Synthesis and Characterization of Novel Trigonal Bipyramidal Technetium(III) Mixed-Ligand Complexes with SES/S/P Coordination (E = O, N(CH<sub>3</sub>), S)

Pietzsch, Hans‐Jürgen; Tisato, Francesco; Refosco, Fiorenzo; Leibnitz, P.; Drews, A.; Seifert, Stefan; Spies, Hartmut

doi:10.1021/ic000828m

Cited by 22 publications

(14 citation statements)

References 26 publications

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“…While the latter Tc–P bond lengths are in the normal range for Tc–P single bonds, the Tc–P4 bond is among the shortest experimentally determined Tc–P distances . Only for the 16e – compound [Tc I (dppe) 2 Cl] and for a few Tc(III) complexes Tc–P bond lengths shorter than 2.3 Å have hitherto been reported. ,− The positions of the hydrido ligands have been determined from the final Fourier maps of the refinement of the crystal data and Tc–H bond lengths of 1.54(2), 1.55(4), and 1.64(5) Å have been derived. It is known that M–H bond lengths derived from X-ray diffraction experiments are commonly too short due to the elusive physical nature of the hydrido ligand electrons in such complexes, but no neutron diffraction data on technetium hydrido complexes have hitherto been reported.…”

Section: Resultsmentioning

confidence: 99%

Technetium Hydrides Revisited: Syntheses, Structures, and Reactions of [TcH₃(PPh₃)₄] and [TcH(CO)₃(PPh₃)₂]

2021

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Optimized synthetic approaches to [TcH 3 (PPh 3 ) 4 ] (1) and mer-trans-[TcH(CO) 3 (PPh 3 ) 2 ] (5) as key compounds of the technetium hydrido chemistry are reported. They give access to pure and stable samples of the complexes. The solid-state structures of the two title compounds have been determined. Reactions of [TcH 3 (PPh 3 ) 4 ] with monodentate basic phosphines such as PMe 2 Ph or PMe 3 lead to mixtures o f m i x e d -p h o s p h i n e c o m p l e x e s o f t h e c o m p o s i t i o n s [TcH 3 (PR 3 ) n (PPh 3 ) 4−n ] (n = 1−3), from which the mixed-phosphine trihydride complex [TcH 3 (PPh 3 ) 2 (PMe 3 ) 2 ] (2) could be isolated. Spectroscopic data and DFT calculations suggest a fluxional structure between a capped trigonal prism and a pentagonal bipyramid. Reactions of the monohydride mer-trans-[TcH(CO) 3 (PPh 3 ) 2 ] (5) with HX (X = Cl, Br, I) give [TcX(CO) 3 (PPh 3 ) 2 ] (6) complexes in good yields, while mer-trans-[Tc{η 1 -O(CR)O}(CO) 3 (PPh 3 ) 2 ] (7) or cis−trans-[Tc{η 2 -OO(CR)}(CO) 2 (PPh 3 ) 2 ] (8) complexes are formed with carboxylic acids depending on the substituent R and the conditions applied. Chelate formation of the formato ligand can also be obtained by thermal decarbonylation of the isolated mertrans-[Tc(η 1 -O(CH)O)(CO) 3 (PPh 3 ) 2 ] (7a) complex. The latter reaction is reversible, and the tricarbonyl compound is reformed when [Tc{η 2 -OO(CH)}(CO) 2 (PPh 3 ) 2 ] (8a) is exposed to CO gas. Reactions of [TcH(CO) 3 (PPh 3 ) 2 ] (5) with phenyl seleninic acid (PhSeOOH) in methanol give the tetranuclear cluster [{Tc(CO) 3 } 3 (μ 3 -OH)(μ 2 -O(SePh)O) 3 {Tc(CO) 3 }] (10) and a small amount of the bridged dinuclear oxalato complex [Tc 2 (CO) 6 (ox)(OPPh 3 ) 2 ] (11). The latter compound is the result of a complex reaction, which involves a metal-induced oxidation of methanol to formate and a subsequent C−C coupling of two formato ligands. The plausibility of the proposed mechanism is supported by the fact that the dimeric oxalato complex is much more efficiently formed when the formato complex [Tc{η 1 -O(CH)O}(CO) 3 (PPh 3 ) 2 ] (7a) is directly reacted with PhSeOOH. Exclusively the monomeric oxalato complex [Tc(η 2 -oxH)(CO) 2 (PPh 3 ) 2 ] ( 12) is formed during a reaction of mer-trans-[TcH(CO) 3 (PPh 3 ) 2 ] (5) with oxalic acid. The remaining proton of the Hox − ligand of [Tc(η 2 -oxH)(CO) 2 (PPh 3 ) 2 ] (12) can be removed by NEt 3 , and the ion pair (HNEt 3 )[Tc(η 2 -ox)(CO) 2 (PPh 3 ) 2 ] (13) is formed.

