A metamagnetic 2D copper(II)-azide complex with 1D ferromagnetism and a hysteretic spin-flop transitions

Compound [Cu-3(N-3)(6)(DMF)(2)](n) (1) was initially obtained in a serendipitous way during efforts to prepare a Cu-II/N-3(-) /Mebta coordination polymer (Mebta = 1-methylbenzotriazole). With the identity of 1 established by single-crystal crystallography, a rational preparative route to this complex was designed and carried out by reacting Cu(ClO4)center dot 6H(2)O with two equivalents of NaN3 in DMR Complex 1 is a 2D coordination polymer possessing mu(1,1,1) and mu(1,1,3) azido ligands. Its structure consists of {Cu-3(N-3)(6)(DMF2)} repeating units, which form chains that run parallel to the a axis; their bridging is achieved through end-on azides. The chains form sheets parallel to the ab plane through end-to-end azides. The magnetic properties of 1 have been studied in detail. The complex contains 1D ferromagnetic chains, based on a Cu-3(II) repeating unit, which can be viewed as having an S = 3/2 ground state. The ferromagnetic chains undergo antiferromagnetic coupling, which is weak enough to be overcome by moderate magnetic fields at 2 K leading to a metamagnetic spin-flop transition at 2.7 T The transition is first-order, leading to hysteresis of the order of 0.2 T.