Synthesis and characterization of technetium(V) complexes with amine, alcoholate, and chloride ligands

Pearlstein, Ronald M.; Lock, C. J. L.; Faggiani, R.; Costello, Catherine E.; Zeng, Chen Hui; Jones, Alun G.; Davison, Alan

doi:10.1021/ic00287a010

Cited by 29 publications

(5 citation statements)

References 2 publications

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“…The MM force field yields the following energetics ordering: F < D < E . Submission of these structures to further refinement by PM3(tm)-GA geometry optimization (singlet spin state) indicates that geometry F is the electronically preferred one, consistent with the X-ray crystallographic evidence for GELFAE . The SEQM-derived energy ordering of the geometric isomers is the same as that of the MM: F < D (by 4 kcal/mol) < E (14 kcal/mol above isomer F ).…”

Section: Resultssupporting

confidence: 64%

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De NovoStructural Prediction of Transition Metal Complexes: Application to Technetium

et al. 2002

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De novo structural prediction of transition metal complexes is investigated. Technetium complexes are chosen given their importance in medical imaging and nuclear waste remediation and for the chemical diversity they display. A new conformational searching algorithm (LIGB) for transition metals is described that allows one to search for different conformational and geometric isomers within a single simulation. In the preponderance of cases, both conformational searching techniques (LIGB and high-temperature molecular dynamics/simulated annealing) provide comparable results, while LIGB is superior for macrocyclic complexes. A genetic algorithm-optimized PM3(tm) parametrization for Tc is compared with the standard implementation and found to yield a significant improvement in predictive ability for the most prevalent Tc structural motifs. The utility of a coupled molecular mechanics-semiempirical quantum mechanics protocol is demonstrated for very rapid, efficient, and effective de novo prediction of transition metal complex geometries.

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Section: Resultssupporting

confidence: 64%

“…d. GELFAE (Chloro-(1,2-ethanediolato)-oxo-(1,10-phenanthroline- N , N ‘ )-technetium(V)). For this complex, three groups of conformational isomers ( D − F ) are expected and found from the MM conformational search. The MM force field yields the following energetics ordering: F < D < E .…”

Section: Resultsmentioning

confidence: 99%

De NovoStructural Prediction of Transition Metal Complexes: Application to Technetium

et al. 2002

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“…Altematively, Tc complexes can be prepared by ligand substitution on an easily accessible precursor. Many examples can be cited, as [TcOCL,]-for Tc(V) complexes [3,4], [TcBrg]"-for Tc(IV) complexes [5] and [TcCtu)«]'"" (tu = thiourea) for Tc(in) ones [6,7]. If the incoming ligand is able to stabilize this Tc oxidation State, use of this substitution route allows to control the final oxidation State of the Tc product.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Chemical Studies on Tc(III) Complexes Containing Polyaminocarboxylic Acids

et al. 1998

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Tc chemistry / Tc(UI) complexes / Polyaminocarboxylic acids SununaryTc(m)-edta (edta = eüiylenediaminetetraacetate), Tc(m)-dtpa (dtpa = dietiiylenetriaminepentaacetate) and Tc(III)-mebrofenin (mebrofenin = 3-bromo-2,4,6-trimetiiylacetanilideiininodiacetate) complexes were prepared by ligand substitution reactions on hexalds(thiourea)teciinetium(III) cation with tlie polycarboxylates. By a combination of different teciiniques (UV-Vis, IR and *H-NMR spectroscopy, Tc elemental analyses and cerimetric titrations) it was concluded that 1:1 complexes are formed with edta and dtpa while mebrofenin adopts a 2:1 (ligand to metal) stoichiometry. Complementary, molecular mechanics calculations were performed to analyze the spatial arrangement of the molecules. The stability of the Tc(III) complexes was studied in aqueous Solution by paper chromatography, paper electrophoresis and cyclic voltammetry. The chelates are rather stable, in particular when compared with the precursor.

