Well‐Defined Single‐Site Monohydride Silica‐Supported Zirconium from Azazirconacyclopropane

Hamzaoui, Bilel; Eter, Mohamad El; Abou-Hamad, Edy; Yin, Chuancun; Pelletier, Jérémie D. A.; Basset, Jean‐Marie

doi:10.1002/chem.201405788

Cited by 17 publications

(30 citation statements)

References 44 publications

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“…The nature of the M–X bond is also important to their reactivity; for example, selective substitution of these groups with ancillary ligands (LX) provides routes to reactive complexes, including catalysts. While the rich chemistry of surface-supported organometallic compounds indicates that alkyl species are desirable, work with grafted early-metal amides suggests their emerging potential in catalysis. − In rare-earth chemistry, homoleptic organometallic and pseudo-organometallic compounds are particularly important starting materials, but their large ionic radii and low numbers of X-type ligands (either two or three) add to the challenge of preparing reactive monometallic species …”

Section: Introductionmentioning

confidence: 99%

β-SiH-Containing Tris(silazido) Rare-Earth Complexes as Homogeneous and Grafted Single-Site Catalyst Precursors for Hydroamination

et al. 2017

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A series of homoleptic rare-earth silazido compounds and their silica-grafted derivatives were prepared to compare spectroscopic and catalytic features under homogeneous and interfacial conditions. Trivalent tris-(silazido) compounds Ln{N(SiHMe 2 )tBu} 3 (Ln = Sc (1), Y (2), Lu (3)) are prepared in high yield by salt metathesis reactions. Solution-phase and solid-state characterization of 1− 3 by NMR and IR spectroscopy and X-ray diffraction reveals Ln↼H−Si interactions. These features are retained in solventcoordinated 2·Et 2 O, 2·THF, and 3·THF. The change in spectroscopic features characterizing the secondary interactions (ν SiH , 1 J SiH ) from the unactivated SiH in the silazane HN(SiHMe 2 )tBu follows the trend 3 > 2 > 1 ≈ 2·Et 2 O > 2·THF ≈ 3· THF. Ligand lability follows the same pattern, with Et 2 O readily dissociating from 2·Et 2 O while THF is displaced only during surface grafting reactions. 1 and 2·THF graft onto mesoporous silica nanoparticles (MSN) to give Ln{N(SiHMe 2 )tBu} n @MSN (Ln = Sc (1@MSN), Y (2@MSN)) along with THF and protonated silazido as HN(SiHMe 2 )tBu and H 2 NtBu. The surface species are characterized by multinuclear and multidimensional solid-state (SS) NMR spectroscopic techniques, as well as diffuse reflectance FTIR, elemental analysis, and reaction stoichiometry. A key 1 J SiH SSNMR measurement reveals that the grafted sites most closely resemble Ln·THF adducts, suggesting that siloxane coordination occurs in grafted compounds. These species catalyze the hydroamination/bicyclization of aminodialkenes, and both solution-phase and interfacial conditions provide the bicyclized product with equivalent cis:trans ratios. Similar diastereoselectivities mediated by catalytic sites under the two conditions suggest similar effective environments.

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Section: Introductionmentioning

confidence: 99%

β-SiH-Containing Tris(silazido) Rare-Earth Complexes as Homogeneous and Grafted Single-Site Catalyst Precursors for Hydroamination

et al. 2017

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“…[9][10][11][12][13][14] One of the simplest ways to make such models compounds is to react the surface silanols (^Si-OH) of partially dehydroxylated silica with a metal-alkyl to obtain in principle well dened graed complexes. 2,9,15,16 However, it appeared progressively that depending on the degree of dehydroxylation of a support, mono, bi and multipodal species can be generated. 2,9,[17][18][19] In fact there is growing evidence that the graed complexes interact with the surrounding atoms present on the surface (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Well-defined silica supported aluminum hydride: another step towards the utopian single site dream?

et al. 2015

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“…22,23 To date, heterogeneous catalysts for imine metathesis have not been reported. Our recent foray into silica supported zirconium amido catalysts 24,25 encouraged us to examine the formation and the reactivity of the related metal imido complexes. Note that MQN fragments supported on silica have been documented only as spectator ligands for olefin metathesis molybdenum catalysts.…”

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confidence: 99%

Well-defined silica-supported zirconium–imido complexes mediated heterogeneous imine metathesis

et al. 2016

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Upon prolonged thermal exposure under vacuum, a well-defined single-site surface species [([triple bond, length as m-dash]Si-O-)Zr(NEt2)3] () evolves into an ethylimido complex [([triple bond, length as m-dash]Si-O-)Zr([double bond, length as m-dash]NEt)NEt2] (). Reactions of with an imine substrate result in imido/imine ([double bond, length as m-dash]NRi, R: Et, Ph) exchange (metathesis) with the formation of [([triple bond, length as m-dash]Si-O-)Zr([double bond, length as m-dash]NPh)NEt2] (). Compounds and effectively catalyze imine/imine cross-metathesis and are thus considered as the first heterogeneous catalysts active for imine metathesis.

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Well‐Defined Single‐Site Monohydride Silica‐Supported Zirconium from Azazirconacyclopropane

Cited by 17 publications

References 44 publications

β-SiH-Containing Tris(silazido) Rare-Earth Complexes as Homogeneous and Grafted Single-Site Catalyst Precursors for Hydroamination

β-SiH-Containing Tris(silazido) Rare-Earth Complexes as Homogeneous and Grafted Single-Site Catalyst Precursors for Hydroamination

Well-defined silica supported aluminum hydride: another step towards the utopian single site dream?

Well-defined silica-supported zirconium–imido complexes mediated heterogeneous imine metathesis

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