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Abstract
Mononuclear and binuclear oxorhenium(V) complexes were prepared from the reaction of 8,17‐dimethyl‐5,7,14,16‐tetrahydrodibenzo[a,h]annulene‐6,15‐dione (H2N4L) with the oxorhenium(V) complex H2[ReOCl5] in 6 M HCl solution. The composition of the prepared complexes depends on the concentration of hydrochloric acid in which the starting rhenium(V) complex is dissolved. The mononuclear oxorhenium(V) complex, [ReO(H2N4L)(H2O)]Cl3, was obtained in 6 M HCl solution, while the binuclear complex, [Re2O3(H2N4L)2]Cl4·2H2O, was obtained in 2 M HCl solution. The reaction of H2N4L mixed with PPh3, NaSCN or 2‐aminopyridine, with the starting oxorhenium(V) complex in 6 M HCl solution, yielded the mononuclear complexes, [ReO(H2N4L)(PPh3)]Cl3·H2O, [ReO(H2N4L)(SCN)]Cl2·½ H2O and [ReO(H2N4L)(C5H6N2)]Cl3, respectively. The reaction of NH3 gas with the isolated solid complex, [ReO(H2N4L)(H2O)]Cl3, yielded a binuclear oxorhenium(V) complex, [Re2O3(H2N4L)2]Cl4. These complexes decompose through several isolable, as well as non‐isolable, intermediates during heating. [Re2O3(N4L)]Cl4, [ReO(N4L)Cl], [ReO(N4L)(PPh3)]Cl, [ReO(N4L)(SCN)] and [ReO(N4L)(C5H6N2)]Cl, were synthesized pyrolytically in the solid state from the corresponding rhenium complexes. The electronic absorption spectra and magnetic moments indicate an octahedral configuration for the complexes. The macrocyclic ligand in these complexes behaves either as neutral tetradentate or dianionic tetradentate towards the oxorhenium ions. The structures of all complexes and the corresponding thermal products were elucidated by elemental analyses, conductance, IR and electronic absorption spectra, magnetic moments, 1H NMR and TG‐DSC measurements as well as by mass spectroscopy.
Acknowledgment
The author expresses his great thanks to Dr. Usama Fahmy Ali, Department of Biological and Geological Sciences, Faculty of Education, Ain Shams University, Cairo, Egypt, for evaluating the biological assays.
