Synthesis of a Novel Class of Trigonal Bipyramidal Nitrido Tc(V) Complexes with Phosphino−Thiol Ligands. Crystal Structure of [^99gTc(N)(L¹)₂] [L¹ = 2-(Diphenylphosphino)ethanethiolato] and [^99gTc(N)(L⁵)₂] [L⁵ = 2-(Ditolylphosphino)propanethiolato]

Reactions of the precursor complexes [^99gTc(N)Cl₂(PPh₃)₂] and [^99gTc(N)Cl₄]^- with phosphine−thiol ligands (HLⁿ) of the type R₂PCH₂CH₂SH (R = phenyl, methoxypropyl), R₂‘PCH₂CH₂CH₂SH (R‘ = phenyl, tolyl), and R₂‘ ‘P-o-C₆H₄SH (R‘ ‘ = phenyl) afforded the five-coordinated, disubstituted nitrido technetium(V) complexes [^99gTc(N)(Lⁿ)₂]. The complexes were characterized by elemental analysis, ¹H and ³¹P NMR spectroscopy, FT IR, and positive FAB MS spectra. Structural characterization of [^99gTc(N)(L¹)₂] (1) [HL¹ = (C₆H₅)₂PCH₂CH₂SH] and [^99gTc(N)(L⁵)₂] (5) [HL⁵ = (o-CH₃C₆H₄)₂PCH₂CH₂CH₂SH] showed that the bidentate phosphino−thiol ligands are coordinated to the technetium center through the neutral phosphorus atom and the deprotonated thiol sulfur atom. These complexes possess an uncommon trigonal bipyramidal geometry with the two phosphorus atoms occupying the two transaxial positions and the two sulfur atoms on the equatorial plane along with the nitrido nitrogen atom. Compound 1 crystallizes in the monoclinic space group C2/c, a = 24.84(2) Å, b = 7.327(6) Å, c = 31.52(2) Å, β = 111.06(10)°, and Z = 8. Compound 5 crystallizes in the monoclinic space group P2₁/n, a = 11.090(1) Å, b = 14.387(2) Å, c = 11.087(1) Å, β = 113.62(1)°, and Z = 2.