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)(2)Ph)(4)(NCS)(2) and Tc(P(OCH3)Ph-2)(4)(NCS)(2)center dot 1/2CH(2)Cl(2)

Three mixed-ligand neutral technetium complexes containing monodentate phos phine and isothiocyanato ligands have been synthesized and studied by cryst allographic 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 ar e 2.519(3) Angstrom while the Tc-N bonds are 1.991(6) and 2.003(6) Angstrom . Two Tc(II) compounds containing tetrasubstituted phosphine ligands were a lso characterized by X-ray diffraction methods. In trans-Tc(P(CH3)(2)Ph)(4) (NCS)(2) (II), the Tc atom is located on a twofold axis. The Tc-P bond dist ances are 2.429(2) and 2.482(2) Angstrom while the Tc-N bonds are 2.052(6) Angstrom. In trans-Tc(P(OCH3)Ph-2)(4)(NCS)(2). 1/2CH(2)Cl(2), the Tc-P bond distances vary between 2.423(1) and 2.442(1) Angstrom, while the Tc-N bond s are 2.039(1) and 2.037(1) Angstrom. All the complexes have octahedral geo metry around the Tc atom, with N-bonded isothiocyanato ligands. Important d istortions of the octahedron was observed in compound II, due to the bulkin ess of the four dimethylphenylphosphine ligands located in the same coordin ation plane. An important tetrahedral deformation of the plane containing t he Te and the four P atoms was observed. (C) 2000 Elsevier Science S.A. All rights reserved.