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)

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)Å, ? = 98.98(5)°, and Z = 4. The structure has been refined to R = 0.048 for 2 693 observed reflections.