Crystal structures of [M(NTf2)3(H2O)n] (M = Eu and Yb) and a template effect of linear molecules on the 3D hydrogen bonding network structure of [Eu(NTf2)3(H2O)3]

Lewis acid catalysts [Eu(NTf2)3] and [Yb(NTf2)3] can be easily crystallized from a p-xylene solution in the presence of carboxylic acids and a small amount of water to give a trihydrate and a pentahydrate, respectively. In the crystallization of [Eu(NTf2)3(H2O)3], linear molecules such as n-alkanes and n  -alkanoic acids act as templates to form crystals belonging to the trigonal space group P3¯ with a hexagonal cylindrical structure, which is constructed by 3D hydrogen bonding network. On the other hand, [Eu(NTf2)3(H2O)3] crystallized in the cubic space group P213 in the presence of a bulkier carboxylic acid, cyclohexanecarboxylic acid. In both [Eu(NTf2)3(H2O)3] crystals, NTf2- ligands act as bidentate ligands coordinating to the Eu atom through two oxygen atoms. [Yb(NTf2)3] crystallized as a pentahydrate in the monoclinic space group P21/n  , in which NTf2- ligands coordinated to the Yb atom with only one oxygen atom.

Graphical abstract[Eu(NTf2)3] and [Yb(NTf2)3] can be easily crystallized from a p-xylene solution in the presence of carboxylic acids and a small amount of water to give a trihydrate and a pentahydrate, respectively. In the crystallization of [Eu(NTf2)3], a unique template effect of n-alkanes and n-alkanoic acids was observed to form a hexagonal cylindrical structure through 3D-hydrogen-bonding network.Figure optionsDownload full-size imageDownload as PowerPoint slide