Three-Dimensional Porous Metal−Organic Frameworks Exhibiting Metamagnetic Behaviors: Synthesis, Structure, Adsorption, and Magnetic Properties

Two isomorphous 3D porous metamagnets, {[M₆(N₃)₁₂<b>L</b>₆]·(H₂O)₁₃}_∞ (M = Ni^II, <b>1</b>; Co^II, <b>2</b>), have been constructed from 2-(1,3,4-thiadiazol-2-ylthio)acetic acid (H<b>L</b>), with azido as the auxiliary ligand. Single-crystal X-ray analysis indicates that the complexes possess hexagonal channels with dimensions of about 8.3 Å × 8.3 Å along the <i>c</i> axis and void space of about 25% per cell volume. Hydrogen adsorption measurements at 740 Torr and 77 K reveal that hydrogen uptakes of 0.68 and 0.83 wt % were observed in <b>1</b> and <b>2</b>, respectively, with BET surface areas of 309 and 328 m²/g. Magnetic measurement reveals that both of them exhibit global metamagnetic behaviors resulted from strong intrachain ferromagnetic couplings and weak interchain antiferromagnetic interactions, with critical fields of 22 kOe and 6 kOe for <b>1</b> and <b>2</b>, respectively.