Metal-metal multiply-bonded complexes of technetium. 6. A μ, η1, η2-CH 3CN complex prepared via reductive cleavage of the electron-rich TcTc triple bond in decakis-acetonitrile ditechnetium tetrafluoroborate

Abstract

Chemical reduction of the dinuclear cation [Tc 2(CH 3CN) 10] 4+ in acetonitrile results in scission of the metal-metal triple bond to produce two Tc(CH 3CN) 5 fragments linked together via a μ, η 1, η 2-acetonitrile ligand. The Tc(I)-Tc(II) mixed-valent compound [Rc 2( μ, η 1, η 2-CH 3CN) (CH 3CN) 10] [BF 4] 3 ( 1) was isolated as a red-brown solid in 70% yield using cobaltocene as a reductant. Lower yields (53%) were obtained when the reduction was carried out with zinc. The crystal structure of 1·0.83 CH 3CN reveals that the Tc atoms are separated by a distance of 4.04(2) Å consistent with the complete lack of any metal-metal bonding. Compound 1 has been fully characterized by a variety of spectroscopic techniques including 1H NMR, UV-Vis and IR spectroscopies as well as cyclic voltammetry. Crystal data at −60°C for 1·0.83CH3CN:triclinic space group P ( No. 2), a = 12.658(4), b = 16.513(4), c = 19.495(6) A ̊ , α = 90.21(2), β = 99.33(3), γ = 90.18(3)°, V = 4020(2) A ̊ 3, Z = 4 .