Husson Ch., Delangle P., Pécaut J., Vottéro Ph. J. A.
Laboratoire de Reconnaissance Ionique and Laboratoire de Chimie de Coordination, Service de Chimie Inorganique et Biologique, Département de Recherche Fondamentale sur la Matière Condensée, CEA-Grenoble 17, Rue des Martyrs, F-38054 Grenoble Cedex 9, France.
Inorg Chem. 1999 May 3;38(9):2012-2019. doi: 10.1021/ic980924b.
cis,cis-1,3,5-Trihydroxycyclohexane (L(1)()) and cis,cis-1,2,3-trihydroxycyclohexane (L(2)()) have been considered as ligands for the complexation of europium(III) in organic solvents. Three complexes were prepared and characterized by X-ray diffraction analysis, microanalysis, electrospray mass spectrometry, and proton NMR. Depending on the europium(III)-to-ligand ratio, ML or ML(2) complexes were formed in organic solution. Complexes formed with ligand L(2)() are stable in methanol solution, while those obtained from L(1)() are stable only in nonprotic solvents. This difference is related to the amount of energy involved in the necessary chair-chair conversion prior to complexation of the europium(III) ion. In the solid state the coordination sphere including in each case two L(1)()or L(2 )()molecules( )()as tridentate ligands, is completed by a bidentate nitrate anion and one molecule of water in 1, Eu(L(1))(2)(NO(3))(H(2)O)(2), two monodentate triflate anions and one molecule of water in 2, Eu(L(1))(2)(OTf)(2)(H(2)O), and a bidentate and a monodentate nitrate anion in 3, Eu(L(2))(2)(NO(3))(2). Many strong H bonds are present in the crystalline network with H.O distances between 1.77 and 2.301 Å. Proton NMR studies have shown that a moderate lowering of the temperature is sufficient to observe the different species present in solution, the proportions of which depend on the metal-to-ligand ratio. Conductometric studies have also provided indication about the number of coordinated anion in methanol and acetonitrile solutions.
顺式，顺式 -1,3,5 - 三羟基环己烷（L(1)()）和顺式，顺式 -1,2,3 - 三羟基环己烷（L(2)()）被视为在有机溶剂中与铕（III）络合的配体。制备了三种配合物，并通过X射线衍射分析、微量分析、电喷雾质谱和质子核磁共振进行了表征。根据铕（III）与配体的比例，在有机溶液中形成了ML或ML(2)配合物。与配体L(2)()形成的配合物在甲醇溶液中稳定，而由L(1)()得到的配合物仅在非质子溶剂中稳定。这种差异与铕（III）离子络合之前所需的椅式 - 椅式转化所涉及的能量量有关。在固态中，配位球在每种情况下都包括两个作为三齿配体的L(1)()或L(2 )()分子( )()，在1中由一个双齿硝酸根阴离子和一个水分子Eu(L(1))(2)(NO(3))(H(2)O)(2)完成，在2中由两个单齿三氟甲磺酸根阴离子和一个水分子Eu(L(1))(2)(OTf)(2)(H(2)O)完成，在3中由一个双齿和一个单齿硝酸根阴离子Eu(L(2))(2)(NO(3))(2)完成。在晶体网络中存在许多强氢键，H.O距离在1.77和2.301 Å之间。质子核磁共振研究表明，适度降低温度足以观察到溶液中存在的不同物种，其比例取决于金属与配体的比例。电导研究也提供了关于甲醇和乙腈溶液中配位阴离子数量的指示。
