Geminal dianionic complexes and their corresponding carbenoids for small molecule activation
The thesis describes the synthesis of metal carbenoids and their application towards small molecule activation and the catalytic reduction of CO2 with borane. Chapter 1 describes the synthesis of a novel unsymmetric phosphonium-stabilized methane ligand, the monoanionic and dianionic lithium and ma...
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| Format: | Thesis |
| Language: | English |
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2016
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| Online Access: | http://hdl.handle.net/10356/68863 |
| _version_ | 1811695240260616192 |
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| author | Ho, Samuel Ying Fu |
| author2 | So Cheuk Wai |
| author_facet | So Cheuk Wai Ho, Samuel Ying Fu |
| author_sort | Ho, Samuel Ying Fu |
| collection | NTU |
| description | The thesis describes the synthesis of metal carbenoids and their application towards small molecule activation and the catalytic reduction of CO2 with borane.
Chapter 1 describes the synthesis of a novel unsymmetric phosphonium-stabilized methane ligand, the monoanionic and dianionic lithium and magnesium derivatives. Their electronic structures were elucidated by X-ray crystallography and DFT calculations.
Chapter 2 reports the mild oxidation of the dianionic complexes, which underwent an unprecedented intramolecular B-H insertion with BH3 into the central carbon via a carbenoid species. In addition, the carbenoid Ph2P(S)C(Cl)P(S)Ph2Li, underwent a similar intermolecular B-H insertion with BH3. The mechanism of the B-H bond insertion was studied by NMR spectroscopy and DFT calculations, which shows the concerted bond breaking of a B-H and C-Cl bond and the bond forming of a Li-Cl and C-H bond. This accounts for the low energy required for the B-H insertion reaction. Moreover, the attempted isolation of the magnesium carbenoid intermediate was described.
The synthesis and reactivity of bis(iminophosphoranyl)carbenoid Ph2P(NMes)C(Cl)P(NMes)Ph2Li (Mes = 1,3,5-Me3C6H2 ) was presented in Chapter 3 and reacted with BH3 yielding the boronium species. ClC(PPh2NMes)2BH2, and LiBH4.
Chapter 4 describes the application of the boronium as one of the best catalyst for CO2 reduction by BH3. An intermediate ClC{PPh2NMes}2BH{OC(O)H} was isolated and a mechanism of this transformation was proposed.
Lastly, in chapter 5, the step wise synthesis of a novel unsymmetric carbenoid and its reactivity with BH3 was probed and showed a B-H insertion reaction. |
| first_indexed | 2024-10-01T07:20:19Z |
| format | Thesis |
| id | ntu-10356/68863 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T07:20:19Z |
| publishDate | 2016 |
| record_format | dspace |
| spelling | ntu-10356/688632023-02-28T23:53:45Z Geminal dianionic complexes and their corresponding carbenoids for small molecule activation Ho, Samuel Ying Fu So Cheuk Wai School of Physical and Mathematical Sciences Nicolas Mézailles DRNTU::Science::Chemistry::Inorganic chemistry::Synthesis The thesis describes the synthesis of metal carbenoids and their application towards small molecule activation and the catalytic reduction of CO2 with borane. Chapter 1 describes the synthesis of a novel unsymmetric phosphonium-stabilized methane ligand, the monoanionic and dianionic lithium and magnesium derivatives. Their electronic structures were elucidated by X-ray crystallography and DFT calculations. Chapter 2 reports the mild oxidation of the dianionic complexes, which underwent an unprecedented intramolecular B-H insertion with BH3 into the central carbon via a carbenoid species. In addition, the carbenoid Ph2P(S)C(Cl)P(S)Ph2Li, underwent a similar intermolecular B-H insertion with BH3. The mechanism of the B-H bond insertion was studied by NMR spectroscopy and DFT calculations, which shows the concerted bond breaking of a B-H and C-Cl bond and the bond forming of a Li-Cl and C-H bond. This accounts for the low energy required for the B-H insertion reaction. Moreover, the attempted isolation of the magnesium carbenoid intermediate was described. The synthesis and reactivity of bis(iminophosphoranyl)carbenoid Ph2P(NMes)C(Cl)P(NMes)Ph2Li (Mes = 1,3,5-Me3C6H2 ) was presented in Chapter 3 and reacted with BH3 yielding the boronium species. ClC(PPh2NMes)2BH2, and LiBH4. Chapter 4 describes the application of the boronium as one of the best catalyst for CO2 reduction by BH3. An intermediate ClC{PPh2NMes}2BH{OC(O)H} was isolated and a mechanism of this transformation was proposed. Lastly, in chapter 5, the step wise synthesis of a novel unsymmetric carbenoid and its reactivity with BH3 was probed and showed a B-H insertion reaction. Doctor of Philosophy (SPMS) 2016-06-15T04:16:02Z 2016-06-15T04:16:02Z 2016 Thesis http://hdl.handle.net/10356/68863 en 257 p. application/pdf |
| spellingShingle | DRNTU::Science::Chemistry::Inorganic chemistry::Synthesis Ho, Samuel Ying Fu Geminal dianionic complexes and their corresponding carbenoids for small molecule activation |
| title | Geminal dianionic complexes and their corresponding carbenoids for small molecule activation |
| title_full | Geminal dianionic complexes and their corresponding carbenoids for small molecule activation |
| title_fullStr | Geminal dianionic complexes and their corresponding carbenoids for small molecule activation |
| title_full_unstemmed | Geminal dianionic complexes and their corresponding carbenoids for small molecule activation |
| title_short | Geminal dianionic complexes and their corresponding carbenoids for small molecule activation |
| title_sort | geminal dianionic complexes and their corresponding carbenoids for small molecule activation |
| topic | DRNTU::Science::Chemistry::Inorganic chemistry::Synthesis |
| url | http://hdl.handle.net/10356/68863 |
| work_keys_str_mv | AT hosamuelyingfu geminaldianioniccomplexesandtheircorrespondingcarbenoidsforsmallmoleculeactivation |