The synthesis and characterization of a cationic technetium(V) phenylimido complex. The X-ray crystal structure of [TcCl 2(NPh)(PMe 2Ph) 3](BPh 4)

Abstract

The reaction of the neutral Tc(V) phenylimido complex [TcCl 3(NPh)(PPh 3) 2] with excess PMe 2Ph in refluxing MeOH gives the cationic, tris-dimethylphenylphosphine complex [TcCl 2(NPh)(PMe 2Ph) 3] +, which is isolated as the tetraphenylborate salt. The IR spectrum of the crystalline product shows a medium intensity band at 1102 cm −1 which is assigned to ν(TcN) from the phenylimido core. The 1H NMR spectrum of the diamagnetic complex shows a series of multiplets in the aryl region and three distinct signals near 2 ppm from the phosphine methyl groups. The X-ray crystal structure, which is the first for a cationic technetium organoimido complex, shows a meridional arrangement of phosphine ligands with a chloride ligand coordinated trans to the phenylimido unit. The TcN bond length of 1.711(2) Å is consistent with the dianionic nature of the organonitrogen core. The TcNC bond angle of 178.8(2)° reflects the sp hybridization of the phenylimido nitrogen atom. The coordination geometry is best described as a distorted octahedron. Crystal data for C 54H 58BCl 2NP 3Tc: triclinic space group P 1, a = 11.337(2), b = 13.054(3), c = 17.854(4) A ̊ , α = 72.36(3), β = 88.51(3), γ = 89.76(3)°, V = 2517.2(13) A ̊ 3, with D calc = 1.311 g cm −3 . Structure solution based on 9986 observed reflections converged at R = 3.65%, R w = 5.43%, GOF = 1.82.