Technetium and rhenium complexes of mercapto-containing peptides 1. Tc(V) and Re(V) complexes with mercaptoacetyl diglycine (MAG2) and X-ray structure of AsPh4[TcO(MAG2)]·C2H5OH

The reaction of mercaptoacetyl diglycine (MAG₂) with technetium(V) gluconate in aqueous solution produced TcO(MAG₂)]⁻. A single X-ray structure determination was carried out for the tetraphenylarsonium salt. The dark brown crystals are monoclinic, space group P2(1)/n, with a=12.478(5), b=14.922(5), c=17.183(9) Å and Z=4. The TcO(MAG₂)]⁻ ion has a square pyramidal geometry with the technetium atom displaced by 0.756 Å towards the oxo ligand from the plane formed by the equatorial S,N,N,O atoms. The rhenium complex AsPh₄ReO(MAG₂)] was prepared analogously starting from Re(V) gluconate and characterized.