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“…Furthermore, the energy of the emitted photons of 140 keV is sufficient to study organs lying deep in the body and can be collimated so as to be detected effectively with NaI(T1) scintillation counters. Finally, the relatively stable 99m Tc isotope may be used to develop technetium chemistry and to model technetium radiopharmaceuticals ( , ).…”

Section: Introductionmentioning

confidence: 99%

N,N-Bis(2-mercaptoethyl)methylamine: A New Coligand for Tc-99m Labeling of Hydrazinonicotinamide Peptides

et al. 2005

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Hydrazinonicotinamide (HYNIC) forms stable coordination complexes with Tc-99m when reacted with Tc(V)oxo species such as Tc-mannitol or other Tc-polyhydric complexes. However, radio-HPLC of [Tc-For-MLFK-HYNIC] labeled via Tc-polyhydric ligands demonstrated multiple radiochemical species each with unique biodistribution patterns. This is likely due to the fact that Tc can bind to the hydrazino moiety, as well as polyhydric ligands, in a variety of coordination geometries. Tridentate ligands, such as bis(mercaptoethyl)methylamine (NS2), may constrain the possible coordination geometries and improve overall stability. To investigate this, we synthesized NS2, converted the [Tc-mannitol-For-MLFK-HYNIC] to the corresponding NS2-containing complex [Tc-NS2-For-MLFK-HYNIC], and compared its infection imaging and biodistribution properties with [Tc-mannitol-For-MLFK-HYNIC]. Conversion to the NS2 complex was confirmed by HPLC which showed a single unique hydrophobic species with retention time greater than the [Tc-mannitol-For-MLFK-HYNIC] complex. Imaging experiments with both preparations were performed in rabbits with E. coli infections in the left thigh. Tissue radioactivity measurements demonstrated that compared to Tc-mannitol-peptide, accumulation of Tc-NS2-peptide was lower in blood, heart, and normal muscle and higher in spleen, infected muscle, and pus (p < 0.01). These results indicate that the Tc-NS2-peptide complex is chemically more homogeneous and exhibits improved infection localization and biodistribution properties. In an effort to model the interactions of the metal-HYNIC core with NS2 and related ligand types, the reactions of [ReCl3(NNC5H4NH)(NHNC5H4N)] and [99TcCl3(NNC5H4NH)(NHNC5H4N)], effective structural analogues for the [M(NNC5H4NH(x))2] core, with NS2, C5H3N-2,6-(CH2SH)2, O(CH2CH2SH)2, and S(CH2CH2SH)2 were investigated and the compounds [M[CH3N(CH2CH2S)2](NNC5H4N)(NHNC5H4N] (M = 99Tc (5a), Re (5b)), [Re[C5H3N-2,6-(CH2S)2](NNC5H4N)(NHNC5H4N)].CH2Cl2.0.5MeOH (7), [Re[SCH2CH2)2O] (NNC5H4N)(NHNC5H4N)] (8), and [Re[(SCH2CH2)2S](NNC5H4NH)(NHNC5H4N)]Cl (9) were isolated. Similarly, the reaction of [ReCl3(NNC5H4NH)(NHNC5H4N)] with the bidentate ligands pyridine-2-methanethiol and 3-(trimethlysilyl)pyridine-2-thiol led to the isolation of [ReCl(C5H4N-2-CH2S) (NNC5H4N)(NHNC5H4N)] (10) and [Re(2-SC5H3N-3-SiMe3)2 (NNC5H4N)(NHNC5H4N)] (11), respectively, while reaction with N-methylimidazole-2-thiol yielded the binuclear complex [Re(OH)Cl(SC3H2N2CH3)2(NNC5H4N)2 (NHNC5H4N)2] (12). The analogous metal-(HYNIC-OH) precursor, [ReCl3[NNC5H3NH(CO2R)] [NHNC5H3N(CO2R)]] (R = H, 13a; R = CH3, 13b) has been prepared and coupled to lysine to provide [RCl3[NNC5H3NH(CONHCH2CH2CH2CH2CH(NH2)CO2H)] [NHNC5H3NH(CONHCH2CH2CH2CH2CH(NH2)CO2H)]].2HCl (14.2HCl), while the reaction of the methyl ester 13b with 2-mercaptopyridine yields [Re(2-SC5H4N)2[NNC5H3N(CO2Me)][NHNC5H3N(CO2Me)]] (15). While the chemical studies confirm the robustness of the M-HYNIC core (M = Tc, Re) and its persistence in ligand substitution reactions at adjacen...

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Synthesis and characterization of technetium(V) complexes with amine, alcoholate, and chloride ligands

Cited by 29 publications

References 2 publications

De NovoStructural Prediction of Transition Metal Complexes: Application to Technetium

De NovoStructural Prediction of Transition Metal Complexes: Application to Technetium

Preparation and Chemical Studies on Tc(III) Complexes Containing Polyaminocarboxylic Acids

N,N-Bis(2-mercaptoethyl)methylamine: A New Coligand for Tc-99m Labeling of Hydrazinonicotinamide Peptides

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