1999 Fiscal Year Final Research Report Summary
New development of analytical chemistry with the use of molybdate as a reactive reagent
| Project/Area Number |
10640594
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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 |
分離・精製・検出法
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| Research Institution | Kobe University |
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Principal Investigator |
HIMENO Sadayuki Kobe University, Faculty of Science, Professor, 理学部, 教授 (30031363)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Analytical Chemistry / Molybdate / Polyoxometalate |
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| Research Abstract |
Polyoxomolybdate complexes with the Anderson structure have been prepared so far by boiling a reaction mixture of Mo(VI) and heteroions at very high concentrations. However, the existence in solution remains to be confirmed. Our spectrophotometric studies have revealed that a series of Anderson complexes are formed and stable at very low concentrations of Mo(VI) and heteroions in aqueous solution, and the complex-formation reaction proceeds very rapidly even at room temperature. On the basis of these findings, a sensitive method was developed for the capillary electrophoretic determination of various oxoanions with 6-coordinated structures. Besides, the complex-formation reaction was applied to the oxidation-state analysis of Cr(III) and Cr(VI), and of I(V) and I(VII).
In aqueous-organic mixed media, we have found that Mo(VI) can react oxoanions with 3-coordinated structures including P(III), Se(IV) and Te(IV) to form 15-molybdo- and 12-molybd-complexes and crystallographic structure of the 12-molybdo-2-phosphonate complex has been determined. In addition, we have found that 12-tungstophosphate with the β-Keggin structure is stabilized by the presence of acetonitrile in the reaction mixture of Mo(VI) and P(V), being isolated as the tetraalkylammonium salt. It turned out that the new β-isomer underwent two-electron reductions in acidified organic media including acetone and acetonitrile. In aqueous-acetonitrile mixed media, the 12-molybdogallate complex with the Keggin structure was formed by the reaction of Mo(VI) and Ga(III), whereas the so-called Anderson complex was formed in aqueous solution. The formation of the Keggin complex was applied to the voltammetric determination of Ga(III).
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