[Co₅(₃-OH)₂(btec)₂(bpp)] _n: A three-dimensional homometallic molecular metamagnet built from the mixed hydroxide/carboxylate-bridged ferrimagnetic-like chains

A three-dimensional homometallic complex [Co₅( ₃-OH)₂(btec)₂(bpp)]_n is built from the mixed hydroxide/carboxylate bridged cobalt(ii) chains linked by the 1,2,4,5-benzenetetracarboxylate (btec^4-) anion and 1,3-bis(4-pyridyl)-propane molecule (bpp). Within each chain, two ₃-OH-bridged metal triangles connect to each other by sharing a common vertex to give rise to a bow-tie type Co₅(₃-OH) ₂ subunit, which is joined to adjacent subunits by four _1,1-carboxylate bridges to form a step-like metal-oxygen backbone. The magnetic studies revealed that the coexistence of ferromagnetic and antiferrimagnetic interactions resulted in a ferrimagnetic-like behavior of the homometallic chains. Below a critical temperature (T_N = 12.5 K), bulk antiferromagnetic ordering was observed at low field due to the weak interchain antiferromagnetic interactions. A metamagnetic transition occurred at a magnetic field of ca. 5 kOe at 2 K.