2021 Fiscal Year Research-status Report
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
| Project/Area Number |
21K05099
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| Research Institution | Hiroshima University |
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Principal Investigator |
SHANG RONG 広島大学, 先進理工系科学研究科(理), 助教 (70754216)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | Aurate / Carbene / boron / redox active ligand |
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| Outline of Annual Research Achievements |
Stabilization of low oxidation gold anions as aurate or auride by organic ligands has long been a synthetic challenge, owing to the proneness for low-valent gold centers to cluster. Stabilization of highly-reduced gold complexes by π-modulating redox active ligand has only been achieved by cyclic (amino)(alkyl)carbene (CAAC). This work reports a simple modular synthesis of a boron, nitrogen-containing heterocyclic carbene (ClBNC) at a gold(I) center. These complexes showed a highly π-withdrawing character in the neutral 4π B,N-heterocyclic carbene (BNC) moiety and its reduced form showed π-donating properties to the gold(I) fragment, showcasing the first cyclic carbene ligand that allows electronic tunability between π-withdrawing and π-donating properties.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The complexation chemistry of the (tri-tert-butyl)azadiboriridine with gold(I) complexes, Au(L)Cl yielded borylgold(I)borane and borenium boryl-aurate complexes, which reacted with CNtBu to form a boron-containing heterocyclic (bora)iminyl ligand (ClBNC) in high-yields. Overall, the ClBNC ligand in neutral [(ClBNC)Au(PMe3)] complexes features a highly π-withdrawing carbene center while carrying a negative charge from borate moiety. Its ability to adopt both π-withdrawing and π-donating properties through redox chemistry makes them a great candidate for modulate the electronic states of the coordinated metal fragment, allowing the isolation of the first carbene-aurate complex.
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| Strategy for Future Research Activity |
The isolation of the 2-electron reduction product lithium aurate revealed our anticipated strategy for π-modulation is successful. In the future, three aspects will be pursued to further explore the potential of main-group π-modulating ligands to redox properties of transition metal complexes. Firstly, we will expand the reduction chemistry to amino- and Mesityl-derivatives. Their neutral (ClBNC)AuL precursors have been successfully obtained. Secondly, we are extending similar concept to diboron-phosphide (BNP) ligand. With two more electron at phosphine atom, it is a π-donor in contrast to current π-accepting BNC carbene ligands. Its oxidation will be investigated. Lastly, we are also extending this to all carbon multi-dentate ligands.
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| Causes of Carryover |
Due to COVID restrictions on traveling and remote work, part of budget could not be used. This will be used in purchases of chemicals required for this project, renewal of laboratory equipments such as magnetic stirrers, glassware as well as international travel for further collaborations involved in this project.
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Research Products
(10 results)
