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

Four tetrazolate (tz(-))-based magnetic metal-organic frameworks, [Cu-5(mu(3)-OH)(2)(SO4)(2)(tz)(4)](n) (1), {[Cu-3(tz)(4)Cl-2]center dot 1.4CH(3)OH}(n) (2), [Cu(N-3)(tz)](n) (3) and {[Cu-5(tz)(9)]Cl center dot 4H(2)O}(n) (4), 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 {Cu-5(mu(3)-OH)(2)}(8+) cores in 1 are periodically extended by mixed mu(3)-/mu(4)-tz(-) and mu(4)-SO42- heterolinkers, while the linear {Cu-3(mu-Cl)(2)}(4+) blocks in 2 are repeatedly intersected by ditopic mu(3)-tz(-) connectors. In contrast, the square grid-shaped network of 3 is constructed from linear {Cu(mu(1,1)-N-3)}(+) chains and mu(3)-tz(-) linkers. Complex 4 consists of trigonal-prismatic {Cu-8(mu(3)-tz)(6)}(10+) subunits, which are interlinked into hexagonal microporous architecture by mirror-symmetry mu(4)-tz(-) ligands. Thus, the various subunits of 1-4 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-5(II) and Cu-3(II) subunits eventually lead to unusual ferrimagnetic and canted antiferromagnetic properties in 1 and 2. Strong antiferromagnetic couplings mediated by the mixed tz(-) and/or azido bridges result in overall S = 0 spin ground-states of 3 and 4.