反芳香族B,N-カルベンσ配位子の開発と常磁性/アニオン性金錯体の合成と物性解明

共轭π体系的芳香性和抗芳香性的相互作用是在设计功能分子时调节光引发电子转移性质的重要设计策略。对于过渡金属(TM)光催化剂，虽然杂环芳香族配体被广泛用于调节其(光)氧化还原行为，但由于缺乏合成方法，抗芳香族配体的作用仍然知之甚少。本项目提出了一种分离含4-π-B，N-杂环卡宾(BNC)的自由基和阴离子金络合物的设计和合成方法。BNC具有良好的抗芳香性和对硼原子的包合作用，使其具有较强的π接受能力和σ供体能力，是稳定和调节金属异常氧化态和自由基行为的理想材料。通过锂对(BNC-Cl)AUL络合物的2E还原，可以分离出亮橙色的金酸锂络合物Li[(BNC)AUL]。计算分析表明，尽管有4π的电子计数，但由于定域的BNπ键，Au(I)上的中性BnC配体大多是非芳香族的。还原后，金中心仍为+i，而BnC部分为6π芳香体系。特别是，连接碳中心的p轨道与Au(I)6p轨道有很强的相互作用，相互作用能在15.5kcal/mol之间。这一结果表明，金(I)可以通过6p轨道而不是5d轨道与配体形成多个键。

The interplay of aromaticity and antiaromaticity of conjugated π systems is a crucial design strategy for tuning light-initiated electron-transfer properties in designing functional molecules. For transition metal (TM) photocatalysts, while heterocyclic aromatic ligands are widely used for modulation of their (photo)redox behaviors, the effect of antiaromatic ligands remains poorly understood due to a lack of synthetic methodologies. This project proposed a design and synthesis to isolate radical and anionic gold complexes bearing a 4π B, N-heterocyclic Carbene (BNC). The expected antiaromaticity and the inclusion of boron atoms in BNC results in its super π-accepting and σ-donating abilities which are ideal to stabilize and tune unusual oxidation states and radical behaviors of the metal.The synthesis of several derivatives of BNC Au(I) complexes were established. A 2e reduction of the (BNC-Cl)AuL complex by lithium allowed isolation of a bright orange lithium aurate complex Li[(BNC)AuL]. Computational analysis indicated that, despite of the 4π electron counting, the neutral BNC ligand on Au(I) is mostly non-aromatic in character, due to the localized BN π bonds. After reduction, the gold center remained as +I, whereas the BNC moiety became a 6π aromatic system. In particular, the occupied p orbital at the ligating carbon center was shown to interact strongly with the Au(I) 6p orbital with an interaction energy between 15.5 kcal/mol. This result showed that the gold(I) can form multiple bonds with ligand through its 6p orbital ligands instead of 5d orbitals.