Tc(V) complexes with Schiff base derivatives of glucosamine

A number of Schiff base complexes of Tc(V) and (III) have recently been reported indicating the pronounced stabilizing effect of this group toward different technetium centers. The structure of the Tc(V)-derivatives was always found to be dominated by the electronic requirements of the Tc=O oxo-moiety: in particular it has been observed that bidentate, monoanionic Schiff bases give rise to monosubstituted or bisubstituted, distorted octahedral complexes in which one base is arranged in order to place the charged atom (oxygen) in transposition to the Tc=O multiple bond. This result was also observed in rhenium(V)-oxo-compounds with bidentate Schiff bases and with salicylaldehyde and it is believed to hold for all monoanionic, bidentate ligands including N.O or O.O pairs as donor atoms. The authors report here the first example of an oxo-complex of Tc(V) in which this rule is not followed, obtained by reacting the oxotetrachlorotechnetium(V) anion with an excess of glucose-derived Schiff base