Yttrium thiocyanate-based supramolecular architectures: Synthesis, crystal structures, and thermal properties

The reaction of [Y(H2O)5(NCS)3]·H2O (1) with crown ether (18-crown-6) and KNCS in methanol afforded the complexes [Y(H2O)4(NCS)3]·1.5(18-crown-6) (2) and [K(18-crown-6)(H2O)1.25]2n{[K(18-crown-6)]2[Y(NCS)6]}n·n(NCS) (3). In mononuclear complex 1, yttrium has a coordination number 8 and forms the coordination unit YO5N3. Complexes 1 are linked by hydrogen bonds to form a framework. The crystal structure of 2 contains the centrosymmetric ensembles [Y(H2O)4(NCS)3]2(18-crown-6)3 formed via hydrogen bonds. In the crystal structure of 3, the [Y(NCS)6]3− anions and the [K(18-crown-6)]+ cations form one-dimensional polymeric chains (-Y-NCS-K-)n. The thermal behavior of compounds 1 and 2 was investigated. It was shown that the supramolecular assembly has an effect on the temperature range for the removal of coordinated water molecules from the thiocyanate complex. The oxidative decomposition of the acido ligands in 1 and 2 occurs in a similar way to give Y2O2SO4 as the final product (700 °С).

Graphical abstractThe reaction of [Y(H2O)5(NCS)3]·H2O (1) with crown ether (18-crown-6) and KNCS in methanol afforded the complexes [Y(H2O)4(NCS)3]·1.5(18-crown-6) (2) and [K(18-crown-6)(H2O)1.25]2n{[K(18-crown-6)]2[Y(NCS)6]}n·n(NCS) (3). The crystal structure of 2 contains the centrosymmetric ensembles [Y(H2O)4(NCS)3]2(18-crown-6)3 formed via hydrogen bonds. In the crystal structure of 3, the [Y(NCS)6]3− anions and the [K(18-crown-6)]+ cations form one-dimensional polymeric chains (-Y-NCS-K-)n. It was shown that the supramolecular assembly has an effect on the temperature range for the removal of coordinated water molecules from the thiocyanate complex. The oxidative decomposition of the acido ligands in 1 and 2 occurs in a similar way to give (YO)2(SO4) as the final product (700 °С).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Complexes 1–4 has been synthesized and structurally characterized. ► In complex 1, yttrium has a coordination number 8, in 2–7, and in 3 and 4–6. ► The low temperature interval (65–103 °С) for removal of water from 2 is established.