Re(V) complexes containing the phenylimido (NPh2−) core and SNS-thiosemicarbazide ligands.

• Thiosemicarbazonate complexes containing the (ReNPh)3+ core have been successfully prepared. • Three complexes were studied by single-crystal X-ray diffraction. • A "3 + 2" mixed-ligand complex was obtained in order to completely envelope the metal center. • A prototype compound with potential for couplings to biomolecules was designed by means of DFT calculation. Reactions of thiosemicarbazone ligands (H 2 L1) with [ReX 3 (NPh)(PPh 3) 2 ] (X = Cl or Br) led to the formation of stable rhenium(V) complexes of composition [ReX(NPh)(HL1)(PPh 3)]X. The Re(V) complexes have been characterized by diverse techniques including FTIR, 1H and 31P NMR, elemental analysis, HRMS and single-crystal X-ray diffraction analysis. The crystal structures of the complexes rhenium complexes showed the formation a distorted octahedron environment around the Re(V) metal center, with the axial positions being occupied by the halogen atom and by the nitrogen atom from the phenylimido moiety, while the equatorial positions are occupied by the S,N,S -thiosemicarbazonate and the triphenylphosphane ligands. Furthermore, the "3 + 2" mixed ligand complex [Re(NPh)(L1b)(Et 2 btu)], where HEt 2 btu is N,N -diethyl- N '-benzoylthiourea, could be obtained from an equimolar reaction of [ReCl(NPh)(HL1)(PPh 3)]Cl with the bidentate thiourea in the presence of NEt 3. Finally, DFT calculations were applied in order to propose a complex suitable for biocouplings upon substitution of a NH 2 group at the 4-position of the phenylimido ligand in [Re(NPh)(L1b)(Et 2 btu)]. The compounds studied here represent the first examples of phenilimidorhenium(V) complexes with thiosemicarbazones. [ABSTRACT FROM AUTHOR]