Chemistry. 2015 Feb 16;21(8):3242-8. doi: 10.1002/chem.201406219. Epub 2015 Jan 12.

Reactions of group 4 metallocenes with monosubstituted acetonitriles: keteniminate formation versus C-C coupling.

Chemistry (Weinheim an der Bergstrasse, Germany)

Lisanne Becker, Martin Haehnel, Anke Spannenberg, Perdita Arndt, Uwe Rosenthal

PMID: 25641093 DOI: 10.1002/chem.201406219

Abstract

The reactions of the Group 4 metallocene dichlorides [Cp'2 MCl2 ] (1 a: M=Ti, Cp'=Cp*=η(5) -pentamethylcyclopentadienyl, 1 b: M=Zr, Cp'=Cp=η(5) -cyclopentadienyl) with lithiated MesCH2-C≡N gave [Cp*2 TiCl(N=C=C(HMes))] (3; Mes=mesityl) in the case of 1 a. For compound 1 b, a nitrile-nitrile coupling resulted in a five-membered bridge in 4. The reaction of the metallocene alkyne complex [Cp*2 Zr(η(2) -Me3 SiC2 SiMe3 )] (2) with PhCH2 C≡N led in the first step to the unstable product [Cp*2 Zr(η(2) -Me3 SiC2 SiMe3 )(NC=CH2 Ph)] (5). After the elimination of the alkyne, a mixture of products was formed. By variation of the solvent and the reaction temperature, three compounds were isolated: a diazadiene complex 6, a bis(keteniminate) complex 7, and 8 with a keteniminate ligand and a five-membered metallacycle. Subsequent variation of the Cp ligand and the metal center by using [Cp2 Zr] and [Cp*2 Ti] with Me3 SiC2 SiMe3 in the reactions with PhCH2-C≡N gave complex mixtures.

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Keywords: CC coupling; H shift; deprotonation; metallacycles; metallocenes

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