Abstract
Azulene-embedded heterometallacycles can be handled in air and are expected to have a glossy color derived from the azulenyl ligand. However, very few studies have clearly described the synthesis, structure, and effects of metal species. In this study, the reactions of diethyl 2-hydroxyazulene-1,3-dicarboxylate (DEHA, other abbreviation as H-L) with various metals were investigated to synthesize metal complexes (Metals-L). Metals-L were synthesized by the reaction of metal acetates (Pd, Cu, Ni, Co, and Zn acetate) with DEHA and Cs(2)CO(3). Single-crystal X-ray structural analysis showed that Pd-L and Cu-L had mononuclear planar and binuclear structures, respectively. In the case of zinc acetate, the formation of a one-dimensional coordination polymer, [ZnCs-(OC(10)H(5)(COOC(2)H(5))(2))(3)] (n) , was confirmed. For cobalt and nickel acetates, the formation of similar coordination polymers was suggested by mass spectrometry, infrared spectrometry, and energy-dispersive X-ray spectrometry. These complexes were mixed in poly-(methyl methacrylate) (PMMA), and the PMMA composite films exhibited coloration corresponding to the color of the complexes. When DEHA was mixed with titanium tetraisopropoxide and Cs(2)CO(3) in an alcohol (iPrOH, nBuOH, or allyl alcohol), transesterification was observed by nuclear magnetic resonance spectroscopy. This transesterification was necessary for both titanium tetraisopropoxide and Cs(2)CO(3), and a facile transesterification reaction of DEHA was observed for the first time.