chlorobis(cyclopentadienyl)(2,2,6,6-tetramethylpiperidine-N-oxyl)titanium | 90187-94-3

• 英文名称: chlorobis(cyclopentadienyl)(2,2,6,6-tetramethylpiperidine-N-oxyl)titanium
• 英文别名: Ti(cyclopentadienyl)2Cl(2,2,6,6-tetramethylpiperidine-N-oxyl)；[(η5-C5H5)2TiCl(2,2,6,6-tetramethylpiperidine-1-oxyl)]
• CAS: 90187-94-3
• 化学式: C₁₉H₂₈ClNOTi
• 分子量: 369.77
• InChiKey: WCYHPIZPUUUVSM-UHFFFAOYSA-M

计算性质

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

反应信息

• 作为反应物：
  描述：

  氧化苯乙烯 、 chlorobis(cyclopentadienyl)(2,2,6,6-tetramethylpiperidine-N-oxyl)titanium 以 氘代苯 为溶剂， 生成 chlorobis(cyclopentadienyl)titanium(OCH₂CH(Ph)ONC₅H₆Me₄)
  参考文献：
  名称：

  Homolysis of Weak Ti−O Bonds:  Experimental and Theoretical Studies of Titanium Oxygen Bonds Derived from Stable Nitroxyl Radicals

  摘要：

  Titanium-oxygen bonds derived from stable nitroxyl radicals are remarkably weak and can be homolyzed at 60 degrees C. The strength of these bonds depends sensitively on the ancillary ligation at titanium. Direct measurements of the rate of Ti-O bond homolysis in Ti-TEMPO complexes CP2TiCl(TEMPO) (3) and Cp2TiCl(4-MeO-TEMPO) (4) (TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl, 4-MeO-TEMPO = 2,2,6,6-tetramethyl-4-methoxypiperidine-N-oxyl) were conducted by nitroxyl radical exchange experiments. Eyring plots gave the activation parameters, Delta H-double dagger = 27(+/- 1) kcal/mol, Delta S-double dagger = 6.9(+/- 2.3) eu for 3 and Delta H-double dagger = 28(+/- 1) kcal/mol, Delta S-double dagger = 9.0(+/- 3.0) eu for 4, consistent with a process involving the homolysis of a weak Ti-O bond to generate the transient Cp2Ti(III)Cl and the nitroxyl radical. Thermolysis of the titanocene TEMPO complexes in the presence of epoxides leads to the Cp2Ti(III)Cl-mediated ring-opening of the epoxide followed by trapping by the nitroxyl radical. The X-ray crystal structure of the Ti-TEMPO derivative, Cp2TiCl(4-MeO-TEMPO) (4), is reported. DFT (B3LYP/6-31G*) calculations and experimental studies reveal that the strength of the Ti-O bond decreases dramatically with the number of cyclopentadienyl groups on titanium. The calculated Ti-O bond strength of the monocyclopentadienyl complex 2 is 43 kcal/mol, whereas that of the biscyclopentadienyl complex 3 is 17 kcal/mol, a difference of 26 kcal/mol. These studies reveal that the strength of these Ti-O bonds can be tuned over an interesting and experimentally accessible temperature range by appropriate ligation on titanium.

  DOI：

  10.1021/ja044512f
• 作为产物：
  描述：

  2,2,6,6-四甲基哌啶氧化物 、 chlorobis(cyclopentadienyl)(2,2,6,6-tetramethyl-4-methoxypiperidine-N-oxyl)titanium 以 氘代苯 为溶剂， 生成 chlorobis(cyclopentadienyl)(2,2,6,6-tetramethylpiperidine-N-oxyl)titanium
  参考文献：
  名称：

  Homolysis of Weak Ti−O Bonds:  Experimental and Theoretical Studies of Titanium Oxygen Bonds Derived from Stable Nitroxyl Radicals

  摘要：

  Titanium-oxygen bonds derived from stable nitroxyl radicals are remarkably weak and can be homolyzed at 60 degrees C. The strength of these bonds depends sensitively on the ancillary ligation at titanium. Direct measurements of the rate of Ti-O bond homolysis in Ti-TEMPO complexes CP2TiCl(TEMPO) (3) and Cp2TiCl(4-MeO-TEMPO) (4) (TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl, 4-MeO-TEMPO = 2,2,6,6-tetramethyl-4-methoxypiperidine-N-oxyl) were conducted by nitroxyl radical exchange experiments. Eyring plots gave the activation parameters, Delta H-double dagger = 27(+/- 1) kcal/mol, Delta S-double dagger = 6.9(+/- 2.3) eu for 3 and Delta H-double dagger = 28(+/- 1) kcal/mol, Delta S-double dagger = 9.0(+/- 3.0) eu for 4, consistent with a process involving the homolysis of a weak Ti-O bond to generate the transient Cp2Ti(III)Cl and the nitroxyl radical. Thermolysis of the titanocene TEMPO complexes in the presence of epoxides leads to the Cp2Ti(III)Cl-mediated ring-opening of the epoxide followed by trapping by the nitroxyl radical. The X-ray crystal structure of the Ti-TEMPO derivative, Cp2TiCl(4-MeO-TEMPO) (4), is reported. DFT (B3LYP/6-31G*) calculations and experimental studies reveal that the strength of the Ti-O bond decreases dramatically with the number of cyclopentadienyl groups on titanium. The calculated Ti-O bond strength of the monocyclopentadienyl complex 2 is 43 kcal/mol, whereas that of the biscyclopentadienyl complex 3 is 17 kcal/mol, a difference of 26 kcal/mol. These studies reveal that the strength of these Ti-O bonds can be tuned over an interesting and experimentally accessible temperature range by appropriate ligation on titanium.

  DOI：

  10.1021/ja044512f

文献信息

• Coordination Chemistry of Stable Radicals:  Homolysis of a Titanium−Oxygen Bond
  作者：Kuo-Wei Huang、Robert M. Waymouth

  DOI：10.1021/ja0264854

  日期：2002.7.1

  Thermolysis of Cp2TiCl(TEMPO) (TEMPO = 2,2,6,6-tetramethylpiperidine-1-oxyl) at 60 degrees C in a benzene/CCl4 mixture generates Cp2TiCl2. Kinetic studies implicate a mechanism involving the reversible cleavage of a Ti-O bond to generate the TEMPO radical and Cp2TiCl, which is trapped by CCl4 to give Cp2TiCl2. The rate of this reaction is strongly inhibited by added TEMPO and increases with increasing

  Cp2TiCl(TEMPO)（TEMPO = 2,2,6,6-四甲基哌啶-1-氧基）在 60 摄氏度的苯/四氯化碳混合物中热解生成 Cp2TiCl2。动力学研究暗示了一种涉及 Ti-O 键可逆断裂以产生 TEMPO 自由基和 Cp2TiCl 的机制，后者被 CCl4 捕获以产生 Cp2TiCl2。该反应的速率受到添加 TEMPO 的强烈抑制，并随着 浓度的增加而增加，表明 TEMPO 与 Cp2TiCl 的偶联比从 中提取氯原子更快。