A 3D Cu(II) tetrazolate coordination polymer based on pentanuclear units with a large coercive field

A novel 3D coordination polymer {[Cu-4.5 (BTZE)(1.5) (mu(3)-OH)(3)(mu-OH)(SO4)(H2O)(1.5)center dot 4H(2)O]}(n) (1) was synthesized by a solvothermal reaction of 1,2-bis(tetrazol-5-yl) ethane (BTZE) with copper sulfate. Compound (1) contained triangular [Cu-3(mu(3)-OH)] cluster based magnetic Delta-chains linked with in situ generated mu(2)-BTZE ligands to form a 2D cyclic annular layer. This 2D layer structure was further modified with sulfate and symmetry-related mu(3)-OH groups, extending to a 3D coordination framework structure. The magnetic performance of (1) was characterized in the temperature range of 2-300 K in terms of direct-current and alternating-current magnetic susceptibilities, revealing that (1) was a canted ferromagnet with a critical temperature (T-c) of 9.5 K. Notably, (1) behaved as a hard magnet with a coercive field of 2.3 kOe at 2 K, showing significant unique characteristics compared to those of the reported spin canting systems based on pure Cu(II) ions.