carbanide;1,2,3,4,5-pentamethylcyclopenta-1,3-diene;2,2,4,4-tetramethylpentan-3-ylideneazanide;titanium(4+) | 221621-07-4

• 分子结构分类: 有机化合物 - 碳氢化合物衍生物
• 英文名称: carbanide;1,2,3,4,5-pentamethylcyclopenta-1,3-diene;2,2,4,4-tetramethylpentan-3-ylideneazanide;titanium(4+)
• CAS: 221621-07-4
• 化学式: C₂₁H₃₉NTi
• 分子量: 353.427
• InChiKey: IZGZZMFNHFHSHC-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  None
• 重原子数：
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• 可旋转键数：
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• 环数：
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• sp3杂化的碳原子比例：
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• 拓扑面积：
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• 氢给体数：
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• 氢受体数：
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反应信息

• 作为反应物：
  描述：

  carbanide;1,2,3,4,5-pentamethylcyclopenta-1,3-diene;2,2,4,4-tetramethylpentan-3-ylideneazanide;titanium(4+) 、 三苯碳四(五氟苯基)硼酸盐 以 further solvent(s) 为溶剂， 生成 carbanide;1,2,3,4,5-pentamethylcyclopenta-1,3-diene;tetrakis(2,3,4,5,6-pentafluorophenyl)boranuide;2,2,4,4-tetramethylpentan-3-ylideneazanide;titanium(4+)
  参考文献：
  名称：

  Methane Loss from Cationic μ-Methyl Dimers Formed via Trityl Borate Activation of Monocyclopentadienyl Ketimide Complexes Cp[(^tBu)₂CN]Ti(CH₃)₂ (Cp = C₅H₅, C₅Me₅, C₅Me₄SiMe₃)

  摘要：

  The reactions of the monocyclopentadienyl titanium dimethyl compounds Cp(L)TiMe2 (L = (Bu2C)-Bu-t=N; Cp = C5H5, 18; C5Me5, Ib; C5Me4SiMe3, Ic) with the trityl borate activator [Ph3C](+)[B(C6F5)(4)](-) are described. Formation of Ic-methyl dimers of formula {[Cp(L)TiMe](2)(mu -Me)}(+)[B(C6F5)(4)](-) as a 1:1 mixture of rac and meso diastereomers is observed when 0.5 equiv of [Ph3C](+)[B(C6F5)(4)](-) is employed (-25 degreesC, C6D5Br; Cp = C5H5, rac/meso 2a; C5Me5, rac/meso 2b; C5Me4SiMe3, rac/meso 2c). Dynamic NMR and crossover experiments suggest that the dimers 2 are relatively nonlabile with respect to dissociation, intramolecular methyl group exchange, or diastereomer interconversion. Dimers 2 are observed to undergo methane loss in solution at room temperature, affording the new dimeric compounds 3a-c, ([Cp(L)Ti] (2)(mu -CH2)(mu -CH3)}(+)[B(C6F5)(4)](-) For the less sterically demanding C5H5 ligand, 3a is formed as a mixture of rac/meso diastereomers (7:3), but for the bulkier C5Me5 and C5Me4SiMe3 ligands, the rac isomers of 3b and 3c are formed exclusively. In contrast to mu -methyl dimers 2, in which rac/meso interconversion is not observed, the diastereomers of 3 do undergo interchange, as determined by EXSY spectroscopy, and thus the rac/meso ratios observed are thermodynamic.

  DOI：

  10.1021/om010130w
• 作为产物：
  描述：

  [Ti(η5-C5Me5)(N=C(t-Bu)2)Cl2] 、 甲基溴化镁 以 乙醚 、 甲苯 为溶剂， 以89%的产率得到carbanide;1,2,3,4,5-pentamethylcyclopenta-1,3-diene;2,2,4,4-tetramethylpentan-3-ylideneazanide;titanium(4+)
  参考文献：
  名称：

  The Mechanism of Methane Elimination in B(C₆F₅)₃-Initiated Monocyclopentadienyl-Ketimide Titanium and Related Olefin Polymerization Catalysts

  摘要：

  A new class of monocyclopentadienyl titanium olefin polymerization catalysts and their activation with B(C6F5)(3) is reported herein. Dichlorides Cp[Bu-t(R)C=N]TiCl2 {Cp = C5H5, R = Bu-t (1a); Cp = C5Me5, R = Bu-t (2a); Cp = C5Me4SiMe3, R = Bu-t (3a); Cp = C5Me5, R = CH2SiMe3 (4a); Cp = C5Me5, R = Me (5a)} were prepared in 50-92% yield from CpTiCl3 and Bu-t(R)C=NLi. Analogous dimethyl compounds 1b-5b were prepare via methylation of dichlorides a using MeMgBr in 89-92% yield. Dimethyl compound 6b (L = C5Me5, R = CH(SiMe3)(2)) was prepared directly from Cp*TiMe3 and Bu-t[(Me3Si)(2)CH]C=NH in 40% yield. Dynamic H-1 NMR studies showed that the ketimide ligands in compounds b rotate rapidly about Ti-N on the NMR time scale, with a a Delta G(double dagger) of 9.6(6) kcal mol(-1) or less. The mixed alkyl compound Cp*-[Bu-t(R)C=N]Ti(CH3)CH2SiMe3 {R = (t)3u (7)} was prepared via alkylation of the corresponding methyl chloride derivative with BrMgCH2SiMe3. When treated with B(C6F5)(3), compounds 1b-6b are rapidly converted into the ion pairs {Cp[Bu-t(R)C=N]TiCH3}(+)[H3C(B(C6F5)(3)](-), 1c-6c; mixed alkyl compound 7 yields the ion pair [Cp*((Bu2C)-Bu-t=N)TiCH2SiMe3](+)[H3C(B(C6F5)(3)](-), 7c, exclusively. Multinuclear NMR experiments show that ion pairing is tight in these compounds and that ketimide ligand rotation is occurring with a slightly higher barrier in comparison to the neutral derivatives b. Ion pairs 1c-5e undergo a decomposition process involving loss of methane and producing the neutral compounds Cp[Bu-t(R)C=N]Ti(C6F5)[CH2B(C6F5)(2)], 1d-5d. The X-ray crystal structure of Id has been determined. Active cationic compounds are not regenerated from neutral compounds d in the presence of B(C6F5)(3) and thus this reaction is a potential deactivation pathway for these particular ion pairs. Detailed kinetic studies on the decomposition of 2c show the reaction to be first order in [2c] with activation parameters of Delta H-double dagger = 20.6(8) kcal mol(-1) and Delta S-double dagger = -8.5(10) eu, corresponding to Delta G(298)(double dagger) of 23.1(8) kcal mol(-1). A substantial kinetic isotope effect of k(H)/k(D) = 9.1(6) was measured using d(6)-2c. Further mechanistic experiments, including crossover and examination of alkane elimination from mixed alkyl ion pair 7c, point to a sigma-bond metathesis mechanism for the production of compounds d. The implications of our results for other, related catalyst systems are discussed.

  DOI：

  10.1021/ja994378c