Nickel(II) and manganese(II) 1D chain coordination polymers with 1,2,4,5-benzenetetracarboxylato anions

Five new coordination complexes were synthesized under ambient conditions in water, or water/ethanol by combining a Mn2+ or Ni2+ salt with BTEC and an imidazole derivative forming [Mn(Him)4(H2O)2][Mn(BTEC)(Him)2(H2O)2]·4H2O (1), [Ni(Him)4(H2O)2][Ni(BTEC)(Him)2(H2O)2]·4H2O (2), [2-MeH2im]2[Mn(BTEC)(H2O)4]·5H2O (3), [Mn(4-MeHim)6][Mn(BTEC)(H2O)4]·H2O (4), and [Mn2(BTEC)(HBzim)4(H2O)6]·2H2O (5) (BTEC=1,2,4,5-benzenetetracarboxylate; Him=imidazole; 2-MeH2im=2-methylimidazolium; 4-MeHim=4-methylimidazole; HBzim=benzimidazole). Complexes 1–5 were characterized by TGA, FT-IR, elemental analysis and X-ray crystallography. Complexes 1–5 all crystallize in the triclinic space group P1̄. Complexes 1–4 are coordination polymers, possessing 1D linear chain structures, while complex 5 is a discrete bimetallic complex. The anionic linear 1D chains in 1–4 are comprised of BTEC ligands that bridge between metal atoms. The cations are either metal complexes (1, 2 and 4) or protonated 2-MeHim (3), which has a lower pKb.