Spectra, equilibrium and photoredox chemistry of iodobismuthate(III) complexes in acetonitrile
Spectra, equilibrium and photoredox chemistry of iodobismuthate(III) complexes in acetonitrile
复制标题
DOI：
10.1016/s0020-1693(00)00090-6
复制
发表时间：
2000-06-30
影响因子：
2.8
通讯作者：
Mikó, I
中科院分区：
文献类型：
--
作者：
Horváth, O;Mikó, I
在乙腈中测定了BH_（4-）、Bi_（63-）、Bi_（74-）配合物的吸收光谱和逐步形成常数（K-4 = 1.5 +/- 0.3 x 10（5）dm（3）mol（-1），K-6 = 1.3 +/- 0.2 x 10（7）dm（6）mol（-2），K-7 = 160 +/- 20 dm（3）mol（-1））。这些络合物在溶液中的光解导致形成Bi（II）和I-。或I-2（.-）作为初级产品。该反应在355 nm激发下的量子产率分别为0.057 +/- 0.005和0.038 +/- 0.004的四和七碘铋（III）配合物。整个反应的效率（以I-3（-）或I-2作为最终产物的形成）也取决于实际配位数、照射波长和Bi（III）的浓度。总的量子产率基本上由初级产物的竞争性暗反应决定。在脱气系统中，二碘物质（I-2（.-））起着更重要的作用;该机制中的一个关键步骤是I-2（.-）和基态铋（III）络合物。在空气饱和溶液中，Bi（II）中间体的氧化导致过氧化物的形成，是影响最终效率的关键反应。(C)2000 Elsevier Science S.A. All rights reserved.
The individual absorption spectra and the stepwise formation constants of the kinetically labile BH4-, BiI63-, BiI74- complexes were determined in acetonitrile (K-4 = 1.5 +/- 0.3 x 10(5) dm(3) mol(-1), K-6 = 1.3 +/- 0.2 x 10(7) dm(6) mol(-2), K-7 = 160 +/- 20 dm(3) mol(-1)). Photolysis of these complexes in solution results in the formation of Bi(II) and I-. or I-2(.-) as primary products. The quantum yields of this reaction at 355-nm excitation are 0.057 +/- 0.005 and 0.038 +/- 0.004 for the tetra- and heptaiodobismuthate(III) complexes, respectively. The efficiency of the overall reaction (with the formation of I-3(-) or I-2 as end products) also depended on the actual coordination number, the irradiation wavelength and the concentration of Bi(III) as well. The overall quantum yield is essentially determined by the competitive dark reactions of the primary products. In deaerated systems, the diiodide species (I-2(.-)) plays a more important role; one key step in the mechanism is the reaction between I-2(.-) and the ground-state bismuth(III) complexes. In air-saturated solutions, the oxidation of the Bi(II) intermediate, leading to the formation of peroxide, is the crucial reaction affecting the final efficiency. (C) 2000 Elsevier Science S.A. All rights reserved.