18053-75-3Relevant academic research and scientific papers
From Carbanions to Organometallic Compounds: Quantification of Metal Ion Effects on Nucleophilic Reactivities
Corral-Bautista, Francisco,Klier, Lydia,Knochel, Paul,Mayr, Herbert
, p. 12497 - 12500 (2015)
The influence of the metal on the nucleophilic reactivities of indenyl metal compounds was quantitatively determined by kinetic investigations of their reactions with benzhydrylium ions (Ar2CH+) and structurally related quinone methides. With the correlation equation logk2=sN(N+E), it can be derived that the ionic indenyl alkali compounds are 1018 to 1024 times more reactive (depending on the reference electrophile) than the corresponding indenyltrimethylsilane. Different worlds: Kinetic investigations with reference electrophiles show that a reaction with an electrophile, which would proceed within milliseconds with indenyl lithium, would require much more than the age of the universe with the corresponding organosilicon compound. Met=metal.
3,4-, 4,7- and 1,4,7-Substituted indenyl-TiCl3 complexes: Synthesis and comparison of substituent effects
Wei?, Thomas,Meichel, Eduard,Sachse, Helga,Spange, Stefan,Lang, Heinrich
, p. 1083 - 1094 (2008/10/09)
Me3Si-substituted indenes of type 1-SiMe3-3,4- (CH2)3C9H5 (9), 1-SiMe 3-4-R-7-R′C9H5 (11a, R = R′ = Me; 11b, R = R′ = Ph; 11c, R = Me, R′ = Ph) and 1,1′-(SiMe 3)2-4,7-Me2C9H4 (12) were synthesised as precursors for piano-stool type halfsandwich indenyl-titanium trichloride complexes. Treatment of 9, 11, and 12 with equimolar amounts of TiCU gives the complexes (η5-3,4-(CH2)3C 9H5)TiCl3 (13), (η5-4-R-7- R′C9H5)TiCl3 (14a, R = R′ = Me; 14b, R = R′ = Ph; 14c, R = Me, R′ = Ph), and (η5-1- SiMe3-4,7-Me2C9H4)TiCl3 (15), respectively, with liberation of Me3SiCl. Detailed UV/vis spectroscopic and cyclic voltammetric studies were carried out which allow a comparison of substituent effects in 13-15.
Influence of the para-substitution in bis(arylimino)pyridine iron complexes on the catalytic oligomerization and polymerization of ethylene
G?rl, Christian,Alt, Helmut G.
, p. 4580 - 4592 (2008/02/13)
A series of nine bis(arylimino)pyridine iron complexes containing halogen or alkynyl substituents in their ligand frameworks was synthesized and characterized. After activation with methylalumoxane (MAO), these catalysts oligomerize or polymerize ethylene to give highly linear products. The introduction of halogen or alkynyl substituents in the para-position of the iminophenyl rings has a great influence on the polymerization activities of the corresponding iron complexes.
Synthesis, structure, and ethene polymerisation catalysis of 1- or 2-silyl substituted bis[indenyl]zirconium(IV) dichlorides
Moeller, Andreas C.,Heyn, Richard H.,Blom, Richard,Swang, Ole,Goerbitz, Carl Henrik,Kopf, Juergen
, p. 1578 - 1589 (2007/10/03)
The systematic syntheses of 1- and 2-substituted silylindenes, with a wide variety of substitution patterns on the silyl moiety, and their corresponding zirconocene dichlorides are presented. The rac- and meso-diastereomers of the 1-substituted zirconocene dichlorides can in most cases be separated. Instable zirconocenes were observed for certain substitution patterns. Two of the obtained zirconocene dichlorides, bis[2-(dimethylsilyl)indenyl]zirconium dichloride (4a) and bis[2-(trimethylsilyl)indenyl]zirconium dichloride (4b), were characterised by single crystal X-ray diffraction. On the basis of DFT results, the two compounds are geometrically similar, i.e. the additional methyl group on the silyl moiety only affects the conformational energy profile. Differences in their catalyst performance in the homopolymerisation studies with ethane are thus attributed to conformational control. For the remaining complexes, sterically less demanding silyl groups seem to be favoured with respect to the catalyst performance. All the 2-isomers have lower polymerisation activities than the unsubstituted bis[indenyl]zirconium dichloride/MAO system. Curiously, the rac-bis[1-(dimethylphenylsilyl)indenyl]zirconium dichloride/MAO system is found to be the most active catalyst in ethene homopolymerisations.
