A 3D metal–organic framework, [Na{Mn3(Hbtc)2(btc)}·5H2O]n (1) (H3btc = 1,3,5-benzene tricarboxylic acid), was synthesized under hydrothermal conditions. The structure of 1 was established by single crystal X-ray diffraction analysis; 1 crystallizes in the monoclinic space group P2/c, a = 9.753(3) Å, b = 12.751(2) Å, c = 14.174(4) Å, β = 109.41(1)°. The complex 1 is isostructural to previously reported MIL-45 and consists of one dimensional wave like chains of carboxylate bridged hexa-coordinated Mn(II) ions. Variable temperature magnetic susceptibility measurements revealed dominant antiferromagnetic exchange interactions and the intra-chain exchange constants J1 = -2.4 cm−1 and J2 = -0.6 cm−1 compare well with literature values for similar materials. Inter-chain interactions are expected to be very small in this compound and there is no indication of magnetic ordering phenomena in the temperature range from 300–2 K.
