Two azido-bridged [2×2] cobalt() grids featuring single-molecule magnet behaviour

The self-assembly of Co( ii ) salts, pyridazine derivatives and azides afforded two azido-bridged [2×2] grid-type complexes {[(L) 4 Co II 4 (N 3 ) 4 ][BPh 4 ] 4 }·sol ( 1 , L = 3,6-bis(3,5-dimethyl-1 H -pyrazol-1-yl)pyridazine (pzdz) and sol = 4CH 3 CN·3CHCl 3 ·2CH 3 OH and 2 , L = 3,6-di(pyridin-2-yl)pyridazine (pydz) and sol = 4CH 3 CN). Upon comparison with other related grid-like complexes, the incorporation of end-on azido-bridges resulted in overall intramolecular ferromagnetic couplings, and thus endowed complexes 1 and 2 single molecule magnet behaviour with field-induced slow magnetic relaxation. Two Co( ii ) [2 × 2] grid-like clusters containing both pyridazine and azido bridges were reported to exhibit overall intramolecular ferromagnetic coupling and field-induced single-molecule magnet behavior with the effective energy barriers up to 56 K.