Ligand Configuration-Induced\nManganese(II) Coordination Polymers: Syntheses, Crystal Structures,\nSorption, and Magnetic Properties

Abstract

Three new coordination\npolymers, {[Mn₃(pzbtz)₂(Cl)₂(H₂O)₂]·4H₂O}<i>_n</i> (<b>1</b>), {Mn₂(pzbtz)­(SO₄)­(H₂O)₃]·3H₂O}_<i>n</i> (<b>2</b>), and {[Mn₃(pzbtz)₃(H₂O)₃]·1.5DMA·2H₂O}_<i>n</i> (<b>3</b>), have been solvothermally synthesized\nwith MnCl₂/MnSO₄ and a bitriazole ligand, 5′-(pyrazin-2-yl)-2<i>H</i>,4′<i>H</i>-3,3′-bi­(1,2,4-triazole)\n(H₂pzbtz), in different solvent systems. H₂pzbtz\nshows different geometrical configurations and coordination modes,\nleading to the diverse three-dimensional (3D) frameworks of <b>1</b>–<b>3</b>. Complex <b>1</b> contains the\ntrinuclear Mn₃(tr)₄X₂ (X = Cl or\nH₂O) clusters and reveals an unobserved (3,4,8)-connected\nsqc929 topological framework with two types of cages. Complex <b>2</b> is a new (3,4,6)-connected network based on dinuclear Mn₂(tr)₂ clusters, and <b>3</b> shows an 8-connected\nbcu topology with a novel tetranuclear Mn₄(tr)₆ cluster. Complexes <b>1</b> and <b>2</b> show antiferromagnetic\nproperties, while <b>3</b> reveals spin-canting magnetic behavior\nwith an uncommonly high <i>T</i>_c around 44 K.\nIn addition, <b>1</b> also possesses good adsorption selectivity\nfor CO₂ over CH₄ and N₂ and an uncommon\ngate-opening phenomenon.