The Cp*Si(+) cation acts as a stoichiometric source of silicon in the reaction with the disilenide Tip(2)Si=Si(Tip)Li (Tip = 2,4,6-(i)Pr(3)C(6)H(2)) affording known neutral unsaturated silicon clusters. It thereby provides a conceptually different approach to this novel class of compounds. The proposed mechanism involves a Cp*-substituted cyclotrisilene in which Cp*(-) acts as a leaving group upon single electron reduction or in a nucleophilic substitution step.
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http://dx.doi.org/10.1039/c2cc33911k | DOI Listing |
Dalton Trans
June 2023
Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K.
We report the synthesis and characterisation of a series of M(IV) substituted cyclopentadienyl hypersilanide complexes of the general formula [M(Cp){Si(SiMe)}(X)] (M = Hf, Th; Cp = Cp', {CH(SiMe)} or Cp'', {CH(SiMe)-1,3}; X = Cl, CH). The separate salt metathesis reactions of [M(Cp)(Cl)] (M = Zr or Hf, Cp = Cp'; M = Hf or Th, Cp = Cp'') with equimolar K{Si(SiMe)} gave the respective mono-silanide complexes [M(Cp'){Si(SiMe)}(Cl)] (M = Zr, 1; Hf, 2), [Hf(Cp'')(Cp'){Si(SiMe)}(Cl)] (3) and [Th(Cp''){Si(SiMe)}(Cl)] (4), with only a trace amount of 3 presumably formed silatropic and sigmatropic shifts; the synthesis of 1 from [Zr(Cp')(Cl)] and Li{Si(SiMe)} has been reported previously. The salt elimination reaction of 2 with one equivalent of allylmagnesium chloride gave [Hf(Cp'){Si(SiMe)}(η-CH)] (5), whilst the corresponding reaction of 2 with equimolar benzyl potassium yielded [Hf(Cp')(CHPh)] (6) together with a mixture of other products, with elimination of both KCl and K{Si(SiMe)}.
View Article and Find Full Text PDFJ Am Chem Soc
December 2020
Institut für Anorganische Chemie, Georg-August Universität Göttingen, Tammannstraße 4, 37077 Göttingen, Germany.
Metathesis reaction of a dilithio borole dianion, a cyclic π-ligand isoelectronic to ubiquitous cyclopentadienyls, with two equivalents of "silicocenium" cation [Cp*Si] as a source of low-valent Si(II), cleanly gives a borole half-sandwich π-complex of Si(II) and silicocene. The resulting half-sandwich complex is a neutral isoelectronic analogue to the iconic silicocenium cation and features the rare structural motif of an apical silicon(II) atom with an energetically high lying lone pair of electrons that is shown to be accessible for coordination chemistry toward tungsten carbonyl. Protonation at the Si(II) atom with [H(OEt)][Al{OC(CF)}] induces formal oxidation, and the compound rearranges to incorporate the Si atom into the carbocyclic base to give an unprecedented cationic 5-sila-6-borabicyclo[2.
View Article and Find Full Text PDFChemistry
July 2014
Faculty of Chemistry, University of Bielefeld, 33615 Bielefeld (Germany).
In the flourishing chemistry of divalent silicon, π-complex formation between silicon and the pentamethylcyclopentadienyl (Cp*) group is one of the successful strategies for thermodynamic and/or kinetic stabilization. Here, the diverse reactivity of the [Cp*Si](+) ion is described. Its chemistry is characterized by the addition of anionic and neutral nucleophiles and by the easy hapticity change and the leaving-group character of the Cp* group.
View Article and Find Full Text PDFChem Commun (Camb)
August 2012
Faculty of Chemistry, University of Bielefeld, 33613 Bielefeld, Germany.
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