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Closed Access item Structural Analysis of Zincocenes with Substituted Cyclopentadienyl Rings

Authors:Fernández, Rafael
Grirrane, Abdessamad
Resa, I.
Rodríguez, Amor
Carmona Guzmán, Ernesto
Álvarez, Eleuterio
Gutiérrez-Puebla, Enrique
Monge, M. Angeles
López del Amo, Juan Miguel
Limbach, Hans-Heinrich
Lledós, Agustí
Maseras, Feliu
Río, Diego del
Keywords:Density functional calculations, Iminoacyl, Metallocenes, Structure elucidation, Zinc
Issue Date:9-Nov-2008
Citation:Chemistry - a European Journal 15(4): 924-935 (2009)
Abstract:New zincocenes [ZnCp′2] (2–5) with substituted cyclopentadienyl ligands C5Me4H, C5Me4tBu, C5Me4SiMe2tBu and C5Me4SiMe3, respectively, have been prepared by the reaction of ZnCl2 with the appropriate Cp′-transfer reagent. For a comparative structural study, the known [Zn(C5H4SiMe3)2] (1), has also been investigated, along with the mixed-ring zincocenes [Zn(C5Me5)(C5Me4SiMe3)] (6) and [Zn(C5Me5)(C5H4SiMe3)] (7), the last two obtained by conproportionation of [Zn(C5Me5)2] with 5 or 1, as appropriate. All new compounds were characterised by NMR spectroscopy, and by X-ray methods, with the exception of 7, which yields a side-product (C) upon attempted crystallisation. Compounds 5 and 6 were also investigated by 13C CPMAS NMR spectroscopy. Zincocenes 1 and 2 have infinite chain structures with bridging Cp′ ligands, while 3 and 4 exhibit slipped-sandwich geometries. Compounds 5 and 6 have rigid, η5/η1(σ) structures, in which the monohapto C5Me4SiMe3 ligand is bound to zinc through the silyl-bearing carbon atom, forming a Zn-C bond of comparable strength to the Zn-Me bond in ZnMe2. Zincocene 5 has dynamic behaviour in solution, but a rigid η5/η1(σ) structure in the solid state, as revealed by 13C CPMAS NMR studies, whereas for 6 the different nature of the Cp′ ligands and of the ring substituents of the η1-Cp′ group (Me and SiMe3) have permitted observation for the first time of the rigid η5/η1 solution structure. Iminoacyl compounds of composition [Zn(η5-C5Me4R)(η1-C(NXyl)C5Me4R)] resulting from the reactions of some of the above zincocenes and CNXyl (Xyl=2,6-dimethylphenylisocyanide) have also been obtained and characterised.
Description:12 páginas, 6 figuras, 3 tablas, 2 esquemas
Publisher version (URL):http://dx.doi.org/10.1002/chem.200801917
E-ISSNmetadata.dc.identifier.doi = DOI:1521-3765
Appears in Collections:(IIQ) Artículos
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