Synthesis and characterization of technetium(V) and rhenium(V) oxo-complexes with Schiff-base ligands containing the ONN donor-atom set. Molecular structure of trans-dichloro-oxo[1-(8′-quinolyliminomethyl)-2-naphtholato-NN′O]technetium(V)

Abstract

Six-co-ordinate complexes of technetium(V) and rhenium(V) containing the MO3+(M = Tc or Re) core were synthesized from [MOCl4]–via ligand-exchange reactions using tridentate Schiff-base ligands containing the ONN donor-atom set. The complexes of general formula [MOCl2Ln][n= 1 – 4; L1= 1-(8′-quinolyliminomethyl)-2-naphtholate, L2=N-(8′-quinolyl)salicylideneiminate, L3= 3-methoxy-N-(8′-quinolyl)salicylideneiminate, L4=N-(2′-dimethylaminoethyl)salicylideneiminate] were characterized by means of physico-chemical measurements and [TcOCl2L1] also by X-ray diffraction analysis. The technetium co-ordination environment in the last complex is a distorted octahedron with the N2O ligand-atom set and the oxo-oxygen occupying the equatorial plane and the two chlorine atoms, respectively trans, in axial positions. The complex crystallizes in monoclinic space group P21/a with a= 23.262(8), b= 7.301(4), c= 11.444(5)A, β= 98.98(5)°, and Z= 4. The structure has been refined to R= 0.048 for 2 693 observed reflections.