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hanks2010

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wu

[交流] 求教关于柠檬酸与金属离子的络合

举个例子吧:

将Rh(NO3)3溶液和柠檬酸溶液混合搅拌,柠檬酸和Rh离子间形成的络合物是什么形式?
此外,还有像Ce(NO3)3或者ZrO(NO3)2溶液和柠檬酸溶液混合后呢?

还有个问题,用什么方法可以将Pd(NO3)3或Rh(NO3)3中的金属阳离子转到类似氯铂酸根离子的阴离子里面去呢?

[ Last edited by hanks2010 on 2007-11-4 at 15:14 ]
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hanks2010

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wu

更简单一点问:与柠檬酸形成络合物后,在水溶液中,过度金属原子是否存在于阴离子根中呢,比如[Ce(C6H5O7)2]
4楼2007-11-05 19:54:51
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whasn204

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rabbit7708(金币+2,VIP+0):鼓励新虫应助喽,欢迎常来催化版!:)
nxl5096224(金币+2,VIP+0):多谢应助咯~3Q!
I used the chelating reaction before. I can not answer your question completely this time. but I carefully searched literatures and found one example (De chelating) for you. Unfortunately it was an old literature (should be old!!). The abstract may provide some useful informaiton for you. See the following.  I think there is no big difference for  ion chelated citric acid, except numbers of ligand.

Complex cerium citrates.     Sil'nichenko, V. G.    Redkozem. Elementy, Akad. Nauk SSSR, Inst. Geokhim. i Analit. Khim  (1963),     145-8.  Journal  language unavailable.    CAN 61:23010    AN 1964:423010    CAPLUS  

Abstract

The complex formation of Ce(III) and Ce(IV) with Na citrate was investigated.  The prepn. of CeC6H5O7.3H2O (I), Na3[Ce(C6H5O7)2] .3H2O (II), and Na4[CeO(C6H5O7)2].3HO (III) is described.  The compds. were obtained through reaction of the corresponding stoichiometrical amts. of Ce(NO3)3 and Na3C6H5O7.  In these compds. the coordination no. of Ce (6) is satd. by 2 citric acid residues which are bound through the O atoms of the carboxyl groups.  Some Ce dicitrate complexes of the type M3[Ce(C6H5O7)2] (M = Na, K, NH4) were synthesized with different alkali metal in the outer coordination sphere.  Addn. of heavy metals solns. to the solns. of these complex dicitrates resulted in substitutions in the complex inner sphere leading to the formation of ppts. of low soly.  Particularly, addn. of Ce(III) soln. to the soln. of the Na dicitrate resulted in the pptn. of a compd. chem. characterized as CeC6H5O7 although it is assumed to be more probably an innersphere substitution product of the complex dicitrate whose formula Ce[Ce(C6H5O7)2] does not differ from that of the simple compd. from an anal. standpoint.  The compds. I, II, and III were submitted to differential thermal and thermogravimetric analysis which showed that the water of crystn. was lost smoothly without decompn. up to 200 for I and II, while the corresponding curve of III showed a sharp max. at 120 related to the transformation of Ce(IV) into Ce(III).

[ Last edited by whasn204 on 2007-11-5 at 19:30 ]
催化剂。
2楼2007-11-05 19:28:58
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daiqiguang

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rabbit7708(金币+2,VIP+0):多谢热心应助!:)
nxl5096224(金币+2,VIP+0):多谢应助~
可以看看下文

[ Last edited by daiqiguang on 2007-11-5 at 19:34 ]
有事请到www.chemj.cn上找chemj,谢谢
3楼2007-11-05 19:33:31
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whasn204

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nxl5096224(金币+2,VIP+0):多谢应助啦~
引用回帖:
Originally posted by hanks2010 at 2007-11-05 19:54:51:
更简单一点问:与柠檬酸形成络合物后,在水溶液中,过度金属原子是否存在于阴离子根中呢,比如[Ce(C6H5O7)2]

是的。
柠檬酸是一种常见的chelating agent,另外还有一个叫EDTA. 它们络和的机理很类似,均是通过N, 或 O电负性较强的阴离子作用于阳离子中心,形成的是一个复合物,结构相对稳定。

Wiki有这样一个解释:
The ligand forms a chelate complex with the substrate. The term is reserved for complexes in which the metal ion is bound to two or more atoms of the chelating agent, although the bonds may be any combination of coordination or ionic bonds.

如果想了解更多,可以参看这个条目: http://en.wikipedia.org/wiki/Chelating_agent
催化剂。
5楼2007-11-06 14:02:19
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