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Two iso-structural two-dimensional (2D) porous coordination polymers, which formulated as [Fe(1,3-di(4-pyridyl)propane) 2 (NCX) 2 ] 2 (X = S [ 1 ], Se [ 2 ]) and featured 2-fold interpenetration, have been synthesised and characterized. Crystal structure, Hirshfeld surfaces analysis and magnetic properties of them were described. The basic-unit of 1 and 2 was the 2D rhombic grids [2 × (4, 4)] network, and the intermolecular interactions in the crystals were dominated by C–H…π, H–H and C–H…S (Se) contacts. The stronger ligand field strength of SeCN − than that of SCN − resulted to different magnetic properties: compound 1 shows paramagnetic property while 2 display displays an incomplete SCO transition approximately 30% conversion of high-spin (HS) to low-spin iron(II) sites with transition temperature of 100 K. [ABSTRACT FROM AUTHOR]

Guest molecule dependent crystal structures, intermolecular interactions and magnetic properties of an iron (II) coordination polymer ( 2 ) with 4,4′-dipyridyl disulfide (4-DPS) ligand have been investigated. Polymer 2 {[Fe(NCS) 2 (4-PDS) 2 ]·2(2,5-DCP)} n was derived from polymer 1 [Fe(NCS) 2 (4-PDS) 2 ·4H 2 O] n through the change of water molecules by 2,5-dichloropyrazine molecules (2,5-DCP). This substitution leads to the change of the polymer motif from di -triangle to rectangle, and the decrease of longer contacts (S–H, N–H, C–H and H–H) while increase of the π ⋯ π (C–C) contacts in the crystal. These above changes then tuned the electronic structure of the iron (II) ion from high spin (HS) state ( 1 ) to the onset high spin (HS)–low spin (LS) transition ( 2 ), and resulted intermolecular anti-ferromagnetic interactions at lower temperatures. [ABSTRACT FROM AUTHOR]

Two new mononuclear iron (II) coordination complexes: Fe(L1)2(SCN)2(1, L1:5-dimethylether-4-(4-methylphenyl)-3-(2-pyridinyl)-1,2,4-triazole) and Fe(L2)3(ClO4)2(2, L2:1-ethyl acetate-2-(2-pyridinyl)-imidazole), for the exploration of spin-crossover compounds have been synthesized and characterized. Structural analysis revealed that the framework of complex1is featured with 1-D chain structure connected by weak π···π interactions between the adjacent L1ligands, while complex2featured with various kinds of weak intermolecular hydrogen bonding interactions between Fe(L2)32+cation and ClO4−anion, which lead to a close crystal packing. The intermolecular interactions have shown a significant influence on the physical properties, and magnetic measurements of complexes1and2in the solid state at the room temperature revealed that the weak intermolecular interactions in1resulted in HS (high-spin) state, while the strong interactions in2lead to LS (low-spin) state over the whole temperature range. [ABSTRACT FROM PUBLISHER]

A series of Fe(II) complexes with (ClO4)−(SeCN)−, (ClO4)−(SCN)−, (Fe2OCl6)2−, and 2(BF4)−counter-anions for complexes1–4, derived from dmbpy (4,4′-dimethyl-2,2′-bipyridine), were prepared. The single-crystal studies and the Hirshfeld surfaces analysis revealed that the (Fe2OCl6)2−anion results more distortional octahedral geometry of the cation than other anions. In particular, the (ClO4)−(SCN)−and (Fe2OCl6)2−anions lead to complexes2and3stabilized via C-H···π interactions and π···π interactions, which were not found in the other two complexes. However, the double-chain structure of complex4was formed by C-H···F and C-H···C hydrogen bonds interactions. Due to the influence of different anions, magnetic susceptibility measurements showed that complex1was in high-spin (HS) state and complex2was in low-spin (LS) state. [ABSTRACT FROM PUBLISHER]