Technetium related complexes

Turning now to H2 complexes, several compounds that are likely to be H2 complexes have been reported. For technetium it would seem to be nearly certain that TcCl(dppe)2(H2) is an example,57 although neutron diffraction evidence is still lacking. However, it appears that there may be a related complex, TcH3(dppe)2, containing three H" ligands, but obtained by a different synthetic route.58... 

Dinitrogen, Phosphine, Phosphite, and Related Complexes Complexes with Nitrogen Ligands Nitrosyl and Thionitrosyl Complexes Technetium(II)... 

Thirdly, some obvious applications of coordination chemistry are omitted from this volume if they are better treated elsewhere. This is the case when a specific application is heavily associated with one particular element or group of elements, to the extent that the application is more appropriately discussed in the section on that element. Essentially all of the coordination chemistry of technetium, for example, relates to its use in radioimmunoimaging inclusion of this in Chapter 20 of this volume would have left the chapter on technetium in Volume 5 almost empty. For the same reason, the applications of actinide coordination complexes to purification, recovery,... 

Fig. 21. Comparison of half-lives. [Data from Table VII (equatorial ligand substitution, Table VIII (aqua substitution and related reactions) and Table IX (in vivo reactions of technetium and rhenium radiopharmaceuticals) of the complexes described in Section VII,A. Similar symbols denote similar technetium and rhenium complexes.]...

The silane o-complexes 11 have been intensively studied as discussed above and in Refs. 2, 4, and 12-14. No examples of such complexes are known for technetium, whereas the related rhenium complex [Re(H)(SiR3)(CO)2Cp] has been concluded to be classical on the grounds of a long-estimated Si-H distance of 2.2 A. Schubert favors a classical description of the latter compound, whereas Kubas noted that this distance may correspond to a stretched a-complex on the verge of oxidative... 

By far, the largest number of structurally characterized rhenium complexes contain the metal in the oxidation state +5 . This can be attributed to the high stability of the rhenium(V) oxo, nitrido, and imido cores with a great variety of ligand systems, but is doubtlessly also related to the fact that rhenium complexes are frequently used as nonradioactive model compounds for the development of technetium radiopharmaceuticals. The dominance of 0 , and NR ligands can be... 

Complexes of technetium in oxidation states ranging from (-1) to (VII) have been prepared chemically and characterized. However, historically only the higher oxidation states (IV), (V) and (VII) have been of major importance in radiopharmaceutical formulations. More recently there has been increased interest in lower oxidation state technetium complexes for medical applications, and the use of ir-acceptor ligands has allowed the preparation of Tc1 complexes which are stable in vivo. The coordination chemistry of technetium has been described in Chapter 42 and recent reviews have been provided by Davison21 and by Schwochau.22 Reviews which relate to medical applications of technetium are given by Jones and Davison,549 Deutsch et al.,20 Deutsch and Barnett,550 Siedel551 and Clarke and Fackler.552 The in vivo chemistry of "mTc chelates has been described by Eckelman and Volkert,553 while the structures of technetium complexes, determined by X-ray diffraction techniques, have been reviewed by Bandoli et ai554... 

Little related work on the technetium analog has been completed. Much of the synthetic work with high-valent Tc has centered on imido complexes,54 or on complexes for use in radiopharmaceuticals.55 Methyl technetium trioxide has been prepared.8 This species is thermodynamically a powerful enough oxidant to cycloadd to alkenes cyclohexene gave (after hydrolysis) c/s-l,2-cyclohexanediol. No chemistry with H202 has been reported it is expected to behave in a similar manner to MTO, unless the change in the metal-oxo bond strength perturbs the overall thermodynamics. 

The importance of technetium-99m radiopharmaceuticals stimulated numerous studies related to the basic chemistry of long-lived technetium Tc. A great number of technetium complexes reviewed in the preceding sections has been synthesized and characterized. Exact technetium analyses in these compounds have been needed to confirm their composition. Besides the traditional determinations of Tc by conductometric titrations of pertechnetate or by liquid scintillation counting, neutron activation of Tc has also been... 

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