Zirconium bis-indenyl compounds. Synthesis and X-ray crystallography study of 1- and 2-substituted bis(R-indenyl)zirconium dichloride metallocenes
Grimmer, Neil E.,Coville, Neil J.,De Koning, Charles B.,Smith, Jeremy M.,Cook, Leanne M.
, p. 112 - 127 (2007/10/03)
A series of 1- and 2-substituted indenyl ligands were prepared and used in the synthesis of [1-R-Ind]2ZrCl2 [R = Me (2b), Et (4b), iPr (5b), tBu (6b), SiMe3 (8b), Ph (10b), Bz (12b), 1-Naph (14b)] and [2-R-Ind]2ZrCl2 [R = Me (1b), Et (3b), SiMe3 (7b), Ph (9b), Bz (11b), 1-Naph (13b)] metallocenes. An X-ray crystallographic study of 4b and 10b showed the complexes to be the racemic diastereomers (4b, both the R,R and S,S-enantiomers and 10b, the S,S-enantiomer). The X-ray data together with NMR spectral data revealed that the size of the substituent influenced the orientation the two indenyl ligands of the metallocenes. The 4b diastereomers are both found to crystallize with their ethyl groups syn (bis-central) with respect to each other whereas the larger phenyl groups in 10b results in an anti (bis-lateral) orientation of the indenyl ligands.
Process for preparing cyclopentadienyl group-containing silicon compound or cyclopentadienyl group-containing germanium compound
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, (2008/06/13)
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.
Regioselectivity of Radical-induced Bond Cleavages in Epoxides
Murphy, John A.,Patterson, Christopher W.
, p. 405 - 410 (2007/10/02)
Radical-induced carbon-carbon and carbon-oxygen bond cleavage reactions in a highly substituted epoxide, and in epoxides fused to other rings are reported.Substitution at the site of the developing radical assists C-C bond cleavage.In ring-fused epoxides, C-C bond cleavage was not seen where stereoelectronic factors oppose it.
Synthesis and reaction chemistry of (η5-indenyl)(cyclooctadiene)iridium: Migration of indenyl from iridium to cyclooctadiene
Merola, Joseph S.,Kacmarcik, Raymond T.
, p. 778 - 784 (2008/10/08)
(η5-Indenyl)(cyclooctadiene)iridium was synthesized in high yield from chloro(cyclooctadiene)iridium dimer and lithium indenide. The reaction chemistry of the above compound was investigated with respect to the displacement of the cyclooctadiene with various nucleophiles. Thus, (η5-indenyl)dicarbonyliridium could be synthesized in high yield by treating the cyclooctadiene complex with carbon monoxide at atmospheric pressure. However, the addition of trimethylphosphine, PMe3, to the cyclooctadiene complex resulted not in the displacement of cyclooctadiene but in the migration of indene from iridium to cyclooctadiene forming (2-indenylcyclooct-5-en-1-yl)tris(trimethylphosphine)iridium, I, quantitatively. A single-crystal X-ray structural determination of I was carried out and confirmed the migration of indene to the cyclooctadiene. I crystallizes in the orthorhombic space group P212121 with a = 10.019 (1) A?, b = 18.836 (3) A?, c = 29.602 (4) A?, V = 5586 (2) A?3, and Z = 8. The syntheses of a related series of (trimethylsilyl-substituted indenyl)iridium complexes are also reported along with some suggestions for the mechanism of the iridium to cyclooctadiene indenyl migration.
Synthesis of α,β-unsaturated sulfines from silylindenes and sulfur dioxide
Porskamp, P. A. T. W.,Wijdeven, A. M. van de,Zwanenburg, B.
, p. 506 - 510 (2007/10/02)
The synthesis of a variety of substituted indenethione S-oxide (all α,β-unsaturated sulfines) is described.Essentially these sulfines are prepared by the reaction of α-silyl carbanions with an excess of sulfur dioxide (modified Peterson reaction).The requisite α-silyl carbanions are generated by two different routes, i.e. by α-deprotonation of trimethylsilyl-substituted indenes and by nucleophilic δ-addition of alkyllithium compounds to dienesilanes.In all cases, the sulfines prepared were converted into cycloadducts by reaction with 2,3-dimethyl-1,3-butadiene.
