″ = Me, iPr; L = thf, dme) coordinated by redox-active diazabutadiene ligands in dianionic form were synthesized and characterized. The half-sandwich complexes Cp#Yb(DAD)2-(THF) (Cp# = C5Me5, C5Me4H) were synthesized by the reactions of the ytterbocenes Cp#2Yb(THF)2 with the corresponding DADs in a 1:1 molar ratio. These reactions are accompanied by oxidation of the Yb(II) to Yb(III), cleavage of one Cp#-Yb bond, oxidation of cyclopentadienyl anion, and reduction of the diazabutadiene to dianionic form. It was found that the substituents by the DAD nitrogens (2,6-iPr2C6H3 vs 2,6-Me2C6H3) and imino carbons (H vs Me) do not affect the reaction outcome and afford Cp#Yb(DAD)2-(thf). The amido and alkoxo derivatives XYb(DAD)2-(dme) (X = N(SiMe3)2, tBuO) were obtained by the salt metathesis reactions of the in situ generated species [XYbCl2(thf)n] and Na2(thf)n[2,6-iPr2C6H3NC(Me)C(Me)NC6H3iPr2-2,6]. If the reaction was carried out in the presence of Li ions, it afforded an ate-complex {Li(thf)3}{Yb[2,6-iPr2C6H3NC(Me)C(Me)NC6H3iPr2-2,6]2-[N(SiMe3)2](μ-Cl)}. The X-ray studies of complexes XYbIII(DAD)2-(L) revealed that they feature the 2σ:η2-type of coordination of dianionic DAD ligands. Introduction of Me-substituents by the imino carbons of DADs leads to some elongation of Yb-Cp# bonds compared to the NCHCHN-analogues. The Yb-CNCCN bonds and the dihedral YbNN-NCCN angles were found to be the most sensitive to replacing H by Me. Unlike the formerly reported complex Cp?Yb[2,6-iPr2C6H3NCHCHNC6H3iPr2-2,6]2-(thf), the variable-temperature magnetic measurements (1.8-300 K) of complexes 3-5 and 7-9 did not reveal thermally induced redox isomeric transformations for these compounds. However, for complex (C5Me4H)Yb[2,6-iPr2C6H3NC(Me)C(Me)NC6H3iPr2-2,6](thf) at 9 K, the structural phase transition accompanied by changes of the coordination behavior of the DAD ligand was detected, which might hint for an onset of a temperature-induced redox isomerism. These results clearly indicate high sensitivity of redox isomeric transformations of XYbIII(DAD)2-L to the smallest changes of the structural and electronic properties of the DAD ligands. (Chemical Equation Presented).
- Shestakov, Boris G.,Mahrova, Tatyana V.,Larionova, Joulia,Long, Jêrome,Cherkasov, Anton V.,Fukin, Georgy K.,Lyssenko, Konstantin A.,Scherer, Wolfgang,Hauf, Christoph,Magdesieva, Tatiana V.,Levitskiy, Oleg A.,Trifonov, Alexander A.
