Influence of Terminal Acryloyl Arms on the Coordination Chemistry of a Ditopic Pyrimidine鈥揌ydrazone Ligand: Comparison of Pb(II), Zn(II), Cu(II), and Ag(I) Complexes
文摘
A new ditopic pyrimidine鈥揾ydrazone ligand, 6-hydroxymethylacryloyl-2-pyridinecarboxaldehyde, 2,2鈥?[2,2鈥?(2-methyl-4,6-pyrimidinediyl)bis(1-methylhydrazone)] (L2), was synthesized with terminal acryloyl functional groups to allow incorporation into copolymer gel actuators. NMR spectroscopy was used to show that L2 adopted a horseshoe shape with transoid鈥搕ransoid pym鈥揾yz鈥損y linkages. Metal complexation studies were performed with L2 and salts of Pb(II), Zn(II), Cu(II), and Ag(I) ions in CH3CN in a variety of metal to ligand ratios. Reacting L2 with an excess amount of any of the metal ions resulted in linear complexes where the pym鈥揾yz鈥損y linkages were rotated to a cisoid鈥揷isoid conformation. NMR spectroscopy showed that the acryloyl arms of L2 did not interact with the bound metal ions in solution. Seven of the linear complexes (1鈥?b>7) were crystallized and analyzed by X-ray diffraction. Most of these complexes (4鈥?b>7) also showed no coordination between the acryloyl arms and the metal ions; however, complexes 1鈥?b>3 showed some interactions. Both of the acryloyl arms were coordinated to Pb(II) ions in [Pb2L2(SO3CF3)4] (1), one through the carbonyl oxygen donor and the other through the alkoxy oxygen donor. One of the acryloyl arms of [Cu2L2(CH3CN)3](SO3CF3)4 (2) was coordinated to one of the Cu(II) ions through the carbonyl oxygen donor. There appeared to be a weak association between the alkoxy donors of the acryloyl arms and the Pb(II) ions of [Pb2L2(ClO4)4]路CH3CN (3). Reaction of excess AgSO3CF3 with L2 was repeated in CD3NO2, resulting in crystals of {[Ag7(L2)2(SO3CF3)6(H2O)2] SO3CF3}鈭?/sub> (8), the polymeric structure of which resulted from coordination between the carbonyl donors of the acryloyl arms and the Ag(I) ions. In all cases the coordination and steric effects of the acryloyl arms did not inhibit isomerization of the pym鈥揾yz bonds of L2 or the core shape of the linear complexes.