| Budget Amount *help |
¥4,200,000 (Direct Cost: ¥4,200,000)
Fiscal Year 1986: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1985: ¥3,400,000 (Direct Cost: ¥3,400,000)
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| Research Abstract |
The kinetics of ligand exchange reactions in various oxovanadium(IV) complexes, VOL_5^<2+>, where L = dmso (dimethyl sulfoxide), dma(N,N-dimethylacetoamide), dmf (N,N- diemthylfomamide), CH_3CN, and H_2O, by means of the high pressure NMR method. The first-order rate constant, k_<obsd>, were determined at various applied pressure and plots of k_<obsd> vs. pressure gave the volumes of activation <DELTA>V^<<thermodynamics>>. The values of <DELTA>V^<<thermodynamics>> for the ligands, dmso, dma, dmf, CH_3CN, and H_2O, are -13.1, -9.9, -6.7, -0.4 and +1.9 cm^3 mol^<-1>, respectively. It is interesting that the values of <DELTA>V^<<thermodynamics>> change with the exchanging ligands. This means that the mechanism is not the same in the ligand exchange of VO^<2+> complexes. The large negative values of <DELTA>V^<<thermodynamics>> for the exchange of dmso,dma and dmf suggest the associative interchange mechanism. On the other hand, the dissociative interchange mechanism seems operative for the exchange of H_2O in terms of the lightly positive value of <DELTA>V^<<thermodynamics>>.
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