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首页> 外文学位 >Thermodynamic and kinetic investigation of oxygen atom transfer to phosphines, metal phosphido and vanadium(III) complexes: Mechanistic differences and effect of axial base coordination on metal chalcogen bonds.
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Thermodynamic and kinetic investigation of oxygen atom transfer to phosphines, metal phosphido and vanadium(III) complexes: Mechanistic differences and effect of axial base coordination on metal chalcogen bonds.

机译：氧原子转移至膦，金属磷化氢和钒（III）配合物的热力学和动力学研究：机理差异和轴向碱配位对金属硫属元素键的影响。

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摘要

As we try to find ways to oxidize atmospheric nitrogen, it becomes important to us to understand oxygen atom transfer (OAT) reactions. We began with understanding OAT to different types of tri substituted phosphines (PR3, R=alkyl, aryl). We used mesityl nitrile oxide (MesCNO) as OAT reagent. We explored thermodynamic, kinetic, mechanistic pathways of OAT and figured out the differences in P=O bond strength as well as the effect of different substitutions (R groups in PR3) on the rate of OAT. With the help of computational analyses, we found that the is initial interaction between phosphorous and carbon of MesCNO. We wanted to explore the C=O bond strengths in NHC carbenes as they are electronically similar to phosphines by performing OAT from MesCNO. Instead of OAT, we made NHC-MesCNO adducts where the carbine carbon and the carbon of CNO in MesCNO were connected. This further solidified our theory of previously proposed phosphine-MesCNO intermediate through R3P˙˙˙˙C(Mes)NO interaction. These adducts showed higher rate of OAT compared to MesCNO itself. That encouraged us to explored the chemistry of these adducts. Not only by MesCNO, we also explored adducts formed between MesCNO and several isocyanates (RNCO, R=Ph, adamentyl, 2,6-di (trifluoro methyl) phenyl). Isocyanate adducts showed higher dipolemoment compared to MesCNO adducts. We, then moved on from OAT to non-metal such as phosphines to early transition metal complex such as vanadium tris anilide. In this instance we used several OAT reagents containing N-O bonds with different bond strengths. They showed significant differences in mechanism in OAT. Unfortunately, VO bond strength too great to transfer the oxygen from vanadium. We used another vanadium complex, V[(Me3SiNCH 2CH2)3N] with axial amine ligand and observed that VO bond strength decreases due to the presence of the axial amine ligand. Adducts formed between Ad-NC (Ad=adamantyl) and two vanadium complexes mentioned previously showed the same type of bond weakening due to the axial ligand. We tried to react vanadium tris anilide with molecular oxygen as it seemed thermodynamically favored to make vanadium oxide due to strong VO bond and expected to form high energy oxygen atom that could be used as effective OAT reagent. To our surprise they made peroxy vanadium complex. This complex was rather interesting because it has the potential to do further OAT. In this work we have explored significant aspects of OAT in depth which exposes valuable insights in catalytic and organometallic chemistry.
机译：当我们尝试寻找氧化大气中氮的方法时，了解氧原子转移（OAT）反应对我们来说变得很重要。我们从了解OAT对不同类型的三取代膦（PR3，R =烷基，芳基）开始。我们使用异丁烯腈氧化物（MesCNO）作为OAT试剂。我们探索了OAT的热力学，动力学，机理途径，并找出了P = O键强度的差异以及不同取代基（PR3中的R基团）对OAT速率的影响。借助计算分析，我们发现MesCNO的磷与碳之间存在初始相互作用。我们想通过在MesCNO中进行OAT探索NHC卡宾碳中的C = O键强度，因为它们在电子学上类似于膦。代替OAT，我们制作了NHC-MesCNO加合物，其中将卡宾碳和MesCNO中的CNO碳相连。这进一步巩固了我们先前通过R 3 P点C（Mes）NO相互作用提出的膦-MesCNO中间体的理论。与MesCNO本身相比，这些加合物显示出更高的OAT率。这鼓励我们探索这些加合物的化学性质。不仅是MesCNO，我们还研究了MesCNO与几种异氰酸酯（RNCO，R = Ph，金刚烷基，2,6-二（三氟甲基）苯基）之间形成的加合物。与MesCNO加合物相比，异氰酸酯加合物显示出更高的偶极矩。然后，我们从OAT转向非金属（例如膦），再到早期过渡金属络合物（例如三苯胺钒）。在这种情况下，我们使用了几种包含具有不同键强度的N-O键的OAT试剂。他们在OAT的机制上显示出显着差异。不幸的是，VO键强度太大，无法从钒中转移氧。我们使用了另一个带有轴向胺配体的钒配合物V [（Me3SiNCH 2CH2）3N]，观察到由于轴向胺配体的存在，VO键强度降低。由于轴向配体，Ad-NC（Ad =金刚烷基）与两种钒配合物之间形成的加合物显示出相同类型的键弱。我们试图使三氨基苯甲酸钒与分子氧反应，因为由于强大的VO键，热力学上似乎有利于制备氧化钒，并有望形成可以用作有效OAT试剂的高能氧原子。令我们惊讶的是，他们制造了过氧钒络合物。这个复合体非常有趣，因为它有可能做进一步的OAT。在这项工作中，我们深入研究了OAT的重要方面，从而揭示了催化和有机金属化学方面的宝贵见解。

著录项

  • 作者

    Majumdar, Subhojit.;

  • 作者单位

    University of Miami.;

  • 授予单位 University of Miami.;
  • 学科 Atmospheric chemistry.
  • 学位 Ph.D.
  • 年度 2016
  • 页码 266 p.
  • 总页数 266
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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