| 176544-34-6

• 分子结构分类: 有机化合物 - 有机氧化合物
• CAS: 176544-34-6
• 化学式: C₄₈H₁₁₀O₄Si₄W₂
• 分子量: 1231.44
• InChiKey: XTPVOUFYYKHWMM-UHFFFAOYSA-N

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：

  以 环己烷 为溶剂， 生成
  参考文献：
  名称：

  Ditungsten Siloxide Hydrides, [(silox)₂WH_n]₂ (n = 1, 2; silox = ^tBuSiO), and Related Complexes

  摘要：

  The addition of 4.0 equiv of Na(silox) to Na[W2Cl7(THF)(5)] afforded (silox)(2)ClW=WCl(silox)(2) (1, 65%). Treatment of 1 with 2.0 equiv of McMgBr in Et(2)O provided (silox)(2)MeW=WMe(silox)(2) (2, 81%). In the presence of 1 atm of H-2, reduction of 1 with 2.0 equiv of Na/Hg in DME provided (silox)(2)HW=WH(silox)(2) (3, 70%), characterized by a hydride resonance at delta 19.69 (J(WH) = 325 Hz, H-1 NMR). Exposure of 2 to 1 atm of H-2 yielded 3 and CH4 via (silox)(2)HW=WMe(silox)(2) (4); use of D-2 led to [(silox)(2)WD](2) (3-d(2)). Exposure of 3 to ethylene (similar to 1 atm, 25 degrees C) in hexanes generated (silox)(2)EtW=WEt(silox)(2) (5), but solutions of 5 reverted to 3 and free C2H4 upon standing. NMR spectral data are consistent with a sterically locked, gauche, C-2 symmetry for 1-5. Thermolysis of 3 at 100 degrees C (4 h) resulted in partial conversion to (silox)(2)HW=W(OSi(t)Bu(2)CMe(2)CH(2))(silox) (6a, similar to 60%) and free H-2, while extended thermolysis with degassing (5 d, 70 degrees C) produced a second cyclometalated rotational isomer, 6b (6a:6b similar to 3:1). When left at 25 degrees C (4 h) in sealed NMR tubes, 6 and free H-2 regenerated 3. Reduction of 1 with 2.0 equiv of Na/Hg in DME also afforded 6a (25%). When 3 was exposed to similar to 3 atm of H-2, equilibrium amounts of [(silox)(2)WH2](2) (7) were observed by H-1 NMR spectroscopy (3 + H-2 reversible arrow 7; 25.9-88.7 degrees C, Delta H = -9.6(4) kcal/mol, Delta S = -21(2) eu). Benzene solutions of 3 and 1-3 atm of D-2 revealed incorporation of deuterium into the silox ligands, presumably via intermediate 6. In sealed tubes containing [(silox)(2)WCl](2) (1) and dihydrogen (1-3 atm), H-1 NMR spectral evidence for [(silox)(2)WCl](2)(mu-H)(2) (8) was obtained, suggesting that formation of 3 from 1 proceeded via reduction of 8. Alternatively, 3 may be formed from direct reduction of 1 to give [(silox)(2)W](2) (9), followed by H-2 addition. Hydride chemical shifts for 7 are temperature dependent, varying from delta 1.39 (-70 degrees C, toluene-d(8)), to delta 3.68 (90 degrees C). Si-29{H-1} NMR spectra revealed a similar temperature dependence of the silox (delta 12.43, -60 degrees C, to delta 13.64, 45 degrees C) resonances. These effects may arise from thermal population of a low-lying, delta delta*, paramagnetic excited state of D-2d [(silox)(2)W](2)(mu-H)(4) (Delta E similar to 2.1 kcal/mol, (chi)(7a*) similar to 0.03), an explanation favored over thermal equilibration with an energetically similar but structurally distinct isomer (e.g., [(silox)(2)WH2](2)(mu-H)(2), Delta G degrees similar to 0.69 kcal/mol, (chi)(7b) similar to 0.25) on the basis of spectral arguments.Extended Huckel and ab initio molecular orbital calculations on model complexes [(H3SiO)(2)W](2)(mu-H)(4) (staggered bridged 7a', EHMO), [(H3SiO)(2)WH2](2) (all-terminal 7b', EHMO), [(H3SiO)(2)W](2) (9', EHMO), (HO)(4)W-2(H-4) (staggered-bridged 7'', ab initio), and (HO)(4)W-2(H-4) (bent-terminal 7*, ab initio) generally support the explanation of a thermally accessible excited state and assign 7* a geometry intermediate between the all-terminal and staggered-bridged forms.

  DOI：

  10.1021/ic9513191
• 作为产物：
  描述：

  Na(silox) 以 乙醚 、 甲苯 为溶剂， 生成
  参考文献：
  名称：

  Ditungsten Siloxide Hydrides, [(silox)₂WH_n]₂ (n = 1, 2; silox = ^tBuSiO), and Related Complexes

