Synthesis of new mixed-ligands Tc complexes containing monodentate phosphine and isothiocyanato ligands: Crystal structures of complexes Tc(P(C3H7)3)2(NCS)4, Tc(P(CH3)2Ph)4(NCS)2 and Tc(P(OCH3)Ph2)4(NCS)2·1/2CH2Cl2

Three mixed-ligand neutral technetium complexes containing monodentate phosphine and isothiocyanato ligands have been synthesized and studied by crystallographic methods. In the Tc(IV) compound trans-Tc(P(C3H7)3)2(NCS)4, the Tc atom is located on an inversion centre. The TcP bond distances are 2.519(3) Å while the TcN bonds are 1.991(6) and 2.003(6) Å. Two Tc(II) compounds containing tetrasubstituted phosphine ligands were also characterized by X-ray diffraction methods. In trans-Tc(P(CH3)2Ph)4(NCS)2 (II), the Tc atom is located on a twofold axis. The TcP bond distances are 2.429(2) and 2.482(2) Å while the TcN bonds are 2.052(6) Å. In trans-Tc(P(OCH3)Ph2)4(NCS)2·1/2CH2Cl2, the TcP bond distances vary between 2.423(1) and 2.442(1) Å, while the TcN bonds are 2.039(1) and 2.037(1) Å. All the complexes have octahedral geometry around the Tc atom, with N-bonded isothiocyanato ligands. Important distortions of the octahedron was observed in compound II, due to the bulkiness of the four dimethylphenylphosphine ligands located in the same coordination plane. An important tetrahedral deformation of the plane containing the Tc and the four P atoms was observed.