A series of new Fe(II) coordination polymers based-on [Hg(XCN)3]− or [Hg(XCN)4]2− (X = S, Se) building blocks: Synthesis, crystal structure and magnetic property

Self-assembly of the tetrahedral metalloligand building block [(Hg II (XCN) 4 ] 2- , where X = S or Se, a series of bis-monodentate pyridine-like ligands and iron(II) compounds has afforded seven new heterobimetallic Hg II –Fe II coordination polymers. Single crystal X-ray diffraction structural analysis revealed the infinite two-dimensional (2D) sheet with different topologies for all the complexes except 3 , which belonged to inherent 3D-structure. The results of the temperature dependent magnetic susceptibility investigation over all the complexes discovered the paramagnetic behavior for the high spin iron(II) ion in all the complexes within the temperature range of 2–300K, except complex 6 . The thermo- and photomagnetic property study for complex 6 showed incomplete spin crossover (SCO) behaviors with interesting thermomagnetic properties and light-induced excited spin state trapping effect (LIESST). The results show that the ligand field, configurations, rigidity, and polarity of the bridging ligands, as well as the coordination mode with the Fe(II) ion of the building units, are important for the design and synthesis of the targeted coordination polymers. A serials of new non-Hoffman type of Fe(II) coordination polymers based-on [Hg(XCN) 3 ] − or [Hg(XCN) 4 ] 2− (X = S, Se) building blocks: synthesis, crystal structure and magnetic property. As has been known, spin-crossover (SCO) compounds, as one of the best-known magnetic materials with distinctive characteristics including thermochromism, controlled switching between high spin and low-spin, conductivity et al., have been paid special attention in molecule magnetism field because of their great potential as information storage material, sensor applications, photo-magnetic devices. Among which, the Hoffman type SCO compounds has been always hot research topic in molecular magnetic field due to their interesting SCO properties and structures since 1996. In order to find new types of hetero-bimetallic coordination polymers with interesting SCO properties but structurally different from the Hofmann-type, namely breakthrough the traditional topological structure type, the tetrahedral [Hg(S/SeCN) 4 ] 2- as metalloligand has been firstly introduced into SCO field by our group and obtained several SCO materials with intriguing magnetic property but with no general Hoffman-type structure. With the aim to further enrich and shed light on these types of non-Hoffman like compounds, we focus on preparation of new heterobimetallic SCO coordination polymers with different Hoffman structures in this paper. The different structural types and magnetic properties for the here reported complexes will be helpful for further targeted assembling non-traditional Hoffman type SCO molecular magnetic material. The tetrahedral [Hg(S/SeCN) 4 ] 2- as metalloligand has been firstly introduced into SCO field by our group and seven SCO materials with intriguing magnetic property but with no general Hoffman-type structure have been synthesized. The results of thermo- and photomagnetic property study showed the occurrence of the temperature dependent gradual incomplete spin crossover (SCO) property and light-induced excited spin state trapping effect (LIESST). The coordination field, configurations, rigidity, and polarity of the bridging ligands, as well as the of coordination mode toward the Fe(II) ion of the building units, play important roles on the structure and properties of the target non-Hoffmann-type coordination polymers.