Organometallic compounds of Group 13 elements containing the ligand C(SiMe3)2(SiMe2C5H4N-2)

Howson, James; Eaborn, Colin; Hitchcock, Peter B.; Hill, Michael S.; Smith, J. David

doi:10.1016/j.jorganchem.2004.08.029

Cited by 12 publications

(13 citation statements)

References 58 publications

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“…We have chosen the bulky Pytsi ligand for the group 13 element in bridging position [Pytsi = C(SiMe 3 ) 2 SiMe 2 (2-C 5 H 4 N)], as we had employed this ligand successfully in the synthesis of strained [1]metallacyclophanes ,,,, and low-coordinate aluminum cations before. This trisyl -based ligand was first synthesized by Eaborn and Smith et al and employed in subsequent chemistry …”

Section: Resultsmentioning

confidence: 99%

ansa-Zirconocenes with Aluminum or Gallium in Bridging Positions

Lund¹,

Hanson²,

Schatte

et al. 2010

Organometallics

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Bis(cyclopentadienyl)aluminum and -gallium species of the type (Pytsi)ECp2 [E = Al (2a), Ga (2b); Pytsi = C(SiMe3)2SiMe2(2-C5H4N)] have been prepared from NaCp and respective dichlorides (Pytsi)ECl2 in isolated yields of 65% (2a) and 83% (2b). In addition to applying standard methods of characterization (NMR spectroscopy, CHN analysis, and MS), the molecular structures of both compounds were solved by single-crystal X-ray crystallography. Reactions between 2a or 2b with Zr(NMe2)4 in benzene, followed by addition of an excess of ClSiMe3, gave the first ansa-zirconocene dichlorides with aluminum (4a) or gallium (4b) in bridging position. The gallium compound 4b was isolated in a yield of 40% and characterized by NMR spectroscopy, CHN analysis, and mass spectrometry. The aluminum species 4a could not be obtained in an analytically pure form; it was characterized by NMR spectroscopy, and its molecular structure was determined by single-crystal X-ray analysis. The angle between the two planes of the Cp ligands in 4a was found to be 57.17(11)°, which is larger than in Cp2ZrCl2 (α = 53.5°) and smaller than in silicon-bridged ansa-zirconocene dichlorides (e.g., Me2Si(C5H4)2ZrCl2: α = 60.1°). Crystallization attempts of 4a from DCCl3 solutions gave crystals of the new species (Pytsi)AlCl[(C5H4)ZrCp] (7), which was characterized by NMR spectroscopy and single-crystal X-ray analysis. In comparison to the Pytsi-containing species 2a and 2b, the less sterically protected compound [2-(Me2NCH2)C6H4]AlCp2 (6), which was prepared from NaCp and [2-(Me2NCH2)C6H4]AlCl2 in yields of 94% and characterized by standard methods (NMR, CHN, and MS), reacted with Zr(NMe2)4 to give the known Cp2Zr(NMe2)2. The targeted ansa-species was not formed, as judged by 1H NMR spectroscopy. The gallium-bridged compound 4b and Cp2ZrCl2, respectively, had been tested for polymerizations of ethylene utilizing MAO as an activator (300 equiv of MAO; 5 or 10 μmol of precatalyst; 15 or 70 psi), resulting in activities of 637 to 1080 for 4b and of 640 to 2601 kg PE (mol Zr)−1 h−1 atm−1 for Cp2ZrCl2.

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Section: Resultsmentioning

confidence: 99%

ansa-Zirconocenes with Aluminum or Gallium in Bridging Positions

Lund¹,

Hanson²,

Schatte

et al. 2010

Organometallics

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“…As expected, both species are monomers in the solid state, with nitrogen acting as an electron donor toward the Lewis acidic aluminum. The Al–N bond lengths of 1.984(2) and 1.996(2) Å for 2 and 1.936(4) Å for 3 Br are not strikingly different from values found in the related species (Pytsi)AlMe 2 (2.0034(18) Å), (Pytsi)AlCl 2 (1.9383(16) Å), and (Me 2 Ntsi)AlCl 2 (1.975(2) Å) (see Chart for Pytsi and Me 2 Ntsi). It is apparent from the thermal ellipsoid plots in Figures and that the most unusual structural parameter is the small bite angle of ligand R′, which was found to be 70.66(8) and 70.60(8)° for the dimethyl species 2 and 73.38(18)° for the bromide 3 Br .…”

