A new mechanistic path in the reaction of ruthenium trichloride with silylated cyclopentadienes. Ionic transition metal halides as desilylating agents
01 Jan 1991-Journal of The Chemical Society, Chemical Communications (The Royal Society of Chemistry)-Iss: 15, pp 1026-1027
TL;DR: The reaction of hydrated ruthenium trichloride with mono-, bis-and tris-(trimethylsilyl)cyclopentadiene in alcohol solvents leads to high yields of ruthensocene.
Abstract: The reaction of hydrated ruthenium trichloride with mono-, bis- and tris-(trimethylsilyl)cyclopentadiene in alcohol solvents leads to high yields of ruthenocene; these processes proceed through an unprecedented chloride ion-induced desilylation of the silylated Cyclopentadienes followed by reaction of RuIII ion with cyclopentadiene, rather than the mechanistically distinct carbon–silicon bond cleavage that has been observed in other transition metal halide systems.
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TL;DR: The reaction between Ru(Me3tacn)Cl3 and trifluoromethanesulfonate in ethanol has been studied in this paper, showing that the η5-bonded unsaturated hydrocarbon moiety is virtually planar.
19 citations
TL;DR: A series of cis-alkynyl(silyl)platinum(II) complexes was prepared via the chemoselective C(sp)−Si bond cleavage of alkynyl-silanes by a platinum(0) complex ligated with the P-N hemilabile bidentate ligand as discussed by the authors.
12 citations
TL;DR: In this paper, the formation of sPP fractions from the a priori isoselective 1b and 2b systems is attributed to a desilylation side reaction, which takes place in the precatalyst synthesis step and possibly also during the polymerization, resulting in the generation of the Me3Si-free catalytically active species.
Abstract: Single isoselective C1-symmetric {Ph2C-(Flu)(3-Me3Si-Cp)}ZrR2 (R = Cl (1b), Me (2b)) metallocene precatalysts, upon activation with MAO or [PhNMe2H]+[B(C6F5)4]−/iBu3Al, produce isotactic polypropylene (PP) (up to 80% mmmm), which is more enriched with syndiotactic pentads (0.9–2.2% rrrr) than the statistical model assumes. Similar or even more syndiotactically enriched PPs (3.0–25.4% rrrr) are obtained using combinations of 1b or 2b with Cs-symmetric syndioselective {Ph2C-(Flu)(Cp)}ZrR2 (R = Cl (1a), Me (2a)) metallocenes. While NMR spectroscopy, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC) analyses do not provide explicit evidence on the nature of these polymers, temperature rising elution fractionation (TREF) unambiguously identifies them as blends of iPP and sPP polymers and not discrete iPP−b−sPP stereoblock copolymers. The formation of sPP fractions from the a priori isoselective 1b and 2b systems is attributed to a desilylation side reaction, which takes place in the precatalyst synthesis step and possibly also during the polymerization, resulting in the generation of the Me3Si-free syndioselective catalytically active species. Activation of 2a with B(C6F5)3 and [PhNMe2H]+[B(C6F5)4]− selectively leads to the corresponding cationic complexes 3a and 4a, as confirmed by NMR spectroscopic methods and the solid-state structure of {Ph2C-(Flu)(Cp)}ZrMe(μ-Me)B(C6F5)3 (3a). On the other hand, the activation of 2b with the same molecular activators is less selective, and the formation of the corresponding cationic products 3b and 4b along with unidentified impurities is monitored by NMR spectroscopy. A possible chain-shuttling process between isoselective and syndioselective active species, mediated by Me3Al or iBu3Al, appears to be inoperative under given conditions.
4 citations
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171 citations
TL;DR: The reaction between (C5Me5)SiMe3 and group 4 element tetrahalides MX4 (M Ti, Cl, Br, I, Zr, Hf, X ǫ, Cl) gives the corresponding (η5-C5me5)MX3 derivatives in nearly quantitative yields in one-step procedure without the need for further purification as discussed by the authors.
165 citations
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TL;DR: In this article, a number of silylated cyclopentadienes with zirconium and hafnium tetrachlorides have been examined, and the exclusive product is the (1,3-bis(trimethylsilyl) cyclopenadienyl) metal trichloride.
68 citations