Organometallic chalcone complexes functionalized with a macrocyclic fragment [( 5 -C 5 H 4 C(O)CH=CH-4-benzo-15-crown-5)MLn] (ferrocenyl, cyrhetrenyl, and cymantrenyl) have been synthesized. The complexes are characterized by IR spectroscopy, 1 H and 13 C NMR spectroscopies, elemental analyses, and HR-MS. The stereochemistry for the chalcone compounds was determined using the 1 H and 13 C NMR spectroscopy data, which indicated that they are isolated as a single isomer (E). In addition, the syntheses of the chalcone-imine derivatives are described, and they adopt an anti-(E,E) conformation in solution, confirmed by the X-ray crystal structures in the solid state. The UV-Visible and electrochemical behavior of the organometallic complexes are reported. Keywords: Organometallic chalcone and imine complexes, crown ether, crystal structures. examples of their application as chemosensors. Delavaux-Nicot et al. have investigated a series of ferrocenyl chalcones, mono and 1,1'-disubstituted, functionalized with an amine moiety or an aza-macrocycle. 13 These metallo-ligands have shown selectivity toward Ca 2+ and Ba 2+ in acetonitrile. Another important class of functionalized rhenium(I) complexes with aza-crown ether pendants, synthetized by Yam et al., exhibit a high specificity towardPb(II). 14 Previously, our research group reported the synthesis of new cyrhetrenyl tricarbonyl complexes functionalized with 4'-benzo-crown or 2-methyl-crown ether fragments, bridged by an imine linker. The cyclic voltammograms showed positive anodic waves arising from the Re(II)/Re(I) redox process (I). It was concluded that the size of the crown ether did not change the anodic potential significantly. Nevertheless, the metal centered redox processes of complexes that possess a methylene moiety were shifted to positive potentials compared to a benzo group. 15 In this work, we report the synthesis, X-ray structures and electrochemical and spectroscopic behaviour of new ferrocenyl, cyrhetrenyl and cymantrenyl complexes functionalized with 4'-benzo-15-crown-5 fragment. In addition we have included the synthesis of related species with a chalcone-imine as linker.2. Results and discussion.
Synthesis of the organometallic chalcones 2-3.The compounds were synthesized following a procedure similar to that described for ferrocenyl and cymantrenyl chalcone derivatives. 11,16 It is based on the Claisen-Schmidt reaction involving the condensation of the organometallic ketones 1a-c and the corresponding crown ether or organic aldehydes Id-e (Scheme 1). Derivatives 2a-c and 3awere obtained by reaction of the corresponding precursors in the presence of NaOH and were dissolved in water/ethanol mixed solvent for greater solubility of the components. A modification of the experimental procedure was used for the preparation of the cyrhetrenyl derivative 3b. The carbanion containing solution was added dropwise to an ethanolic solution of terephthalaldehyde (Ie) over a period of 2 h. in order to control the proportion of nucleophile generated. The genera...