Section: Resultsmentioning

confidence: 69%

Synthesis of Intramolecularly Coordinated Aluminum and Gallium Compounds for the Preparation of [1]Ferrocenophanes

et al. 2011

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Two different ligands equipped with pyridine donor moieties, (2-H4C5N)(Me3Si)2C (R′) and (2-H4C5N)(Me3Si)(Me)C (R″), were applied in the preparation of aluminum and gallium dihalides that could be employed in salt metathesis reactions with 1,1′-dilithioferrocene. R′GaCl2 (1) was accessible from LiR′ and GaCl3 (21%), whereas the respective aluminum compound R′AlCl2 (3 Cl ) and its bromine analogue R′AlBr2 (3 Br ) could only be prepared through the intermediate species R′AlMe2 (2) by the addition of Me3SnCl and Br2, respectively. An improved synthesis of the ligand precursor R″H, (2-H4C5N)(Me3Si)(Me)CH), is described. Attempted syntheses of R″AlX2 starting from LiR″ and AlCl3 or ClAlMe2 gave the bis-ligand compounds R″2AlCl (4) and R″2AlMe (6), respectively. As deduced from proton NMR spectroscopy, the formation of 6 proceeded through the intermediate R″AlMe2 (5) and was facilitated in the presence of tmeda. The formation of 4 and 6, respectively, is diastereospecific, as only rac isomers were formed (R,R-Λ and S,S-Δ). Molecular structures of compounds 2, 3 Br , and 6 were determined by single-crystal X-ray analysis. Salt metathesis of the dihalides 1, 3 Cl , and 3 Br with 1,1′-dilithioferrocene gave the respective galla- and alumina[1]ferrocenes (7 and 8). Neither compound could be isolated and were only identified by 1H NMR spectroscopy in reaction mixtures. Analytically pure polymers (7 n ) of low molecular weight were found and investigated by DLS (M w = 8.3 ± 2.5 kDa; DPw = 17 ± 5).

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“…Compound 1 had been described in a very recent publication by Hill and Smith . The authors mentioned a disorder of 1 in the crystal lattice; however, the molecular structure of 1 was not described.…”

Section: Resultsmentioning

confidence: 99%

“…In addition to the bulkiness of the trisyl ligand, α silyl effects contribute to a stabilization of an attached metal center. Several trisyl derivatives in which one or more methyl groups are replaced by substituents with Lewis-base donor capabilities are known, among which the pytrisyl ligand, C(SiMe 3 ) 2 SiMe 2 (2-C 5 H 4 N), is the most studied example. − Recently, we took advantage of the unique properties of the bulky and intramolecularly stabilizing pytrisyl ligand and synthesized [1]ferrocenophanes with aluminum and gallium in bridging positions.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Neutral and Cationic Intramolecularly Coordinated Aluminum Compounds. Structural Determination of [(Pytsi)AlMe]⁺[MeB(C₆F₅)₃]^- [(Pytsi = C(SiMe₃)₂SiMe₂(2-C₅H₄N)]

et al. 2005

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The synthesis and structure of neutral and cationic aluminum compounds equipped with the intramolecular donating C(SiMe3)2SiMe2(2-C5H4N) ligand denoted by Pytsi is described. The compounds (Pytsi)AlMe2 (1), (Pytsi)AlEt2 (2), [(Pytsi)AlMe]+[MeB(C6F5)3]- (3), and [(Pytsi)AlMe(thf)]+[MeB(C6F5)3]- (3·thf) have been synthesized and characterized by standard methods, and the molecular structures of 1, 2, and 3 have been determined by single-crystal X-ray analyses. Compound 3 was obtained by an addition of 1 equiv of B(C6F5)3 to the dimethyl species 1. The salt-like title compound 3 shows a methyl group in a bridging position between Al and B atoms consisting of a long Al−C distance of 2.380(2) Å and a B−C bond length of 1.681(3) Å.

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Organometallic compounds of Group 13 elements containing the ligand C(SiMe3)2(SiMe2C5H4N-2)

Cited by 12 publications

References 58 publications

ansa-Zirconocenes with Aluminum or Gallium in Bridging Positions

ansa-Zirconocenes with Aluminum or Gallium in Bridging Positions

Synthesis of Intramolecularly Coordinated Aluminum and Gallium Compounds for the Preparation of [1]Ferrocenophanes

Synthesis and Characterization of Neutral and Cationic Intramolecularly Coordinated Aluminum Compounds. Structural Determination of [(Pytsi)AlMe]⁺[MeB(C₆F₅)₃]^- [(Pytsi = C(SiMe₃)₂SiMe₂(2-C₅H₄N)]

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Organometallic compounds of Group 13 elements containing the ligand C(SiMe3)2(SiMe2C5H4N-2)

Cited by 12 publications

References 58 publications

ansa-Zirconocenes with Aluminum or Gallium in Bridging Positions

ansa-Zirconocenes with Aluminum or Gallium in Bridging Positions

Synthesis of Intramolecularly Coordinated Aluminum and Gallium Compounds for the Preparation of [1]Ferrocenophanes

Synthesis and Characterization of Neutral and Cationic Intramolecularly Coordinated Aluminum Compounds. Structural Determination of [(Pytsi)AlMe]+[MeB(C6F5)3]- [(Pytsi = C(SiMe3)2SiMe2(2-C5H4N)]

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Synthesis and Characterization of Neutral and Cationic Intramolecularly Coordinated Aluminum Compounds. Structural Determination of [(Pytsi)AlMe]⁺[MeB(C₆F₅)₃]^- [(Pytsi = C(SiMe₃)₂SiMe₂(2-C₅H₄N)]