Coligand-directed synthesis of five Co(II)/Ni(II) coordination polymers with a neutral tetradentate ligand: syntheses, crystal structures, and properties

The solvothermal reactions of 1,1'-oxybis[3,5-di-4-pyridine]-benzene (L) and transition metal cations (Co and Ni) afford five novel coordination polymers in the presence of flexible bridging ligands (4,4'-H(2)nba = 4,4'-dicarboxydiphenylamine, H(2)cam = D-camphoric acid, 4,4'-H(2)sdb = 4,4'-sulfonyldibenzoic acid, H(2)chdc = 1,4-trans-cyclohexanedicarboxylic acid), namely {[Co2L2(OH)(2)(nba)]center dot 2DMF}(n) (1), {[CoL(cam)-(H2O)]}(n) (2), {[Co-3(L)(4,4'-sdb)(3)(H2O)]center dot 1.5CH(3)CN center dot 4H(2)O}(n) (3), {[Ni-3(L)(4,4'-sdb)(3)(H2O)]center dot 1.5CH(3)CN center dot 4H(2)O}(n) (4), and {[Ni2L2(chdc)(2)(H2O)(2)]center dot(H2O)(3)}(n) (5) (DMF = N,N-dimethylformamide). Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectroscopy, and powder X-ray diffraction. Complex 1 reveals a 2-fold interpenetrating three-dimensional (3D) framework with the Schlafli symbol {4.8.10(4)}{4.8.10} topology. Compound 2 crystallizes in the achiral space group with the D-camphorate ligand racemized. Compounds 3 and 4 reveal similar structure with the {3.4(4).6}{3(2).4(8).5(9).6(9)} topology based on a linear trinuclear building block M-3(OOCR)(6) (M = Co(II) or Ni(II))). Compound 5 is a wavy sheet, where both carboxylate and L ligands act as bidentate ligands. Moreover, UV-Visible absorption spectra of complexes 1-3, 5 and the magnetic properties of 3 have been investigated.