Three dimensional metal–malonate frameworks with pillared layered architecture: Unusual role of metal–chelate as pillar

One hetero-bimetallic Cu(II)/Cd(II) compound, [CdII(H2O)2][CuII(mal)2(H2O)2]n (1) (H2mal = malonic acid) has been synthesized and characterized using single crystal X-ray crystallography, thermogravimetric (TG) studies and X-ray powder diffraction (XRPD) measurements. The compound crystallizes in orthorhombic Pbcn space group having cell dimensions a = 6.6260(12) Å, b = 13.958(2) Å and c = 13.052(2) Å. The solid state structure of compound 1 demonstrates a 3D pillared layered coordination network generated through the simultaneous bridging as well as chelating mode of malonate towards the Cd(II) and Cu(II), respectively. TG analysis reveals relatively high thermal stability for the compound (decomposition temperature ∼320 °C). The thermal study also reveals that the coordinated waters attached to both the metal centers (Cd(II) and Cu(II)) are reversibly lost and gained and this behavior is also corroborated by XRPD studies.