Preparation of No-Carrier-Added Technetium-99m Complexes via Metal-Assisted Cleavage from a Solid Phase

A novel method for the preparation of no-carrier-added (nca) complexes [99mTc(CO)3L] (L = diethylenetriamine or picolylamine-N-acetic acid) is described. The ligands were covalently bound to a solid support of organic polymers via formation of a tertiary amine from the chelating unit. This C−N bond to the solid phase is selectively cleaved during the formation of the technetium complexes by intramolecular nucleophilic attack of a remaining hydroxy ligand to the α-carbon. The complex [99mTc(CO)3L] is released into solution while uncomplexed ligand and uncleaved complex remain solid-phase bound. High specific activity technetium complexes can then be isolated by simple filtration. Cleavage yield depends on temperature, pH, and ligand. Up to 50% release from the solid phase could be achieved under optimized conditions. Corresponding to the 99mTc concentration, free ligand is present in concentrations lower than 10-7 M. If a targeting vector is conjugated to these ligands, no-carrier-added radiopharmaceuticals can be prepared in that way

Synthesis and Properties of Boranocarbonate: A Convenient in Situ CO Source for the Aqueous Preparation of [^99mTc(OH₂)₃(CO)₃]⁺

Synthesis and Properties of Boranocarbonate:  A Convenient in Situ CO Source for the Aqueous Preparation of [99mTc(OH2)3(CO)3]+</sup

Preparation of No-Carrier-Added Technetium-99m Complexes via Metal-Assisted Cleavage from a Solid Phase

A novel method for the preparation of no-carrier-added (nca) complexes [99mTc(CO)3L] (L = diethylenetriamine or picolylamine-N-acetic acid) is described. The ligands were covalently bound to a solid support of organic polymers via formation of a tertiary amine from the chelating unit. This C−N bond to the solid phase is selectively cleaved during the formation of the technetium complexes by intramolecular nucleophilic attack of a remaining hydroxy ligand to the α-carbon. The complex [99mTc(CO)3L] is released into solution while uncomplexed ligand and uncleaved complex remain solid-phase bound. High specific activity technetium complexes can then be isolated by simple filtration. Cleavage yield depends on temperature, pH, and ligand. Up to 50% release from the solid phase could be achieved under optimized conditions. Corresponding to the 99mTc concentration, free ligand is present in concentrations lower than 10-7 M. If a targeting vector is conjugated to these ligands, no-carrier-added radiopharmaceuticals can be prepared in that way

Aqueous Synthesis of Derivatized Cyclopentadienyl Complexes of Technetium and Rhenium Directed toward Radiopharmaceutical Application

Half-sandwich complexes of the type [(RCOCp)M(CO)3] with M = Re and 99(m)Tc were synthesized from [M(OH2)3(CO)3]+ in water. The R group can be an organic residue or a receptor binding biomolecule with a spacer to cyclopentadienyl (Cp). This provides a general route to Cp complexes of technetium without the need for starting from [TcBr(CO)5]. The X-ray structure of [{C6H5CH2COC5H4}Tc(CO)3] has been elucidated. The compound crystallizes in the monoclinic space group P21/c with a = 16.1454(9), b = 7.6300(6), and c = 12.3922(7) Å and β = 107.792(6)°. We have chosen a serotonergic receptor ligand (WAY) as an example for the derivatization of Cp with a bioactive molecule. WAY is linked to Cp by an aliphatic chain of variable length. The half-sandwich complexes were prepared from water and organic solvents. The structure of [(WAY4−Cp)Re(CO)3] could be elucidated. The compound crystallizes in the monoclinic space group P21/c with a = 15.7112(6), b = 6.8775(3), and c = 25.5217(12) Å and β = 103.778(5)°. Quantification of inhibition constants gave a clear structure−activity relationship. A single methylene group between the receptor binding site and the half-sandwich complex gave an IC50 of 217 nM for HT1A, whereas a butylene linker resulted in retention of the inhibition constant with an IC50 of 6 nM with respect to underivatized WAY. For use as radiopharmaceuticals, the compounds have also been prepared with 99mTc in quantitative yield

Re Tricarbonyl Complexes with Ligands Containing P,N,N and P,N,O Donor Atom Sets: Synthesis and Structural Characterization

