A Unique Cobalt(II)-Based Molecular Magnet Constructed of Hydroxyl/Carboxylate Bridges with a 3D Pillared-Layer Motif

A new pillared-layer coordination polymer, [Co3(pybz)2(pico)2]n (1; pybz = 4-(pyridin-4-yl)benzoate, pico = 3-hydroxypicolinate), contains rare 2D [Co3(pico)2]n2n+ layers formed by linear cobalt(II) trimers through the unusual μ4-κN,O:κO′-μ2:κO′′-μ2 bridging mode of pico ligands, which are further cross-pillared by exotridentate bridging pybz ligands to form a three-dimensional structure with an unusual uninodal 8-connected body-centered-cubic topology. The bulk magnetic behavior of 1 exhibits ferrimagnetic long-range ordering below 2.6 K, which mainly arises from the cooperative magnetic effect of the intra- and intertrimer arrangements in the 2D magnetic system based on the nature of the exchange modes of μ2-hydroxyl, μ2-carboxylate oxygen, and 1,1,3-μ3-carboxylate bridges.