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p. 1177 - 1185
(2015/04/27)
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- Synthesis and structures of ansa-titanocene complexes with diatomic bridging units for overall water splitting
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The synthesis of a series of ansa-titanocene dichlorides [Cp' 2TiCl2] (Cp′=bridged η5- tetramethylcyclopentadienyl) and the corresponding titanocene bis(trimethylsilyl)acetylene complexes [Cp′2Ti(η 2-Me3SiC2SiMe3)] is described. The ethanediyl-bridged complexes [C2H4(C5Me 4)2TiCl2] (2-Cl2) and [C 2H4(C5Me4)2Ti(η 2-Me3SiC2SiMe3)] (2-btmsa; btmsa=η2-Me3SiC2SiMe3) can be obtained from the hitherto unknown calcocenophane complex [C2H 4(C5Me4)2Ca(THF)2] (1). Furthermore, a heterodiatomic bridging unit containing both, a dimethylsilyl and a methylene group was introduced to yield the ansa-titanocene dichloride [Me2SiCH2(C5Me4) 2TiCl2] (3-Cl2) and the bis(trimethylsilyl) acetylene complex [Me2SiCH2(C5Me 4)2Ti(η2-Me3SiC 2SiMe3)] (3-btmsa). Besides, tetramethyldisilyl- and dimethylsilyl-bridged metallocene complexes (structural motif 4 and 5, respectively) were prepared. All ansa-titanocene alkyne complexes were reacted with stoichiometric amounts of water; the hydrolysis products were isolated as model complexes for the investigation of the elemental steps of overall water splitting. Compounds 1, 2-btmsa, 2-(OH)2, 3-Cl2, 3-btmsa, 4-(OH)2, 3-alkenyl and 5-alkenyl were characterised by X-ray diffraction analysis. Copyright
- Kessler, Monty,Hansen, Sven,Godemann, Christian,Spannenberg, Anke,Beweries, Torsten
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supporting information
p. 6350 - 6357
(2013/07/05)
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- 1,4-HYDROGENATION OF DIENES WITH RU COMPLEXES
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The present invention relates to the use of Ru complexes, having a cyclopentadienyl derivatives and a diene as ligands, together with some acidic additives for improving the selectivity in the 1,4-hydrogenation of conjugated dienes into the corresponding "cis "-alkene as major product, i.e. wherein the two substituents in position 2,3 of said diene are in a cis configuration in the corresponding alkene.
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Page/Page column 13
(2008/12/04)
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- Synthesis and electrochemical properties of slipped-cofacial porphyrin dimers of ferrocene-functionalized Zn-imidazolyl-porphyrins as potential terminal electron donors in photosynthetic models
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A systematic series of ferrocene-functionalized Zn-imidazolyl-porphyrins were synthesized to assemble into the slipped-cofacial porphyrin dimers through imidazolyl-to-zinc complementary coordination as artificial photosynthetic models. Direct substitution at the meso position of the porphyrin ring with ferrocence and octamethylferrocene leads to the characteristic electronic structures, while the ferrocene substituents through phenylene-ethenylene and phenylene-ethylene spacers mitigate the electronic communications. Bathochromic shift of Q band, fluorescence quenching, and redox potentials of porphyrin ring are rationalized by the degree of electron-donating ability of the terminal ferrocenes. the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006.
- Kalita, Dipak,Morisue, Mitsuhiko,Kobuke, Yoshiaki
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- Synthesis of Tetraalkylcyclopentadienes
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A method for synthesizing tetramethylcyclopentadiene from 2,3-dibromobutane is described. A 2-bromo-2-butene Grignard is reacted with an ethyl formate to produce a 3,5-dimethyl-2,5-heptadiene-4-ol magnesium bromide which is then quenched with acetic acid to produce 3,5-dimethyl-2,5-hepadiene-4-ol.
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Page column 4
(2008/06/13)
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- Process for the preparation of cyclopentadienyl metal salt and process for the preparation of derivative of cyclopentadiene using the same
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A cyclopentadienyl metal salt is prepared by reacting a cyclopentadiene and a metal hydride in the presence of an amine compound. Furthermore, a derivative of a cyclopentadiene in which a phenyl group is bonded to its cyclopentadienyl moiety through an element of the 14 group of the Periodic Table is prepared using such a reaction.
