(η3-tris(3-tert-butylpyrazolyl)hydroborato)MgOCH2CH3 | 125950-47-2

• 英文名称: (η3-tris(3-tert-butylpyrazolyl)hydroborato)MgOCH2CH3
• CAS: 125950-47-2
• 化学式: C₂₃H₃₉BMgN₆O
• 分子量: 450.718
• InChiKey: SVTWWGQLCPAKSG-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
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• 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

• 作为产物：
  描述：

  thallium(I) hydrotris(3-tert-butylpyrazol-1-yl)borate 以 四氢呋喃 、 乙醚 、 苯 为溶剂， 生成 (η3-tris(3-tert-butylpyrazolyl)hydroborato)MgOCH2CH3
  参考文献：
  名称：

  Molecular Design of Single-Site Metal Alkoxide Catalyst Precursors for Ring-Opening Polymerization Reactions Leading to Polyoxygenates. 1. Polylactide Formation by Achiral and Chiral Magnesium and Zinc Alkoxides, (η³-L)MOR, Where L = Trispyrazolyl- and Trisindazolylborate Ligands

  摘要：

  Single-site achiral and chiral C-3-symmetric complexes LMOR, where M = Mg and Zn, L = an eta (3)-trispyrazolyl- or eta (3)-trisindazolyl-borate ligand and R = Et, Bu-t, Ph, or SiMe3, have-been synthesized and employed in the ring-opening polymerization of L-, rac-, and meso-lactide in CH2Cl2 at 25 degreesC and below. The polymerization occurs by acyl cleavage and gives rise to polylactide, PLA, with PDI of 1.1-1.25 up to 90% conversion. Studies of the kinetics of polymerization reveal first order behavior in both lactide and metal catalyst. For L = tris(3-tert-butylpyrazolyl)borate, ((t)Bupz)(3)BH, polymerization of similar to 500 equiv of L-lactide proceeds to 90% conversion within 1 h and 6 d for the magnesium and zinc catalysts, respectively. The zinc complexes are, however, more tolerant to air and moisture and solid samples where R = SiMe3 are persistent in air for several days. The rate of polymerization is also significantly influenced by the nature of the eta (3)-L spectator li,ligand. Chiral C-3-symmetric catalysts, where L = tris(indazolyl)borates derived:from camphor and menthone, show only slight enantioselectivity in their polymerization of rac-lactide but do show significant diastereoselectivity in their ability to preferentially polymerize meso-lactide from a mixture of rac- and meso-lactide. The poly(mesolactide) shows a modest preference for syndiotactic junctions, RSRSRS. The molecular structures, deduced from single-crystal X-ray crystallography, are reported for eta (3)-HB(3-Phpz)(3)MgEt(THF), [eta (3)-HB((7R)-Pr-i-(4R)-Me-4,5,6,7-tetrahydro-2H-indazolyl)(3)]ZnMe and [eta (3)-HB(3-(t)Bupz)(3,5-(CF3)(2)pz)(2)]-ZnOSiMe3 and serve as structural models for activated and ground-state configurations of the metal ions during the polymerization reaction. The molecular structure of meso-lactide is also reported. These results are compared with polymerizations of lactide by other coordinate catalysts.

  DOI：

  10.1021/ja002160g

文献信息

• [Tris(pyrazolyl)hydroborato]magnesium alkyl derivatives: reactivity studies
  作者：Runyu Han、Gerard Parkin

  DOI：10.1021/ja00028a051

  日期：1992.1

  The reactivity of a series of 4-coordinate [tris(pyrazolyl)hydroborato]magnesium alkyl derivatives, eta-3-HB(3-Bu(t)pz)3}MgR and eta-3-HB(3,5-Me2pz)3}MgR (3-Bu(t)pz = 3-C3N2Bu(t)H2, 3,5-Me2pz = 3,5-C3N2Me2H; R = CH3, CH2CH3, (CH2)3CH3, CH(CH3)2, C(CH3)3, CH = CH2, C6H5, CH2SiMe3), has been investigated. The complexes eta-3-HB(3,5-Me2pz)3}MgR undergo ligand redistribution reactions, analogous to the Schlenk equilibrium, to give the 6-coordinate sandwich complex eta-3-HB-(3,5-Me2pz)3}2Mg. In contrast, the 4-coordinate magnesium alkyl derivatives supported by the more sterically demanding tris(3-tert-butylpyrazolyl)hydroborato ligand, eta-3-HB(3-Bu(t)pz)3}MgR, are stable with respect to the formation of eta-3-HB(3-Bu(t)pz)3}2Mg. The alkyl complexes eta-3-HB(3-Bu(t)pz)3}MgR are useful precursors for a variety of other 4-coordinate complexes, including eta-3-HB(3-Bu(t)pz)3}MgX (X = C = CC6H5, C = CSiMe3, OEt, OPr(i), OBu(t), OPh, OCH2SiMe3, OSiMe3, OOBu(t), NHPh, SH, SCH3, Cl, Br, I, NCO, NCS). CO2 inserts into the Mg-C bond of eta-3-HB(3-Bu(t)pz)3}MgCH3 to give the eta-1-acetato complex eta-3-HB(3-Bu(t)pz)3}Mgeta-1-OC(O)CH3}. In contrast, the reactions with the ketones CH3C(O)CH3 and CH3C(O)Bu(t) do not result in insertion to give the alkoxide derivatives, but preferentially give the enolate complexes eta-3-HB(3-Bu(t)pz)3}Mgeta-1-OC(= CH2)CH3} and eta-3-HB(3-Bu(t)pz)3}Mgeta-1-OC(= CH2)Bu(t)}, accompanied by the elimination of methane. Insertion of O2 into the Mg-R bond of the complexes eta-3-HB(3-Bu(t)pz)3}MgR (R = CH3, CH2CH3, CH(CH3)2, C(CH3)3) results in formation of the alkylperoxo derivatives eta-3-HB(3-Bu(t)pz)3}MgOOR, which have been characterized by the use of O-17 NMR spectroscopy. In contrast, the reaction of the magnesium (trimethylsilyl)methyl complex eta-3-HB(3-Bu(t)pz)3}MgCH2SiMe3 with O2 gives the trimethylsiloxide derivative eta-3-HB(3-Bu(t)pz)3}MgOSiMe3 as result of facile cleavage of the Si-C bond upon autoxidation. The molecular structures of eta-3-HB(3,5-Me2pz)3}2Mg and eta-3-HB(3-Bu(t)pz)3}MgCl have been determined by X-ray diffraction. Eta-3-HB-(3,5-Me2pz)3]2Mg is triclinic, P1BAR (No. 2), a = 8.837 (3) angstrom, b = 10.223 (3) angstrom, c = 10.772 (2) angstrom, alpha = 63.92 (3)-degrees, beta = 85.24 (2)-degrees, gamma = 79.87 (2)-degrees, V = 860.4 (4) angstrom3, Z = 1. Eta-3-HB(3-Bu(t)pz)3}MgCl is orthorhombic, Pnma (No. 62), a = 16.048 (7) angstrom, b = 16.006 (3) angstrom, c = 9.840 (1) angstrom, V = 2527 (1) angstrom3, Z = 4.