Syntheses of new ionic technetium(III) complexes containing four monodentate phosphine ligands. Crystal structures of trans-[Tc(PMe2Ph)4Cl2]PF6, trans-[Tc(PMe3)4Cl2]BPh4, and trans-[Tc(PMe3)4Cl2]PF6.
New ionic technetium complexes of the type trans-[Tc(PR3)4Cl2]+ are synthesized by various methods. The simplest method is the reaction of [TcO4]- with the phosphine in methanol in the presence of a chloride salt. Compounds containing PMe2Ph and PMe3 are synthesized and characterized by crystallographic methods. The complexes containing the less bulky phosphine can be prepared from complexes containing the bulker phosphine. The compounds are paramagnetic, with two unpaired electrons. The complexes studied by X-ray diffraction methods are the trans isomers. [Tc(PMe2Ph)4Cl2]PF6 crystallizes in the monoclinic space group P2(1)/c, with a = 11.511(2) A, b = 26.713(7) A, c = 12.688(3) A, beta = 92.79(1) degrees, Z = 4, and R1 = 0.0574. [Tc(PMe3)4Cl2]BPh4 (II) crystallizes in the orthorhombic space group Pbcn, with a = 18.213(5) A, b = 22.950(5) A, c = 19.428(6) A, Z = 8, and R1 = 0.0691. [Tc(PMe3)4Cl2]PF6 crystallizes in the monoclinic space group P2(1)/c, with a = 18.152(7) A, b = 16.838(9) A, c = 18.090(6) A, beta = 106.63(1) degrees, Z = 8, and R1 = 0.0670. The compounds all have octahedral coordination, but an important tetrahedral deformation of the plane containing the Tc and the four P atoms is observed in each case. In II, the two independent Tc atoms are both located on 2-fold axes.