Reactions of pertechnetate anion with triphenylphosphine. Molecular structure (at –100 °C) of (1,1-dimethyl-3-oxobutyl)triphenylphosphonium pentachloro(triphenylphosphine)technetate(IV)

Abstract

The reactions of the [TcO₄]^– anion with PPh₃ in various concentrations of HCl are reported. [TcCl₄(PPh₃)₂], [TcCl₅(PPh₃)]^–, and [TcCl₆]^2– were obtained and the anionic complexes were isolated with cations such as [PPh₃H]⁺, [AsPh₄]⁺, or [Ph₃PC(Me)₂CH₂COMe]⁺. The crystal structure of the title complex was determined at –100 °C from 1 761 independent reflections and refined to R= 0.065. Crystals are monoclinic, space group P2₁/n, a= 21.909(4), b= 18.963(4), c= 9.896(3)Å, β= 103.05(5)°, and Z= 4. The structure consists of well separated units of octahedral [TcCl₅(PPh₃)]^– anions, and tetrahedral phosphonium cations, in which the phenyl groups are in a ′ propeller ′ configuration around P. Selected bond distances and angles are Tc–Cl (mean) 2.34(1), Tc–P 2.57(1)Å, Cl–Tc–Cl (mean) 90.7(4), Cl–Tc–P 88.7(4)°.