2005 Fiscal Year Final Research Report Summary
Development of Novel Reactions in Cluster-Mediated Anion Chemistry
| Project/Area Number |
15350006
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | The University of Tokyo |
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Principal Investigator |
NAGATA Takashi The University of Tokyo, Graduate School of Arts and Sciences, Professor, 大学院・総合文化研究科, 教授 (10164211)
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| Co-Investigator(Kenkyū-buntansha) |
INOKUCHI Yoshiya Hiroshima University, Graduate School of Science, Associate Professor, 理学研究科, 助教授 (30311187)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Molecular cluster anion / Anion chemistry / Microflask / Entrainer effect / Nonadiabatic dynamics / Ab initio calculation |
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| Research Abstract |
The aim of this research project was the development of novel gas-phase reactions, which can be categorized as "cluster-mediated" anion chemistry, by exploiting unique properties of molecular cluster anions, such as floppiness of their structures, affinity for an excess electron and propensity for molecular uptake. The results are summarized as follows:
1.The anion radical of carbon dioxide, CO_2^<・->, sustained on a surface of gas-phase (H_2O)_n was found to behave as a carboxylation reagent for alkyl halides (RX), presenting a sharp contrast to the reactions of CO_2^<・->in solutions, where the interaction of CO_2^<・->with RX leads to the formation of X-through dissociative electron transfer. The (H_2O)_n,"microflask" acts not only as a sustainer of the unstable CO_2^<・->reagent but also as a stabilizer of the product anions.
2.Radical addition reactions of CO_2^<・->against NO, O_2 and conjugated alkenes were observed in the (CO_2)_n^- microflask. Those reactions in (CO_2)_n^- are to be categorized as a one-step carboxylation process by the reductive activation of CO_2 within the microflask.
3.The geometrical and electronic properties of [(CO_2)_n(H_2O)_m]^- as a microflask of binary components were investigated by ab initio calculations at the MP2/6-311++G(d, p) level. The number of isomeric forms determined for n = 1-4 and m = 1, 2 amounts to 117 in total, providing information on the stabilization mechanism for [(CO_2)_n(H_2O)_m]^-.
4.The selective stabilization of CO_2^<・-> by entrainer molecules in [(CO_2)_n(H_2O)_m]^- with n 【greater than or equal】4 was revealed by the measurement of infrared photodissociation spectra of [(CO_2)_n(H_2O)_m]^- in the 2800-3800 cm^<-1> region.
5.Photodissociation of the gas-phase triiodide anion and its complexes, I_3^- and I_3^-(H_2O)_m, was investigated using photofragment TOF mass spectrometry, which leads to the detailed understanding of the nonadiabatic dissociation dynamics and the solvent effects on the product branching.
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