High dimensional coordination polymers based on transition metals, 1,2,4,5-benzenetetracarboxylate anion and 1,3-bis(4-pyridyl)propane nitrogen ligand

The reaction between 1,2,4,5-benzenetetracarboxylic acid (H4BT) and transition metal ions Mn+2, Co+2 and Cu+2 in the presence of the N-donor co-ligand 1,3-bis(4-pyridyl) propane (BPP) has afforded three new coordination polymers named, {[Mn4(BT)2(BPP)6(H2O)6]·4H2O}nMnBTBPP, {[Co2(BT)(BPP)2(H2O)6]·2H2O}nCoBTBPP and {[Cu2(BT)(BPP)2(H2O)]·6H2O}nCuBTBPP. They were characterized by a combination of analytical, spectroscopic and crystallographic methods. According to the thermal analysis results all the compounds present coordinated and lattice water molecules in the structures. In compounds MnBTBPP and CoBTBPP, the metal centers exhibit octahedral geometry while in compound CuBTBPP, the Cu+2 ions adopt square-planar and square-pyramidal geometries. In all cases, both BPP and BT ligands are coordinated to the metal sites in the bridging mode extending the polymeric networks. The BT ligand carboxylate groups act in a monodentate coordination mode as indicated by the Raman spectra data through the Δν [νasym(COO) − νsym(COO)] value.

Graphical abstractSynthesis, characterizations and crystal structures of three new coordination polymers involving the 1,2,4,5-benzenetetracarboxylic acid (H4BT); 1,3-bis(4-pyridyl)propane (BPP) ligand and the transition metals Mn+2, Co+2 and Cu+2 are reported. The compounds MnBTBPP and CuBTBPP are three-dimensional coordination polymers through M–L coordinative bonds while CoBTBPP is a 2D coordination polymer which is extended to a 3D supramolecular array by hydrogen bonds.Figure optionsDownload full-size imageDownload as PowerPoint slide