Cyclopentadienyl-Silyl-Amido versus Imido Niobium Complexes. The Role of Additional Amine Functionalities: A Combined Experimental and Theoretical Study

Maestre, M. Carmen; Mosquera, Marta E. G.; Jacobsen, Heiko; Jiménez, Gerardo; Cuenca, Tomás

doi:10.1021/om701003t

Cited by 13 publications

(32 citation statements)

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“…protic reagents such as water, 29,30 alcohols, 31-33 silanols, 34 primary monoamines, [35][36][37] and diamines. [38][39][40][41][42] We are interested in understanding the pathway following these reactions since it would enable us to attain greater control over such processes. With this idea in mind, we initially studied the behavior that [Nb(η 5 -C 5 H 4 SiMe 2 -Cl)Cl 4 ] features in its reactions with primary mono-and diamines.…”

Section: Received September 14 2009mentioning

confidence: 99%

M−Cl/Si−Cl Preferential Reactivity in Chlorosilyl-Substituted Cyclopentadienyl Early Transition Metal Complexes in Reactions with Amines: Key to Understanding the Nature of the Final Product

Paniagua

Mosquera

Jacobsen³

et al. 2009

Organometallics

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The reaction of [Ti(η 5 -C 5 Me 4 SiMe 2 Cl)Cl 3 ] (1) with 1 equiv of different ethylenediamines, NHR-(CH 2 ) 2 NR 0 R 00 , regiospecifically affords cyclopentadienyl-silyl-amido derivatives with constrainedgeometry, [Ti{η 5 -C 5 Me 4 SiMe 2 -κ-N(CH 2 ) 2 NR 0 R 00 }Cl 2 ] (R 0 =R 00 =H, 2a; R 0 =H, R 00 =Me, 2b; R 0 = R 00 =Me, 2c) or unstrained structure, [Ti{η 5 -C 5 Me 4 SiMe 2 NMe(CH 2 ) 2 -κ-NMe}Cl 2 ] (3). Treatment of 1 with 1.5 equiv of ethylenediamine gives a mixture of 2a and the transient complex [Ti{η 5 -C 5 Me 4 SiMe 2 NH(CH 2 ) 2 NH 2 }Cl 3 ] (4), which is transformed into 2a upon addition of a base. The reaction of 1 with N,N,N 0 -trimethylethylenediamine permits the synthesis and isolation of the complex [Ti{η 5 -C 5 Me 4 SiMe 2 NMe(CH 2 ) 2 NMe 2 }Cl 3 ] (5). Compound 1 reacts with 0.5 equiv of NH 2 (CH 2 ) 2 NH 2 to yield a mixture of 2a along with the tethered dinuclear cyclopentadienyl-silyl-amido compound [Ti{η 5 -C 5 Me 4 SiMe 2 -κ-N(CH 2 )-}Cl 2 ] 2 (6).Currently, there is a continuous and increasing interest in the chemistry of transition metal compounds bearing ancillary polydentate ligands. 1-5 Modification of the ligand environment at the metal centers has enabled the preparation of new generations of polymerization catalyst precursors with excellent performance. 6-14 Among the multidentate ligands most widely studied, a prominent class consists of bifunctional cyclopentadienyl ligands incorporating neutral or anionic appended donor substituents. [15][16][17][18] The relevance of this research area is inferred from the numerous reviews of derivatives of this type recently published. 1,3,16,17 This field has largely been stimulated by the remarkable success of the group 4 metal "constrained-geometry" complexes as alternative catalysts to the classical bis-(cyclopentadienyl) systems 19-22 (MCp 2 X 2 ) for R-olefin polymerization processes. 23,24 One of our ongoing research lines is focused on the development of a new, efficient, and versatile alternative strategy to prepare transition metal complexes containing a bifunctional cyclopentadienyl ligand, 25 based on protonolysis reactions of M-Cl and Si-Cl bonds from chlorosilylsubstituted cyclopentadienyl compounds, 26-28 in reactions with ‡Correspondence concerning the crystallography data should be addressed to this author.

