2002 Fiscal Year Final Research Report Summary
Binding interactions between transition metal cations and organic molecules
| Project/Area Number |
13640540
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Organic chemistry
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| Research Institution | Kyushu University |
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Principal Investigator |
MISHIMA Masaaki Kyushu University, Inst.for Fundamental Research of Organic Chemistry, Associate Professor., 有機化学基礎研究センター, 助教授 (20037279)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Copper cation basicity / Lithium cation basicity / Proton affinity / Pyridines / Acetophenones / Binding energy / Gaseous ion-molecule reaction / FT-ICR |
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| Research Abstract |
To elucidate the intrinsic nature of interaction between transition metal cation and organic molecule structural effects on the binding energy was investigated. The free energy changes for the reaction CuL_2^+ = Cu^+ + 2L were obtained in the gas phase for a series of acetophenones and pyridines by measuring ligand exchange equilibria using a FT-ICR mass spectrometer. For comparison lithium cation basicities in which electrostatic interaction plays a important role were also determined for acetophenone series in this sudy.
Analysis of substituent effects on gas-phase basicity toward Cu cation, GB(Cu), showed that the effect of para-π-donor substituents on the GB(Cu) of acetophenone is reduced by 29% than that of GB(H) while that of GB(Li) is reduced by 37%. The magnitude of substituent effects on GB(Cu) is smaller than the corresponding GB(H) by 38% but is larger than the GB(Li). The similar results were observed for the pyridine bases. These results suggest that the positive charge developed at the carbonyl oxygen atom in the Cu-complex ion is larger than that of Li-complex ion.
Reaction of Cu and Li cations with a series of MeO(CH_2)_nOMe that has two binding sites was studied in the gas phase. Cu cation gave a 1 : 1 adduct ion when n is larger than 4. The GB(Cu) increased with n, i.e., 10 kcal/mol from n=4 to n=9. On the other hand, although a 1 : 1 adduct ion with Li cation was observed when n=2, the change of GB(Li) is much smaller than the GB(Cu). This result suggests that the linearity of the O-Cu-O bond is an important factor to determine the GB(Cu), being in consistent with the optimized geometries obtained by DFT calculations.
These facts suggests that the nature of O-Cu and N-Cu bonds are controlled by covalent interactions in addition to electrostatic interactions.
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Research Products
(18 results)
