Synthesis, crystal, and molecular structure of coordination polymers constructed by self-assembly of NiN4 cores with 2,2′-iminodibenzoate and nitroprusside ions

Two coordination compounds of compositions [Ni(L-1)(idba)(H2O)]center dot 1.5 H2O (1) and [Ni(L-2)Fe(CN)(5)NO]. C2H5OH (2) where L-1 is N, N-bis(3-aminopropyl)ethylenediamine, L-2 is 2,12-dimethyl-3,7,11,17-tetraazabicyclo [11.3.1]heptadeca-1(17),2,11,13,15-pentaene, and idba(2)- is 2,2'-iminodibenzoate have been synthesized and characterized by elemental analysis, IR spectroscopy, thermal analysis, and single-crystal X-ray diffraction. Complex I crystallizes in the monoclinic space group P2(1)/n (No. 14) with a = 9.810(2) angstrom, b = 10.230(2) angstrom, c = 25.350(5) angstrom, V = 2543.6(9) angstrom(3), Z = 4, and R = 0.0727. The nickel atom is six-coordinated by four N atoms of amine and two 0 atoms of water and idba2-. The molecular packing of the complex comprises of an infinite one-dimensional layered network in which the molecules in the crystal are held together by a system of hydrogen bonding. Complex 2, however, crystallizes in the space group C2/c (No. 15) of the monoclinic system with a = 19.7990(4) angstrom, b = 14.9440(3) angstrom, c = 19.8800(3) angstrom, V = 5115.90(17) angstrom(3), Z = 4, and R = 0.0540. The Ni ion in compound 2 has a slightly distorted octahedral arrangement of the N-4 donor atoms of primary ligand L-2 and two N-donor atoms of the secondary nitroprusside ligand. The structure of 2 displays an extended one-dimensional network formed by linear [-Ni-NC-Fe-CN-] units. A cyclic voltammetric study shows that compound 1 undergoes a quasireversible oxidation attributable to Ni2+ -> Ni3+ in the range 300-420 mV vs SCE.