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Section: Received September 14 2009mentioning

confidence: 99%

M−Cl/Si−Cl Preferential Reactivity in Chlorosilyl-Substituted Cyclopentadienyl Early Transition Metal Complexes in Reactions with Amines: Key to Understanding the Nature of the Final Product

Paniagua

Mosquera

Jacobsen³

et al. 2009

Organometallics

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“…Similar behaviour has been observed for analogous cyclopentadienyl titanium derivatives. [26][27][28] Such altered behaviour is due to the different trans influence derived from the presence of a chloride or a cyclopentadienyl ligand located in the trans position with respect to the amino functionality in 6a-1 and 6a-2, respectively.…”

Section: Introductionmentioning

confidence: 99%

Monocyclopentadienyl Phenoxido–Amino and Phenoxido–Amido Titanium Complexes: Synthesis, Characterisation, and Reactivity of Asymmetric Metal Centre Derivatives

et al. 2008

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Reduction of phenol-imine derivatives RЈN=CH(3,5-R 2 C 6 H 2 -2-OH) (R = tBu; RЈ = C 6 H 5 1a, p-MeC 6 H 4 1b, Cy 1c, tBu 1d, 2,6-Me 2 C 6 H 3 1e; R = H; RЈ = p-MeC 6 H 4 1f; Cy = cyclohexyl) with MBH 4 (M = Li, Na) or AlLiH 4 in ethyl ether or thf at room temperature affords the phenol-amine compounds RЈNHCH 2 (3,5-R 2 C 6 H 2 -2-OH) 2a-c and 2e,f. The N-R- [2,4-ditert-butyl]benzo-1-oxa-3-azine species (R = tBu 2d1, 2,6-Me 2 C 6 H 3 2e1) are obtained by Mannich reaction of 2,4-ditert-butylphenol with RNH 2 in refluxing methanol. Intermediate 2d1 is converted in ethanol at room temperature into N-tert-butyl [2-hydroxy-3,5-di-tert-butyl]benzylamine (2d), whereas 2e is not obtained from 2e1 by using this procedure. N-alkyl,N-tert-butyl[2-hydroxy-3,5-di-tert-butyl]benzylamine compounds tBuN(R)CH

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“…The resulting suspension was filtered and the solvent was completely removed from the yellow solution under vacuum to give an orange oil, which was identified as a mixture of cis-10 and trans-10 in a molar ratio of approximately 1:1; yield 0.18 g (0.43 mmol, 53 %). C 16 . Stirring the reaction mixture at room temperature overnight gave an orange suspension.…”

Section: H 4 [Sime 2 (Ch=chch 3 )](Sime 3 ) (Cis+trans-2)mentioning

confidence: 99%

“…Heating solutions of the mixture in THF permitted the major isomer trans-11 to be isolated and allowed the assignment of NMR spectroscopic signals for each of the cis and trans isomers; yield 0.30 g (0.59 mmol, 60 %). C 16 …”

Section: H 4 [Sime 2 (Ch=chch 3 )](Sime 3 ) (Cis+trans-2)mentioning

confidence: 99%

“…[10] We have a longstanding interest in silyl-substituted cyclopentadienyl metal compounds. Synthesis of ansa-dicyclopentadienyl [11] and early transition-metal (amidosilyl)cyclopentadienyl compounds, [5,6,[12][13][14][15] comparative studies on the chemical behaviour of Si-Cl and M-Cl (M = group 4 and 5 metals) bonds versus different organic reagents [13,16] and studies on polynuclear systems with Si-O-M [12,17,18] bonds are among our research topics.…”

Section: Introductionmentioning

confidence: 99%

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Mixed Disilyl‐Substituted Cyclopentadiene Derivatives and Corresponding Zirconium, Molybdenum and Tungsten Compounds

et al. 2010

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Cyclopentadienyl-Silyl-Amido versus Imido Niobium Complexes. The Role of Additional Amine Functionalities: A Combined Experimental and Theoretical Study

Cited by 13 publications

References 50 publications

M−Cl/Si−Cl Preferential Reactivity in Chlorosilyl-Substituted Cyclopentadienyl Early Transition Metal Complexes in Reactions with Amines: Key to Understanding the Nature of the Final Product

M−Cl/Si−Cl Preferential Reactivity in Chlorosilyl-Substituted Cyclopentadienyl Early Transition Metal Complexes in Reactions with Amines: Key to Understanding the Nature of the Final Product

Monocyclopentadienyl Phenoxido–Amino and Phenoxido–Amido Titanium Complexes: Synthesis, Characterisation, and Reactivity of Asymmetric Metal Centre Derivatives

Mixed Disilyl‐Substituted Cyclopentadiene Derivatives and Corresponding Zirconium, Molybdenum and Tungsten Compounds

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