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

Two new Mn-II coordination polymers, {[Mn-4(TBIP)(4)(CH3OH)(2)]center dot(H2O)(2)}(n) (1) and {[Mn-3(TBIP)(2)(HTBIP)(2)((CH3)(2)CHOH)(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 -J(1)J(1)J(2)J(2)-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.