Two new ferrimagnetic MnII-carboxylate coordination polymers constructed from 5-tert-butyl isophthalic acid with (5/2, 15/2) and (5/2, 10/2) spin topologies

Abstract

Two new Mn^II coordination polymers, {[Mn₄(TBIP)₄(CH₃OH)₂]·(H₂O)₂}_n (1) and {[Mn₃(TBIP)₂(HTBIP)₂((CH₃)₂CHOH)₂]}_n (2) (H₂TBIP = 5-tert-butyl isophthalic acid), have been synthesized by a solvothermal reaction and characterized magnetically. Single-crystal X-ray diffraction studies reveal that 1 is a three-dimensional framework, which is based on a helical chain with a new periodic –J₁J₁J₂J₂– sequence. Compound 2 has a two dimensional layer structure constructed by trinuclear Mn(II) subunits that are extended into a 3D architecture by hydrogen bonds. Magnetic measurements indicate that both of the compounds show ferrimagnetic behaviour with different spin topologies. Compound 1 is a rare even-spin centre homometallic ferrimagnetic compound, in which the ferrimagnetism arises from the nature of carboxylate bridging modes. It is also the first example of a 3D homometallic ferrimagnetic compound, featuring a ferrimagnetic helical chain with a (5/2, 15/2) spin topology and a 1/2 magnetization plateau. Compound 2 is a three-spin centre homometallic ferrimagnetic complex with a (5/2, 10/2) spin topology and a 1/3 magnetization plateau.