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Experimental and Theoretical Investigations of Anion-pi Interactions Metallacyclic Architectures of First-Row Transition Metals and N-Heteroaromatic Ligands

机译：第一行过渡金属和N-杂芳族配体的阴离子-π相互作用金属环结构的实验和理论研究

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Research into anion-pi interactions has shifted from attempts to establish the legitimacy of the interaction to the incorporation of anion-pi interactions into supramolecular architectures. The research discussed in this dissertation explores the subtle effects of ligand, anion, and metal ion on supramolecular architectures of tetrazine-based ligands in the context of anion-pi interactions and their importance in the design and synthesis of supramolecular architectures. Computational studies highlight the importance of the arene quadrupole moment, molecular polarizability, and substituent effects on the strength of anion-pi interactions. More importantly, however, this work establishes that there is a distinct directionality inherent to the anion-pi interaction between polyatomic anions and N-heterocycles, which can be used to direct ligands in supramolecular architectures as demonstrated through the work of the Dunbar group in recent years, particularly that of the square and pentagonal metallacycles.The extension of metallacycles of bptz to CoII and FeII demonstrates the ability to tune the size of the metallacyclic cavity by simply changing the metal ion and results in the surprising encapsulation of two [SbF6]- anions in [Fe5(bptz)5(NCCH3)10][SbF6]10. 1H NMR spectroscopy and electrochemical studies reveal slight but significant differences characteristic of the square and pentagonal metallacycles and support the presence of anion-pi interactions in solution and highlight the importance of the encapsulated anion in the templation and stability of the metallacycles. A study of the interconversion between the square and pentagonal metallacycles via 1H NMR is presented for the first time.Increasing the pi-acidity of the chelating ligand from bptz to bmtz results in the encapsulation of only one [SbF6]- anion in [Fe5(bmtz)5(NCCH3)10][SbF6]10, maximizing anion-pi interactions with the ligand despite the tighter fit. A significant hurdle in the incorporation of different anions into the metallacyclic structures was overcome with the development of a new synthetic protocol for [Fe(NCCH3)6]2+ salts of a wide range of anions from sodium salts and Fe4Cl8(THF)6. Also, the nuclearity of the less stable [Fe5(bptz)5(NCCH3)10][PF6]10 metallacycle was established via a combination of MS, electrochemistry and 1H NMR experiments through comparisons with known FeII metallacycle solution behavior.
机译：对阴离子-π相互作用的研究已从建立相互作用合法性的尝试转变为将阴离子-π相互作用纳入超分子体系。本文讨论的研究探讨了配体，阴离子和金属离子在阴离子-pi相互作用的背景下对基于四嗪的配体的超分子结构的微妙影响，以及它们在超分子结构的设计和合成中的重要性。计算研究突显了芳烃四极矩，分子极化率和取代基对阴离子-π相互作用强度的影响。然而，更重要的是，这项工作建立了多原子阴离子和N-杂环之间阴离子-pi相互作用固有的独特方向性，这可以用于指导超分子结构中的配体，最近Dunbar小组的工作证明了这一点。 bptz的金属环向CoII和FeII的延伸证明了仅通过改变金属离子即可调节金属环腔尺寸的能力，并导致了两个[SbF6]-的惊人包封[Fe5（bptz）5（NCCH3）10] [SbF6] 10中的阴离子。 1H NMR光谱和电化学研究表明，方形和五边形金属环具有微弱但显着的差异，并支持溶液中阴离子-π相互作用的存在，并突出了包封的阴离子在金属环的模板化和稳定性中的重要性。首次通过1H NMR研究了方形和五边形金属环之间的相互转化。增加螯合配体的pi-酸度从bptz到bmtz导致仅将一个[SbF6]-阴离子包封在[Fe5（ bmtz）5（NCCH3）10] [SbF6] 10，尽管紧密配合，但最大程度地提高了与配体的阴离子-π相互作用。通过开发从钠盐和Fe4Cl8（THF）6阴离子中提取多种阴离子的[Fe（NCCH3）6] 2+盐的新合成方案，克服了将不同阴离子引入金属环结构的重大障碍。此外，通过与已知的FeII金属环化合物溶液行为进行比较，通过MS，电化学和1H NMR实验的组合，确定了较不稳定的[Fe5（bptz）5（NCCH3）10] [PF6] 10金属环的核。

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    Giles Ian;

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  • 年度 2012
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