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]

Abstract

Reactions of the precursor complexes [(99g)Tc(N)Cl(2)(PPh(3))(2)] and [(99g)Tc(N)Cl(4)](-) with phosphine-thiol ligands (HL(n)()) of the type R(2)PCH(2)CH(2)SH (R = phenyl, methoxypropyl), R(2)'PCH(2)CH(2)CH(2)SH (R' = phenyl, tolyl), and R(2)' 'P-o-C(6)H(4)SH (R' ' = phenyl) afforded the five-coordinated, disubstituted nitrido technetium(V) complexes [(99g)Tc(N)(L(n)())(2)]. The complexes were characterized by elemental analysis, (1)H and (31)P NMR spectroscopy, FT IR, and positive FAB MS spectra. Structural characterization of [(99g)Tc(N)(L(1))(2)] (1) [HL(1) = (C(6)H(5))(2)PCH(2)CH(2)SH] and [(99g)Tc(N)(L(5))(2)] (5) [HL(5) = (o-CH(3)C(6)H(4))(2)PCH(2)CH(2)CH(2)SH] 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, beta = 111.06(10) degrees, and Z = 8. Compound 5 crystallizes in the monoclinic space group P2(1)/n, a = 11.090(1) Å, b = 14.387(2) Å, c = 11.087(1) Å, beta = 113.62(1) degrees, and Z = 2.

Characterisation via electrospray ionisation multistage mass spectrometry of three related series of nitrido technetium complexes containing phosphinothiolate and dithiocarbamate ligands

“…Because of our ongoing interest in the synthesis of 99 Tc‐complexes, we have recently prepared series of neutral and five‐coordinate nitrido‐containing species of general formula Tc(N)(PS) 2 , where PS represents a bidentate monoanionic phosphinothiolate ligand 3. Synthesis of 99m Tc analogs at the nano‐molar level and their subsequent biodistribution in rats indicated that 99m Tc(N)(PS) 2 agents were able to cross the intact BBB, but without showing accumulation in the cerebral cells (C. Bolzati, F. Tisato, et al ., manuscript in preparation).…”

“…The molecular structure of bis‐substituted Tc(N)(PS) 2 and Tc(N)(dtc) 2 complexes has already been fully elucidated 3, 5. It usually consists of distorted square pyramidal (sp) arrays with the nitride group at the apex and the four P 2 S 2 or S 4 donor atoms at the base of the pyramid, except for some Tc(N)(PS) 2 derivatives, for which sp has rearranged to the trigonal bipyramidal (tbp) fashion for steric reasons ( vide infra ).…”

“…Symmetric bis‐substituted compounds 1 – 6 were synthesised and purified according to literature methods,3, 9 whereas details of the synthesis and complete characterisation of mixed‐ligand compounds 7 – 9 will be published elsewhere.…”

Synthesis and biodistribution of novel 99mTc‐nitrido methylpiperidine dithioformate derivatives as potential brain imaging agents

“…12 In our laboratory, the synthesis and biodistribution of [ 99m TcN(RR'NCS 2 ) 2 ] complexes were investigated. [13][14][15][16][17][18][19] It was found that the brain uptakes and brain-to-blood ratios of these complexes were strongly affected by the substitution R and R 0 bound to the-NCS 2 moiety.…”

New Organometallic Technetium Complexes for Radiopharmaceutical Imaging

“…They can then be replaced via ligand exchange to give stronger multidentate chelators. Another core that merits attention is "[TcϵN] 2+ ", also with technetium in oxidation state +V and similar chemical behaviour in respect of aquo ions as in [Tc=O] 3+ [17][18][19][20]. Besides these two central moieties, the mixed-ligand [3+1] concept based on the [Tc=O] 3+ core is widely applied in research [21,22].…”