Ligand Configuration-Induced Manganese(II) Coordination Polymers: Syntheses, Crystal Structures, Sorption, and Magnetic Properties.

ABSTRACT

Three new coordination polymers, {[Mn3(pzbtz)2(Cl)2(H2O)2]·4H2O}n (1), {Mn2(pzbtz)(SO4)(H2O)3]·3H2O}n (2), and {[Mn3(pzbtz)3(H2O)3]·1.5DMA·2H2O}n (3), have been solvothermally synthesized with MnCl2/MnSO4 and a bitriazole ligand, 5'-(pyrazin-2-yl)-2H,4'H-3,3'-bi(1,2,4-triazole) (H2pzbtz), in different solvent systems. H2pzbtz shows different geometrical configurations and coordination modes, leading to the diverse three-dimensional (3D) frameworks of 1-3. Complex 1 contains the trinuclear Mn3(tr)4X2 (X = Cl or H2O) clusters and reveals an unobserved (3,4,8)-connected sqc929 topological framework with two types of cages. Complex 2 is a new (3,4,6)-connected network based on dinuclear Mn2(tr)2 clusters, and 3 shows an 8-connected bcu topology with a novel tetranuclear Mn4(tr)6 cluster. Complexes 1 and 2 show antiferromagnetic properties, while 3 reveals spin-canting magnetic behavior with an uncommonly high Tc around 44 K. In addition, 1 also possesses good adsorption selectivity for CO2 over CH4 and N2 and an uncommon gate-opening phenomenon.