Color Tuning of a Nickel Complex with a Novel N2S2 Pyridine-Containing Macrocyclic Ligand

A. TAMAYO; J. CASABÓ; L. ESCRICHE; C. LODEIRO; B. COVELO; C. D. BRONDINO; R. KIVEKÄS; R. SILLAMPÄÄ

INORGANIC CHEMISTRY

American Chemical Society

Año: 2006 vol. 45 p. 1140 - 1149

0020-1669

The novel pyridine-containing 14-membered macrocycle 3,11-dithia-7,17-diazabicyclo[11.3.1]heptadeca-1(17),13,-15-triene (L), which contains an N2S2 donor set, was synthesized, and its protonation behavior was studied by absorption titration with CH3SO3H. The reaction of L with Pd(II) was studied spectroscopically, and the squareplanar complex [Pd(L)](BF4) was isolated and characterized. The reactions between L and NiX2â6H2O (X ) BF4, ClO4) in ethanol or acetonitrile afforded the octahedral complexes [Ni(CH3CN)(H2O)(L)](X)2 and [Ni(H2O)2(L)](X)2,respectively. The square-planar complexes [Ni(L)](X)2 were obtained by heating these octahedral complexes. Spectrophotometric titrations of [Ni(L)](BF4)2 were performed with neutral and negatively charged ligands. The color of nitromethane solutions of this square-planar complex turns from red to cyan, purple, blue, yellow-green, and pink following addition of halides, acetonitrile, water, pyridine, and 2,2¢-bipyridine, respectively. X-ray structuralanalyses were carried out on the {[Ni(ClO4)(H2O)(L)][Ni(H2O)2(L)]}(ClO4)3, [Ni(CH3CN)(H2O)(L)](ClO4)2, [{Ni(L)}2-(í-Cl)2](ClO4)2, and [{Ni(L)}2(í-Br)2]Br2â2CH3NO2 complexes.