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Section: Resultsmentioning

confidence: 99%

Technetium Hydrides Revisited: Syntheses, Structures, and Reactions of [TcH₃(PPh₃)₄] and [TcH(CO)₃(PPh₃)₂]

2021

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“…6, 7 Other mixed ligand systems have been proposed but are less convenient. 8 Lipophilic Tc() complexes with umbrella-like tetradentate NSSS ligands and monodentate isocyanides showed excellent stability in vitro towards plasma components. 9- 11 The hynic approach can also be considered as a kind of mixed ligand approach.…”

Section: Introductionmentioning

confidence: 97%

A new [2 + 1] mixed ligand concept based on [^99(m)Tc(OH₂)₃(CO)₃]⁺: a basic study

et al. 2004

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Mixed ligand fac-tricarbonyl complexes of the general formula [M(L1)(L2)(CO)3](M = Re, 99(m)Tc, L1= imidazole, benzyl isocyanide, L2 = 1H-imidazole-4-carboxylic acid, pyridine-2,4-dicarboxylic acid, pyridine-2,5-dicarboxylic acid) have been prepared starting from the precursors [M(OH2)3(CO)3]+. The complexes can be obtained in good yield and purity in a two-step procedure by first attaching the bidentate ligand followed by addition of the monodentate. 99mTc compounds can also be prepared at the tracer level in one-pot procedures with L1 and L2 being concomitantly present. This [2 + 1] approach allows the labeling of bioactive molecules containing a monodentate or a bidentate donor site. Examples given in here are N-(tert-butoxycarbonyl)glycyl-N-(3-(imidazol-1-yl)propyl)phenylalaninamide, 5-((3-(imidazol-1-yl)propyl)aminomethyl)-2'-deoxyuridine and 4-(5-isonitrilpentyl)-1-(2-methoxyphenyl)-piperazine as L1 and N-((6-carboxypyridine-3-yl)methyl)glycylphenylalanine as L2. The corresponding second ligand can be used to influence the physico-chemical properties of the conjugate. The crystal structures of [99Tc(OH2)(imc)(CO)3], [Re(OH2)(2,4-dipic)(CO)3], [Re(bic)(2,4-dipic)(CO)3] and [Re(im)(2,5-dipic)(CO)3] are reported.

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“…Another type of neutral Tc(III) complexes derived from the reaction of oxo-Tc(V) “3+1“ precursors with tertiary phosphines, namely, the “3+1+1” complexes of general formula [M(PR 3 )(SES)(SR)] (SES = tridentate dithiol ligand; E = S, NR, O), are still unstable against cysteine and GSH and, sometimes, re-oxidize to the original starting material ( , ). Stability of this class of compounds can be enhanced by combining the monodentate ligands, i.e., tertiary phosphine and thiol, into a bidentate P,S phosphinothiol to produce “3+2” Tc(III) mixed-ligand complexes of the type [Tc(SES)(R 2 PS)].…”

Section: Introductionmentioning

confidence: 99%

“…UV/vis spectra were recorded on a SPECORD S10 spectrometer from Carl Zeiss Jena. Proton, 13 C, and 31 P NMR spectra were collected on a Bruker 300 instrument, using SiMe 4 as internal reference ( 1 H and 13 C) and 85% aqueous H 3 PO 4 as external reference ( 31 P). Samples were dissolved in deuterated chloroform at a concentration of ca.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Biological Evaluation of Technetium(III) Complexes with Tridentate/Bidentate S,E,S/P,S Coordination (E = O, N(CH₃), S): A Novel Approach to Robust Technetium Chelates Suitable for Linking the Metal to Biomolecules

