SYNTHESIS OF RADIOPHARMACEUTICALS BY THE REDUCTION OF 99mTcO4−: 99mTc-LABELLED HEART SCANNING AGENTS

Siegel, Jeffry A.; Deutsch, Edward

doi:10.1016/b978-0-12-040704-0.50026-0

Cited by 2 publications

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“…figure. Since the preparation of reduced 99mTc-radiopharmaceuticals is often effected by the tin(II) reduction of pertechnetate (11), it is likely that the Sn-O-Tc linkage is an important feature of the chemistry of these species. This linkage would of course account for the close association between Tc and Sn observed in many 99mTc-radiopharmaceuticals (11)(12)(13)(14).…”

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“…We have recently reviewed the synthesis of 99mTc-radiopharmaceuticals by the reduction of pertechnetate (11) and it is clear that the chemistry of reduced technetium radiopharmaceuticals is only poorly understood. Several recent papers have indicated that the tin used to reduce pertechnetate not only can function as an electron donor but also may often be intimately associated with the product 99mTc-radiopharmaceutical.…”

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confidence: 99%

“…In order to understand the action of existing 99mTc-radiopharmaceuticals, as well as to plan the synthesis of new 99mTc imaging agents logically, it is necessary to have a more detailed knowledge of the inorganic chemistry of technetium than is now available (11). In this context it would be especially useful to know the oxidation state and coordination geometry of technetium in reduced radiopharmaceuticals, and also to have some idea as to the origins and nature of the Tc-Sn interaction that seems to prevail in the chemistry of these compounds.…”

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Structural characterization of a bridged 99Tc-Sn-dimethylglyoxime complex: implications for the chemistry of 99mTc-radiopharmaceuticals prepared by the Sn (II) reduction of pertechnetate.

Deutsch¹,

Elder²,

Lange³

et al. 1976

Proc. Natl. Acad. Sci. U.S.A.

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Reduction of pertechnetate by tin(I) in the presence of dimethylglyoxime is shown, by single crystal x-ray analysis, to yield a technetium-tin-dimethylglyoxime complex in which tin and technetium are intimately connected by a triple bridging arrangement. One bridge consists of a single oxygen atom and it is hypothesized that this bridge arises from the inner sphere reduction of technetium by tin(II), the electrons being transferred through a technetium "yl" oxygen which eventually becomes the bridging atom. Two additional bridges arise from two dimethylglyoxime ligands that function as bidentate nitrogen donors towards Tc and monodentate oxygen donors towards Sn. The tin atom can thus be viewed as providing a three-pronged "cap" on one end of the Tc-dimethylglyoxime complex. The additional coordination sites around Tc are occupied by the two nitrogens of a third dimethylglyoxime ligand, making the Tc seven-coordinate. The additional coordination sites around Sn are occupied by three chloride anions, giving the Sn a fac octahedral coordination environment. From indirect evidence the oxidation states of tin and technetium are tentatively assigned to be IV and V, respectively. Since most 99mTc-radiopharmaceuticals are synthesized by the tin(I) reduction of pertechnetate, it is likely that the Sn-O-Tc linkage described in this work is an important feature of the chemistry of these species. This linkage also provides a ready rationale for the close association of tin and technetium observed in many 99mTc-radiopharmaceuticals. The practice of diagnostic nuclear medicine involves the use of noninvasive procedures in order to image various organs of the body (1-3). These procedures are based on the tendency of the body to concentrate some chemical form of a particular gamma-ray-emitting isotope in the organ of interest; subsequent scanning of the organ with a gamma-ray camera provides an image from which diagnostic information can be obtained (4-8). It is clear that the radioisotope with optimum nuclear properties for clinical gamma-ray scanning is 99mTc (1, 9, 10) and many imaging procedures based on this isotope are currently in use (3).All 99mTc-radiopharmaceuticals, except pertechnetate itself, are prepared via the reduction of 99mTc04- (pertechnetate) in the presence of a potential ligand, the reductant most commonly employed being an aqueous HCl solution of stannous chloride. We have recently reviewed the synthesis of 99mTc-radiopharmaceuticals by the reduction of pertechnetate (11) and it is clear that the chemistry of reduced technetium radiopharmaceuticals is only poorly understood. Several recent papers have indicated that the tin used to reduce pertechnetate not only can function as an electron donor but also may often be intimately associated with the product 99mTc-radiopharmaceutical. In three specific cases, i.e., 99mTc(Sn)-tetracycline (12), 99MTc(Sn)-ethane-l-hydroxy-1,1-diphosphonate (13), and 99mTc(Sn)-polyphosphate (14), double labeling with radioactive tin and technetium has established tha...

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