层状双氢氧化物的稳定性。2. 直接从溶液中形成含Cr(III)的层状双氢氧化物。
Layered double hydroxide stability. 2. Formation of Cr(III)-containing layered double hydroxides directly from solution.
作者信息
Boclair J W, Braterman P S, Jiang J, Lou S, Yarberry F
机构信息
Department of Chemistry, University of North Texas, Denton 76203-5070, USA.
出版信息
Chem Mater. 1999;11(2):303-7. doi: 10.1021/cm980524m.
Solutions containing divalent metal [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+] chlorides and CrCl3 6H2O were titrated with NaOH to yield, for M(II) = Zn, Co, and Ni, hydrotalcite-like layered double hydroxides (LDHs), [[M(II)]1-z[Cr(III)]z(OH)2][Cl]z yH2O, in a single step, without intermediate formation of chromium hydroxide. Analysis of the resultant titration curves yields solubility constants for these compounds. These are in the order Zn < Ni approximately Co, with a clear preference for formation of the phase with z = 1/3. With Mg2+ as chloride, titration gives a mixture of Cr(OH)3 and Mg(OH)2, but the metal sulfates give Mg2Cr(OH)6 1/2(SO4) by a two-step process. Titrimetric and spectroscopic evidence suggests short-range cation order in the one-step LDH systems.
含有二价金属氯化物[M(II) = Mg2+、Zn2+、Co2+、Ni2+、Mn2+]和六水合三氯化铬（CrCl3·6H2O）的溶液用氢氧化钠进行滴定，对于M(II)为Zn、Co和Ni的情况，可一步生成类水滑石层状双氢氧化物（LDHs），即[[M(II)]1-z[Cr(III)]z(OH)2][Cl]z·yH2O，不会中间形成氢氧化铬。对所得滴定曲线的分析得出了这些化合物的溶解度常数。其顺序为Zn < Ni ≈ Co，明显倾向于形成z = 1/3的相。以Mg2+作为氯化物进行滴定时，会得到氢氧化铬和氢氧化镁的混合物，但金属硫酸盐通过两步过程生成Mg2Cr(OH)6·1/2(SO4)。滴定法和光谱学证据表明一步法LDH体系中存在短程阳离子有序排列。
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