Crystal-to-crystal transformations in heterometallic yttrium(III)-copper(I) iodide derivatives in a confined solvent-free environment: Influence of solvated yttrium cations on the nuclearity and dimensionality of iodocuprate clusters
Résumé
The solvated yttrium iodide precursors [Y(L)(8)]I-3 (L = DMSO or DMF), prepared in situ by stirring YI3(PrOH)(4) in DMSO or DMF, react with CuI in the presence of NH4I to give ionic hetero-metallic species [Y(DMSO)(8)][Cu-2(mu-I)I-4] (1) and [Y(DMF)(8)][Cu-4(mu(3)-I)(mu(3)-I)(3)I-2] (2) in excellent yields. Re-crystallization of 1 from DMF afforded the mixed-solvate complex [Y(DMSO)(6)(DMF)(2)][CuI3][I] (3). Compounds 2 and 3 undergo unique crystal-to-crystal transformation via progressive substitution of DMF by water molecules in a confined, solvent-free environment. Thus, crystals of 3 transform into [Y(DMSO)(6)(H2O)(2)][CuI3][I](4), whereas a discrete ion-pair assembly of 2 is first converted into a 1-D zig-zag structure [Y(DMF)(6)(H2O)(2)](3+)[Cu-7(mu(4)-I)(3)(mu(3)-I)(2)(mu-I)(4)(I)]infinit y(3-) (5) and finally into a 2-D sheet containing mixed-valent copper atoms, [Y(DMF)(6)(H2O)(3)](3+)[(Cu7Cu2II)-Cu-I(mu(3)-I)(8)(mu-I)(6)](2 infinity)(3-) (6). The bi- and tetrafurcate H-bonding between water ligands on yttrium and iodides of the Cu-I cluster plays a pivotal role in the evolution of structures 4-6. Formation of a wide range of iodocuprate structures in 1-6, from discrete mono-, di- or tetranuclear units to one- and two-dimensional extended arrays, reflects the influence of solvated yttrium cations on the nuclearity and dimensionality of Cu-I clusters. TG-DTA-MS studies and DFT calculations for these complexes have also been carried out in order to determine their thermal stability and have insight about aforesaid transformations.