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- Chiral metallocenes: The synthesis and X-ray crystal structures of TiCl2(η5:η5-C5Me 4SiMe2C5H3R*) (R* = menthyl or neomenthyl) and related compounds
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The syntheses of the chiral ansa-metallocene complexes TiCl2(η5:η5-C5 Me4SiMe2C5H3R*) (R* = menthyl (4a) or neomenthyl (4b)) are reported; initially 4a was obtained as a 3:1 mixture of (R:S) diastereoisomers, which differ only in which face of the asymmetrically substituted cyclopentadienyl ring is bonded to the titanium (chiral descriptor shown). The major diastereomer 4aR was crystallized out optically pure from the initial reaction mixture, whereas the 4aS diastereoisomer was isolated after isomerizing a racemic mixture of 4a to a 1:3 mixture of (R:S) diastereoisomers using UV irradiation. The corresponding neomenthyl complex 4b was obtained as a 1.3:1 mixture of diastereoisomers that could not be separated. The optically pure 4aR was converted stereoselectively into the corresponding (R)-TiMe2(η5:η5-C5Me 4SiMe2C5H3R*) (R* = menthyl). Syntheses of the related indenyl ligand system C5Me4SiMe2C9H7 (3) is reported but complexation to titanium proved to be problematic although ZrCl2(η5:η5-C5Me 4SiMe2C9H6) (6) was isolated. The crystal structures of both 4aR and 4aS are reported and compared. Crystals of 4aR are orthorhombic, a = 27.857(11), b = 9.985(5), and c = 9.596(4) A, Z = 4, space group P212121 (D24, No. 19), and those of 4aS are monoclinic, a = 8.5810(10), b = 38.679(4), and c = 8.5842(10) A β = 113.001(2)°, Z = 4, space group P21 (C22, No. 4). The structures were solved by the Patterson method and 4aR was refined by blocked-cascade least-squares procedures to R = 0.0628 (Rω = 0.0503) for 902 reflections with |F|/σ(|F|) ≥ 3.0, whereas 4aS was refined by full-matrix least-squares procedures to R = 0.0646 (wR2 = 0.1829) for 5734 reflections with |F|/σ(|F|) ≥ 4.0. Both diastereomers of 4a catalyze hydrosilylation of ketones, but as expected from a comparison of the two crystal structures, the 4aR isomer is the more stereoselective catalyst, i.e., hydrosilylation of acetophenone followed by hydrolysis gives 82% enantiomeric excess (ee) of (S)-PhCH(Me)OH with 4aR whereas only 16% ee of (R)-PhCH(Me)OH with 4aS.
- Beagley,Davies,Adams,White
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p. 731 - 741
(2007/10/03)
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- Preparation of polyalkylated cyclopentadienes from isobornyl carboxylates
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A process for preparing tetraalkylated cyclopentadienes comprises (a) pyrolyzing an isobornyl carboxylate so as to form a mixture of 1,2,3- and 1,2,4-trimethylcyclopentadienes, (b) alkylating said mixture with an alkylating agent so as to form a mixture of alkyltrimethylcyclopentadiene isomers including 1,2,3,4-alkyltrimethylcyclopentadiene and, (c) thermally isomerizing the mixture of isomers obtained in step (b) so as to increase the proportion of 1,2,3,4-alkyltrimethylcyclopentadiene in said mixture of isomers.
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- Process of preparing cyclopentadiene and substituted derivatives thereof
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A process of preparing cyclopentadiene or substituted cyclopentadienes, such as tetramethylcyclopentadiene. The process involves contacting under reaction conditions cyclopentenol or a substituted cyclopentenol with a catalyst selected from (1) crystalline and amorphous aluminum phosphates, (2) aluminophosphate molecular sieves, and (3) silicoaluminophosphate molecular sieves. The process produces cyclopentadienes in high isolated yields.
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- Preparation of substituted cyclopentadienes
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A process is provided for preparing an substituted cyclopentadiene by the steps of (a) reacting a vinyl ketone with a vinyl organometallic compound to form a divinyl tertiary alcohol and (b) dehydrating/cyclizing the tertiary alcohol such as with an acid and/or heat to form the substituted cyclopentadiene.
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- Process for preparing cyclopentadienyl group-containing silicon compound or cyclopentadienyl group-containing germanium compound
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Disclosed is a process for preparing a cyclopentadienyl group-containing silicon compound or a cyclopentadienyl group-containing germanium compound, comprising reacting (i) a lithium, sodium or potassium salt of a cyclopentadiene derivative with (ii) a silicon halide compound or a germanium halide compound in the presence of a cyanide or a thiocyanate. The cyanide or the thiocyanate is preferably a copper salt. According to the process of the invention, a cyclopentadienyl group-containing silicon compound or a cyclopentadienyl group-containing germanium compound, which is very useful for the preparation of a metallocene complex catalyst component, can be prepared in a high yield for a short period of time.
