Two polymeric nickel(II) complexes with aromatic benzene-1,2,4,5-tetracarboxylate and pyridine-2,5-dicarboxylate linkers

Abstract

mu-Benzene-1,2,4,5-tetracarboxylato-kappa O-2(1):O-4) bis[aquabis(2,2-methylpropane-1,3-diamine-kappa N-2,N') nickel(II)] methanol disolvate tetrahydrate, [Ni-2(C10H2O8)(C5H14N2)(4)(H2O)(2)]center dot 2CH(4)O center dot 4H(2)O, (I), is dinuclear, with elemental units built up around an inversion centre halving the benzene-1,2,4,5-tetracarboxylate (btc) anion, which bridges two symmetry-related Ni-II cations. The octahedral Ni polyhedron is completed by two chelating 2,2-methylpropane-1,3-diamine (dmpda) groups and a terminal aqua ligand. Two methanol and four water solvent molecules are involved in a number of N-H center dot center dot center dot O and O-H center dot center dot center dot O hydrogen bonds which define a strongly bound two-dimensional supramolecular structure. The structure of catena-poly[[[bis(2,2-methylpropane-1,3-diamine-kappa N-2,N') nickel(II)]-mu-pyridine-2,5-dicarboxylato-kappa O-3(5): N,O-2[(2,2-methylpropane-1,3-diamine-kappa N-2,N') nickel(II)]-mu-pyridine-2,5-dicarboxylato-kappa N-3,O-2:O-5] octahydrate], {[Ni-2(C7H3NO4) 2(C5H14N2)(3)]center dot 8H(2)O}(n), (II), is polymeric, forming twisted chains around three independent Ni centres, two of which lie on inversion centres and the third in a general position. There are three chelating dmpda ligands (one disordered over two equally populated positions), which are each attached to a different cation, and two pyridine-2,5-dicarboxylate (pdc) anions, both chelating the Ni centre in general positions through an-O-C-C-N-loop, while acting as bridges to the remaining two centrosymmetric Ni atoms. There are, in addition, eight noncoordinated water molecules in the structure, some of which are disordered.