  摘要：

  The addition of 4.0 equiv of Na(silox) to Na[W2Cl7(THF)(5)] afforded (silox)(2)ClW=WCl(silox)(2) (1, 65%). Treatment of 1 with 2.0 equiv of McMgBr in Et(2)O provided (silox)(2)MeW=WMe(silox)(2) (2, 81%). In the presence of 1 atm of H-2, reduction of 1 with 2.0 equiv of Na/Hg in DME provided (silox)(2)HW=WH(silox)(2) (3, 70%), characterized by a hydride resonance at delta 19.69 (J(WH) = 325 Hz, H-1 NMR). Exposure of 2 to 1 atm of H-2 yielded 3 and CH4 via (silox)(2)HW=WMe(silox)(2) (4); use of D-2 led to [(silox)(2)WD](2) (3-d(2)). Exposure of 3 to ethylene (similar to 1 atm, 25 degrees C) in hexanes generated (silox)(2)EtW=WEt(silox)(2) (5), but solutions of 5 reverted to 3 and free C2H4 upon standing. NMR spectral data are consistent with a sterically locked, gauche, C-2 symmetry for 1-5. Thermolysis of 3 at 100 degrees C (4 h) resulted in partial conversion to (silox)(2)HW=W(OSi(t)Bu(2)CMe(2)CH(2))(silox) (6a, similar to 60%) and free H-2, while extended thermolysis with degassing (5 d, 70 degrees C) produced a second cyclometalated rotational isomer, 6b (6a:6b similar to 3:1). When left at 25 degrees C (4 h) in sealed NMR tubes, 6 and free H-2 regenerated 3. Reduction of 1 with 2.0 equiv of Na/Hg in DME also afforded 6a (25%). When 3 was exposed to similar to 3 atm of H-2, equilibrium amounts of [(silox)(2)WH2](2) (7) were observed by H-1 NMR spectroscopy (3 + H-2 reversible arrow 7; 25.9-88.7 degrees C, Delta H = -9.6(4) kcal/mol, Delta S = -21(2) eu). Benzene solutions of 3 and 1-3 atm of D-2 revealed incorporation of deuterium into the silox ligands, presumably via intermediate 6. In sealed tubes containing [(silox)(2)WCl](2) (1) and dihydrogen (1-3 atm), H-1 NMR spectral evidence for [(silox)(2)WCl](2)(mu-H)(2) (8) was obtained, suggesting that formation of 3 from 1 proceeded via reduction of 8. Alternatively, 3 may be formed from direct reduction of 1 to give [(silox)(2)W](2) (9), followed by H-2 addition. Hydride chemical shifts for 7 are temperature dependent, varying from delta 1.39 (-70 degrees C, toluene-d(8)), to delta 3.68 (90 degrees C). Si-29{H-1} NMR spectra revealed a similar temperature dependence of the silox (delta 12.43, -60 degrees C, to delta 13.64, 45 degrees C) resonances. These effects may arise from thermal population of a low-lying, delta delta*, paramagnetic excited state of D-2d [(silox)(2)W](2)(mu-H)(4) (Delta E similar to 2.1 kcal/mol, (chi)(7a*) similar to 0.03), an explanation favored over thermal equilibration with an energetically similar but structurally distinct isomer (e.g., [(silox)(2)WH2](2)(mu-H)(2), Delta G degrees similar to 0.69 kcal/mol, (chi)(7b) similar to 0.25) on the basis of spectral arguments.Extended Huckel and ab initio molecular orbital calculations on model complexes [(H3SiO)(2)W](2)(mu-H)(4) (staggered bridged 7a', EHMO), [(H3SiO)(2)WH2](2) (all-terminal 7b', EHMO), [(H3SiO)(2)W](2) (9', EHMO), (HO)(4)W-2(H-4) (staggered-bridged 7'', ab initio), and (HO)(4)W-2(H-4) (bent-terminal 7*, ab initio) generally support the explanation of a thermally accessible excited state and assign 7* a geometry intermediate between the all-terminal and staggered-bridged forms.

  DOI：

  10.1021/ic9513191

文献信息

• Ethylene and Alkyne Carbon−Carbon Bond Cleavage across Tungsten−Tungsten Multiple Bonds
  作者：Rebecca L. M. Chamberlin、Devon C. Rosenfeld、Peter T. Wolczanski、Emil B. Lobkovsky

  DOI：10.1021/om020037n

  日期：2002.6.1

  Treatment of [(silox)(2)WH](2) (1) with RCdropCR'(R = R'= H, CH3; R = H, R'= Ph) afforded thermally unstable [(silox)(2)W](2)(mu:eta(2),eta(2) -RCCR')(mu-H)(2) (R = R'= H, 2a; CH3,2b; R = H, R'= Ph, 2c), which lose H-2 and convert to [(silox)(2)W](2)(mu-CR)(mu-CR') (R = R'= H, 4a; CH3, 4b; R = H, R' = Ph, 4c). An X-ray structural study of 4b revealed a nearly square W2C2 core and a d(WW) of 2.720(2) Angstrom. Thermal degradation of 1(silox)(2)W(CH2CH3)](2) (5) also produced 4b, and with 2 equiv Of C2H4, its formation is nearly quantitative with 2 equiv of EtH as a byproduct. Na/Hg reduction of (silox)(2)C]WdropWCl(silox)(2) (3) in the presence of excess 2-butyne afforded [(silox)(2)W](2)(mu:eta(2),eta(2)-MeC2Me) (8), which could be treated with H2 to give 2b or thermolyzed to 4b. A similar reduction of 3 with excess ethylene present afforded 4a via [(silox)(2)W](2)(mu-CH)(mu-CH2)(H) (9, -78 degreesC) followed by H-2 loss; ethylene cleavage does not proceed via 2a or 8. Related cleavage chemistry was not observed for [(silox)(2)TaH2](2) (10) and excess ethylene, which formed (SilOX)2HTaEt]2 (11) and, ultimately, [(silox)(2)HTaEt](2) (mu-CHCH2)(mu-H)(2)[Ta(silox)(2)] (12) and EtH. An X-ray structural study of 12 confirmed its configuration. Spectroscopic features of the molecules are addressed, and plausible mechanisms of carbon-carbon bond cleavage-whose thermodynamic impetus is the formation of mu-CR bridges-are discussed.