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- Influence electronique et sterique du ligand tetramethylcyclopentadienyle sur les proprietes physiques et sur la reactivite de complexes du titane et du zirconium
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The complexes (C5Me4H)2MR1R2 (M=Ti, Zr) and (C5Me4H)(C5H5)MR1R2 (M=Ti) have been prepared (R1=R2=Cl, CH3, C6H5, p-C6H4CH3, CO; R1=Cl, R2=CH3, C6H5, p-C6H4CH3).The NMR and IR spectra of these complexes indicate that C5Me4H exhibits an electron-donor effect more important than C5H5 and a little bit weaker than that of C5Me5.A structural investigation of the complex (C5Me4H)2Zr(C6H5)Cl and the study of the 1H or 13C dynamic NMR properties of the compounds (C5Me4H)2MR1R2 (M=Ti, Zr; R1=R2=C6H5, p-C6H4CH3; R1=Cl, Br, R2=C6H5, p-C6H4CH3) show clearly that C5Me4H has a steric effect intermediate between C5H5 and C5Me5.The steric or electronic effects of C5Me4H have been used to induce specific isomerization reactions of various alkenes by using (C5Me4H)2Ti(CH3)2 as catalyst. --- Key words: zirconium, titanium, tetramethylcyclopentadienyl, photo-assisted, isomerization.
- Courtot, P.,Pichon, R.,Salaun, J. Y.,Toupet, L.
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p. 661 - 672
(2007/10/02)
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- New Heterodifunctional Ligands for Organotransition-Metal Chemistry: Ph2P(CH2)nC5Me4H (n=0, 2)
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The synthesis of two new heterodifunctional ligands for organotransition-metal chemistry, Ph2P(CH2)nC5Me4H (n=0, 2), is described.Both compounds are derived from the same intermediate, lithium tetramethylcyclopentadienide.For n=2 the ligand is obtained by a one-pot reaction including two successive nucleophilic substitutions.
- Szymoniak, Jan,Besancon, Jack,Dormond, Alain,Moise, Claude
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p. 1429 - 1432
(2007/10/02)
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- The Electron Spin Resonance Spectra of the Radical Cations of Furans, Thiophenes, and Pyrroles in Liquid Solution
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The radical cations of various furans, thiophenes, and pyrroles have been generated in fluid solution and characterised by e.s.r. spectroscopy.
- Davies, Alwyn G.,Julia, Luis,Yazdi, Safieh N.
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p. 929 - 930
(2007/10/02)
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- An Electron Spin Resonance Study of the Methylcyclopentadienyl Radicals, MenH5-nC5 (n=1-5)
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The radicals MenC5H5-n have been generated by photolysis of the corresponding hydrocarbons (n=3-5) or mercury derivatives (n=0-5) and their e.s.r. spectra have been recorded.The spectra are interpreted in terms of thermal population of the ψA and ψS molecular orbitals, for which the predicted hyperfine coupling constants are calculated by the McLachlan equation, taking λ 0.75 and Q(C5H5) -30 and Q(Me5C5) 31.85 G.The energy separations between the ψA and ψS MOs can be rationalised on the assumption that a methyl substituent on a carbon atom of the cyclopentadienyl carrying a unit ?-electron has a destablising interaction, within a factor of two, of 10 kJ mol-1.
- Davies, Alwyn G.,Lusztyk, Ewa,Lusztyk, Janusz
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p. 729 - 736
(2007/10/02)
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- NMR Spectroscopy on Paramagnetic Complexes, XXVII. Paramagnetic 1,1',2,2',3,3',4,4'-Octamethylmetallocenes
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The tetramethylated cyclopentadienyl anion has been prepared from tiglinic acid and reacted with solvated metal(II) chlorides to give new octamethylmetallocenes (Me4cp)2M.For M = V, Cr, Co and Ni the paramagnetic 1H and 13C spectra have been recorded.The NMR data prove the molecular structure and show that all methyl groups rotate almost freely.The methyl proton resonance of the nickelocene may serve as a probe for the adjustment of metallocene properties by ring substitution.Based on qualitative MO arguments the correlation of electron spin densities and paramagnetic shifts lead to an understanding of the signal splitting of cobaltocenes.From the electronic point of view the octamethylmetallocenes may be regarded as being invers to 1,1'-dimethylmetallocenes. - Key words: Octamethylmetallocenes, Paramagnetic 1H/13C NMR
- Koehler, Frank H.,Doll, Karl H.
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p. 144 - 150
(2007/10/02)
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