et al. 2002

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A novel type of mixed-ligand Tc(III) complexes, [Tc(SCH(2)CH(2)-E-CH(2)CH(2)S)(PR(2)S)] (E = S, N(CH(3)); PR(2)S = phosphinothiolate with R = aryl, alkyl) is described. These "3+2"-coordinated complexes can be prepared in a two-step reduction/substitution procedure via the appropriate chloro-containing oxotechnetium(V) complex [TcO(SES)Cl] [E=S, N(CH(3)]. Tc(III) compounds have been fully characterized both in solid and solution states and found to adopt the trigonal-bipyramidal coordination geometry. The equatorial trigonal plane is formed by three thiolate sulfur atoms, whereas the phosphorus of the bidentate P,S ligand and the neutral donor of the tridentate chelator occupy the apical positions. The (99)Tc(III) complexes have been proven to be identical with the (99m)Tc agents prepared at the no-carrier-added level by comparison of the corresponding UV/vis and radiometric HPLC profiles. Challenge experiments with glutathione clearly indicate that this tripeptide has no effect on the stability of the (99m)Tc complexes in solutions. Biodistribution studies have been carried out in rats at 5 and 120 min postinjection. The substituents at the bidentate P,S ligand significantly influence the biodistribution pattern. Remarkable differences are observed especially in brain, blood, lungs, and liver. All the complexes are able to penetrate the blood-brain barrier of rats and showed a relatively fast washout from the brain.

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Synthesis and Characterization of Novel Trigonal Bipyramidal Technetium(III) Mixed-Ligand Complexes with SES/S/P Coordination (E = O, N(CH₃), S)

Cited by 22 publications

References 26 publications

Technetium Hydrides Revisited: Syntheses, Structures, and Reactions of [TcH₃(PPh₃)₄] and [TcH(CO)₃(PPh₃)₂]

Technetium Hydrides Revisited: Syntheses, Structures, and Reactions of [TcH₃(PPh₃)₄] and [TcH(CO)₃(PPh₃)₂]

A new [2 + 1] mixed ligand concept based on [^99(m)Tc(OH₂)₃(CO)₃]⁺: a basic study

Synthesis, Characterization, and Biological Evaluation of Technetium(III) Complexes with Tridentate/Bidentate S,E,S/P,S Coordination (E = O, N(CH₃), S): A Novel Approach to Robust Technetium Chelates Suitable for Linking the Metal to Biomolecules

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Synthesis and Characterization of Novel Trigonal Bipyramidal Technetium(III) Mixed-Ligand Complexes with SES/S/P Coordination (E = O, N(CH3), S)

Cited by 22 publications

References 26 publications

Technetium Hydrides Revisited: Syntheses, Structures, and Reactions of [TcH3(PPh3)4] and [TcH(CO)3(PPh3)2]

Technetium Hydrides Revisited: Syntheses, Structures, and Reactions of [TcH3(PPh3)4] and [TcH(CO)3(PPh3)2]

A new [2 + 1] mixed ligand concept based on [99(m)Tc(OH2)3(CO)3]+: a basic study

Synthesis, Characterization, and Biological Evaluation of Technetium(III) Complexes with Tridentate/Bidentate S,E,S/P,S Coordination (E = O, N(CH3), S): A Novel Approach to Robust Technetium Chelates Suitable for Linking the Metal to Biomolecules

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Synthesis and Characterization of Novel Trigonal Bipyramidal Technetium(III) Mixed-Ligand Complexes with SES/S/P Coordination (E = O, N(CH₃), S)

Technetium Hydrides Revisited: Syntheses, Structures, and Reactions of [TcH₃(PPh₃)₄] and [TcH(CO)₃(PPh₃)₂]

Technetium Hydrides Revisited: Syntheses, Structures, and Reactions of [TcH₃(PPh₃)₄] and [TcH(CO)₃(PPh₃)₂]

A new [2 + 1] mixed ligand concept based on [^99(m)Tc(OH₂)₃(CO)₃]⁺: a basic study

Synthesis, Characterization, and Biological Evaluation of Technetium(III) Complexes with Tridentate/Bidentate S,E,S/P,S Coordination (E = O, N(CH₃), S): A Novel Approach to Robust Technetium Chelates Suitable for Linking the Metal to Biomolecules