Novel sandwich coordination polymers composed of cobalt(II), 1,2,4,5-benzenetetracarboxylato ligands, and homopiperazonium cations

Two novel cobalt(II) coordination polymers, (H(4)hpz)[Co-3(BTEC)(2)(H2O)(12)].11H(2)O (1) and (H(4)hpz)[Co(BTEC)(H2O)(3)].3H(2)O (2) (H(4)hpz = homopiperazonium; BTEC = 1,2,4,5-benzenetetracarboxylate), have been synthesized under aqueous conditions at room temperature and structurally characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the triclinic space group P (1) over bar with a = 9.823(4) Angstrom, b = 11.587(4) Angstrom, c = 20.385(7) Angstrom, alpha = 95.10(2)degrees, beta = 92.423(19)degrees, gamma = 98.90(2)degrees, and Z = 2. Compound 2 also crystallizes in the triclinic space group P (1) over bar with a = 9.7755(17) Angstrom, b = 11.208(3) Angstrom, c = 11.224(2) Angstrom, alpha = 60.304(12)degrees, beta = 73.687(12)degrees, gamma = 84.311(14)degrees, and Z = 2. Both compounds have layered structures. In the case of 1, homopiperazonium cations and 1D anionic chains of [Co(BTEC)(H2O)(4)](n)(2-) are sandwiched between 2D sheets Of [Co-2(BTEC)(H2O)(8)](n). In the case of 2, homopiperazonium cations alone are sandwiched between 2D sheets of [Co(BTEC)(H2O)(3)](n)(2-).