Four tetrazolate-based 3D frameworks with diverse subunits directed by inorganic anions and azido coligand: hydro/solvothermal syntheses, crystal structures, and magnetic properties.

Abstract

Four tetrazolate (tz(-))-based magnetic metal-organic frameworks, [Cu5(μ3-OH)2(SO4)2(tz)4]n (), {[Cu3(tz)4Cl2]·1.4CH3OH}n (), [Cu(N3)(tz)]n () and {[Cu5(tz)9]Cl·4H2O}n (), were hydro/solvothermally synthesized, and structurally and magnetically characterized. Structural analyses reveal that the former two samples exhibit the same eight-connected topological framework assembled from different subunits. Hourglass-shaped {Cu5(μ3-OH)2}(8+) cores in are periodically extended by mixed μ3-/μ4-tz(-) and μ4-SO4(2-) heterolinkers, while the linear {Cu3(μ-Cl)2}(4+) blocks in are repeatedly intersected by ditopic μ3-tz(-) connectors. In contrast, the square grid-shaped network of is constructed from linear {Cu(μ1,1-N3)}(+) chains and μ3-tz(-) linkers. Complex consists of trigonal-prismatic {Cu8(μ3-tz)6}(10+) subunits, which are interlinked into hexagonal microporous architecture by mirror-symmetry μ4-tz(-) ligands. Thus, the various subunits of are significantly tuned by the co-coordination of the inorganic anions and/or the azido co-ligand, and the backbone extensions are directed by the polytopic tetrazolate ligand. Magnetically, different ordering arrangements of the non-zero magnetizations produced in the local Cu(II)5 and Cu(II)3 subunits eventually lead to unusual ferrimagnetic and canted antiferromagnetic properties in and . Strong antiferromagnetic couplings mediated by the mixed tz(-) and/or azido bridges result in overall S = 0 spin ground-states of and .