[Co5(µ3-OH)2(btec)2(bpp)]n: a three-dimensional homometallic molecular metamagnet built from the mixed hydroxide/carboxylate-bridged ferrimagnetic-like chains

Abstract

A three-dimensional homometallic complex [Co₅(µ₃-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 (btec⁴⁻) anion and 1,3-bis(4-pyridyl)-propane molecule (bpp). Within each chain, two µ₃-OH-bridged metal triangles connect to each other by sharing a common vertex to give rise to a bow-tie type Co₅(µ₃-OH)₂ subunit, which is joined to adjacent subunits by four µ_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.