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鉍(Ⅲ)与流氰离子在酸性溶液中形成粽黄色络合物这一事实已久为人知,并已用于鉍之比色测定。从对该体系的已有研究看,鉍(Ⅲ)与硫氰离子可形成配位数从1到6的六种单核络合物。最近还有制备K_2Bi(SCN)_5与K_3Bi(SCN)_6晶体的报导。但对这一体系的研究并不充分,不同作者所得的稳定常数甚为悬殊。很难用离子强度、温度等实验条件的差别予以解释。而各级络合物的摩尔消光系数则尚未见报导。因此我们用
The fact that bismuth (III) and cyanide ions form a yellow complex in the acidic solution has long been known and has been used for the colorimetric determination of bismuth. From the previous studies on this system, bismuth (Ⅲ) and thiocyanate ions can form six kinds of mononuclear complexes with coordination number from 1 to 6. Recently there are reports on the preparation of K_2Bi (SCN) _5 and K_3Bi (SCN) _6 crystals. However, the research on this system is not sufficient, and the stability constants obtained by different authors are very different. It is difficult to explain the differences in experimental conditions such as ionic strength and temperature. The molar extinction coefficients of the complexes at all levels have not been reported yet. So we use