Correlation between Solution and the Solid State: The pH Dependent Composition in the Ternary System [Co(H2O)6]2+ or [Ni(H2O)6]2+/Piperazine/Phosphate
作者:Emma Craven、Khalid Abu-Shandi、Christoph Janiak
DOI:10.1002/zaac.200390031
日期:2003.2
selected pH values to isolate desired species from the known solution composition. Crystallization afforded [M(H2O)6]2+(C4H12N22+)(HPO42—)2 at pH 3.5 and 6.2 (M = Co, Ni), and Co3(PO4)2·8H2O at pH 10.5. No crystals with the dihydrogenphosphate anion or a metal-bound piperazine ligand could be isolated under the reaction conditions. The solid-state assembly in the isomorphous structures of [M(H2O)6](C4H12N2)(HPO4)2
哌嗪 (C4H10N2) 和磷酸盐在氯化钴或镍或硝酸盐存在下通过电位滴定在 pH 2 和 8 之间进行了研究。电位滴定表明存在 [M2+(H2O)5(C4H11N2+)]3+和 [M2+(H2O)5(C4H10N2)]2+ 在溶液中,M = Co 的稳定性常数 logK 分别为 3.1 和 3.8,M = Ni 的稳定性常数 logK 分别为 3.1 和 3.6。然后在选定的 pH 值下进行结晶实验以从已知的溶液组合物中分离所需的物质。结晶得到 [M(H2O)6]2+(C4H12N22+)(HPO42-)2 在 pH 3.5 和 6.2 (M = Co, Ni) 和 Co3(PO4)2·8H2O 在 pH 10.5。在反应条件下不能分离出具有磷酸二氢根阴离子或金属结合的哌嗪配体的晶体。