Molecular and crystal structure of a mixed-phosphine ligand Tc(II) complex, Tc(PMe2Ph)2(DMPE)Cl2

The reaction of Tc(PMe2Ph)3Cl3 with an excess of bis(dimethylphosphino)ethane (DMPE) in ethanol solution produced a yellow compound, which was identified by X-ray diffraction methods as a mixed-ligand Tc(II) complex, Tc(PMe2Ph)2(DMPE)Cl2. The compound crystallizes in the P21/c space group with a = 12.899(6), b = 13.142(8), c = 19.088(9) A, β = 121.13(3)°, V = 2770(2) A3, Z = 4, R = 0.061, and Rw = 0.051. The geometry around the Tc atom is octahedral with the chloro ligands trans to each other, while the two PMe2Ph ligands are in cis positions. The Tc—Cl bond distances are 2.431 (5) and 2.431 (5) A while the Tc—P bond lengths are 2.434(4) and 2.435(4) A for PMe2Ph and 2.400(4) and 2.398(4) A for the bidentate DMPE ligand. An increase of multiple bonding of the Tc—P bond, as the oxidation state of Tc decreases, is suggested.