Chemical Design Of The Heterodifunctionalized Iron(Ii) Clathrochelates With Terminal Biorelevant Carboxyl Group And Reactive Triple C C Bond: Synthesis, Structure, Redox Properties And Their Stability In Various Media

The heterodifunctionalized iron(II) clathrochelates, the molecules of which contain the terminal biorelevant carboxyl and reactive triple C C groups were obtained using the two-step synthetic procedures by a subsequent substitution of their dichloroclathrochelate precursor with para-carboxyphenylthiolate anion and 2-propargylamine. The complexes obtained were characterized using elemental analysis, HR-APPI and MALDI-TOF mass spectrometries, UV-Vis, H-1, C-13{H-1}, B-11 and F-19 NMR spectroscopies, and by the single crystal X-ray diffraction for an iron(II) monochloroclathrochelate with terminal propargylamine group. Its FeN6-coordination polyhedron possesses a distorted trigonal prismatic - trigonal-antiprismatic geometry with the average distortion angle phi of approximately 26.1 degrees. Fe-N distances in this monoribbed-functionalized molecule vary in a narrow range from 1.883(3) to 1.901(4) angstrom and the height h of the above polyhedron is equal to 2.30 angstrom. Cyclic voltammograms study of these complexes contain the single cathodic wave assigned to the metal-centered processes of the cathodic Fe2+/+ reduction and anodic Fe+/2+ re-oxidation, thus suggesting their quasi-reversible character. Chemical reactions (including a complete decomposition and a reductive hydrodehalogenation of the macrobicyclic molecules) of the propargylamine and propargylamide iron(II) clathrochelates was studied in various media and under the different experimental conditions using TLC, high-resolution APPI mass, NMR and UV-vis spectra, suggesting a complete slow destruction of the macrobicyclic frameworks of their molecules in aqueous solutions (including those modeling the physiological conditions).