The coordination chemistry of the heterofunctionalized phosphines HPN2 and H2PNO and of an analogue containing a relevant biomolecule, HPN-Pip (Pip = 4-(3-aminopropyl)-1-(2-methoxyphenyl)piperazine), was studied toward the synthon (NEt4)2[ReBr3(CO)3]. The complexes isolated, [Re(CO)3(κ3-PN2)], 3, [Re(CO)3Br(κ2-H2PNO)], 4, and [Re(CO)3Br(κ2-HPN-Pip)], 5, are the first examples of Re(I) compounds stabilized by such a combination of donor atoms. All of the compounds are neutral, but the phosphines, depending on the combination of atoms, act as monoanionic and tridentate (3) or as neutral and bidentate (4, 5). The characterization of 3−5 included IR, 1H NMR, and 31P NMR spectroscopy and X-ray crystallographic analysis. Colorless crystals of compounds 3 and 4 were obtained by slow evaporation of a methanolic solution of 3 and from a boiling acetonitrile solution of 4. Compound 3 crystallizes with two molecules of MeOH per asymmetric unit in the monoclinic space group P21/c, a = 10.1237(8) Å, b = 9.4959(4) Å, c = 28.365(2) Å, β = 98.707(9)°, V = 2695.4(3) Å3, Z = 4; 4 crystallizes in the triclinic space group P1̄, a = 10.0241(9) Å, b = 11.2060(10) Å, c = 13.0656(12) Å, α = 84.883(11)°, β = 71.163(10)°, γ = 63.650(9)°, V = 1241.19(19) Å3, Z = 2

Gold Complexes with Potentially Tri- and Tetradentate Phosphinothiolate Ligands

Reactions of [Au(PPh3)Cl], (Bu4N)[AuCl4] and the organometallic gold complex [Au(damp-C1,N)Cl2] (damp- = 2-(N,N-dimethylaminomethyl)phenyl) with the potentially tri- and tetradentate proligands PhP(C6H3−SH-2−R-3)2 (H2L1a, R = SiMe3; H2L1b, R = H) and P(C6H4−SH-2)3 (H3L2) result in the formation of mono- or dinuclear gold complexes depending on the precursor used. Monomeric complexes of the type [AuL1Cl] are formed upon the reaction with [Au(damp-C1,N)Cl2], but small amounts of dinuclear [AuL1]2 complexes with gold in two different oxidation states, +1 and +3, have been isolated as side-products. The dinuclear compounds are obtained in better yields from [AuCl4]-. A dinuclear complex having two Au(III) centers can be isolated from the reaction of [Au(PPh3)Cl] with H3L2, whereas from the reaction with H2L1b the mononuclear [Au(Ph3P)HL1b] is obtained, which contains a three-coordinate gold atom. Comparatively short gold−gold distances have been found in the dinuclear complexes (2.978(2) and 3.434(1) Å). They are indicative of weak gold−gold interactions, which is unusual for gold(III)

Synthesis and Properties of Boranocarbonate: A Convenient in Situ CO Source for the Aqueous Preparation of [^99mTc(OH₂)₃(CO)₃]⁺

Synthesis and Properties of Boranocarbonate:  A Convenient in Situ CO Source for the Aqueous Preparation of [99mTc(OH2)3(CO)3]+</sup

Aqueous Synthesis of Derivatized Cyclopentadienyl Complexes of Technetium and Rhenium Directed toward Radiopharmaceutical Application

Half-sandwich complexes of the type [(RCOCp)M(CO)3] with M = Re and 99(m)Tc were synthesized from [M(OH2)3(CO)3]+ in water. The R group can be an organic residue or a receptor binding biomolecule with a spacer to cyclopentadienyl (Cp). This provides a general route to Cp complexes of technetium without the need for starting from [TcBr(CO)5]. The X-ray structure of [{C6H5CH2COC5H4}Tc(CO)3] has been elucidated. The compound crystallizes in the monoclinic space group P21/c with a = 16.1454(9), b = 7.6300(6), and c = 12.3922(7) Å and β = 107.792(6)°. We have chosen a serotonergic receptor ligand (WAY) as an example for the derivatization of Cp with a bioactive molecule. WAY is linked to Cp by an aliphatic chain of variable length. The half-sandwich complexes were prepared from water and organic solvents. The structure of [(WAY4−Cp)Re(CO)3] could be elucidated. The compound crystallizes in the monoclinic space group P21/c with a = 15.7112(6), b = 6.8775(3), and c = 25.5217(12) Å and β = 103.778(5)°. Quantification of inhibition constants gave a clear structure−activity relationship. A single methylene group between the receptor binding site and the half-sandwich complex gave an IC50 of 217 nM for HT1A, whereas a butylene linker resulted in retention of the inhibition constant with an IC50 of 6 nM with respect to underivatized WAY. For use as radiopharmaceuticals, the compounds have also been prepared with 99mTc in quantitative yield

Re and Tc Complexes Containing B−H···M Agostic Interactions as Building Blocks for the Design of Radiopharmaceuticals

Re and Tc Complexes Containing B−H···M Agostic Interactions as Building Blocks for the Design of Radiopharmaceutical

Re and Tc Complexes Containing B−H···M Agostic Interactions as Building Blocks for the Design of Radiopharmaceuticals

Re and Tc Complexes Containing B−H···M Agostic Interactions as Building Blocks for the Design of Radiopharmaceutical