Technetium complexes labelled

Technetium is usually supplied in the form of heptavalent pertechnetate. Consequently, the syntheses of technetium complexes is necessarily accompanied by the reduction of pertechnetate. When concentrated hydrochloric acid is employed as a reductant, tetrachlorooxotechnetate(V) complexes can easily be obtained. A further reduction procedure is required to obtain hexachlorotech-netate(IV). Using these complexes, a number of technetium complexes have been synthesized by ligand substitution. The importance of preparative substitution reactions also increases in the light of the design and preparation of radiopharmaceuticals labelled with 99mTc and 188Re. 

The technitium +4 is then used to form the labelled organometallic technetium complexes that are absorbed in specific organs in the body. Many examples of this use of tin in the preparation of labelled technetium derivatives are given in a review by Noronha60. 

Waibel, R., R. Alberto, J. Willuda, R. Finnern, R. Schibli, A. Stichelberger, A. Egli, U. Abram, J.P. Mach, A. Pluckthun, and P.A. Schubiger, Stable one-step technetium-99m labeling of His-tagged recombinant proteins with a novel Tc (I)-carbonyl complex. Nat Biotechnol, 1999.17(9) 897-901. 

K. Hashimoto and K. Yoshihara, Rhenium Complexes Labeled with 186/188Re for Nuclear Medicine, in Technetium and Rhenium, Their Chemistry and its Applications (Topics in Current Chemistry, Vol. 176), eds. K. Yoshihara and T. Omori, Springer-Verlag, Berlin, 1996, p.275. 

PA. Stable one-step technetium-99m labeling of His-tagged recombinant proteins with a novel Tc(I)-carbonyl complex. Nat. Biotechnol. 1999 17 897-901. 

Deutsch E, Elder RC, Laarge BA et al (1978) Structural characterization of a bridged technetium-99-tin-dimethylglyoxime complex implication for the technetium-99m-labeled radiopharmaceuticals prepared by tin(II) reduction of pertechnetate. Proc Natl Acad Sci USA 73 653-660 Deutsch E, Glavan KA, Sodd VJ et al (1981) Cationic Tc-99m complexes as potential myocardial imaging agents. J Nucl Med 22 897-907... 

Loberg MD, Fields AT (1978) Chemical structure of technetium-99m-labeled N-(2,6-dimethyl-phe-nylcarbamoylmethyl)-iminodiacetic acid ( Tc-HIDA). Int J Appl Radiat Isot 29 167-173 March A, Garuti P, Duatti A et al (1990) Synthesis of technetium(V)-nitrido complexes with chelating amines a novel class of monocationic, octahedral complexes containing the [Tc = N] core. Crystal structures of [TcN(en)2Cl] (en = ethylenediamine) and [TcN(tad)Cl] (tad = 1,5,8,12-tet-raazadodecane). Inorg Chem 29 2091-2096... 

Srivastava SC, Meinken G, Smith TD, Richards P (1977) Problems associated with stannous " Tc-radiopharmaceuticals. Int J Appl Radial Isot 28 83-95 Subramanian G, McAfee JG, Bell EG, Blair RJ, Mara RE, Relston PH (1972) " Tc-labeled polyphosphates as skeletal imaging agent. Radiology 102 701-704 Subramanian G, McAfee JG, Blair RJ, Kallfelz FA, Thomas ED (1975) Technetium-99m methylene diphosphonate - a superior agent for skeletal imaging comparison with other technetium complexes. J Nucl Med 16 744-755... 

Horseradish peroxidase, 704 Human serum albumin technetium-99 labelled lung profusion techniques, 994 Humboltine structure, 849 Humic acids metal complexes geochemistry, 857-861 minerals, 849 stability, 859... 

At the same time that new instruments, such as the Anger camera, were being invented, chemists were developing technetium-99m labeled tracers, based on the reduction of sodium pertechnetate to technetium-tin complexes, the latter being a more useful diemical form for labeling molecules. Radionuclide generators in which molybdenum-99 decayed to technetium-99m made radiotracers readily available in nuclear medicine clinics in hospitals. One after the other new tests were invented and soon put into clinical practice. 

Despite its limited crystal field stabilization, the d complex bis(4-chloroben-zenethiolato)bis(l,2-bis dimethylphosphino ethane)technetium(II), (20), undergoes relatively slow trans to cis isomerization, with a rate constant of 1.6 x s in dichloromethane at ambient temperature. The low-spin d complex [Tc(acac)3] shows a similar reactivity with respect to exchange with " C-labeled acac to [Cr(acac)3]. Activation parameters for the technetium complex are AFT = 119 kJ mol" and A5 = -27 J mol" in acetylacetone. ... 

---