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Technetium binuclear complexes

In compliance with the nuclearity principle, polynuclear clusters are subdivided into a number of other subgroups, e.g. hexanuclear, octanuclear, etc. The binuclear clusters of technetium may be classified according to the electronic structure of their Tc-Tc2 bonds. Then, the d4-d4 complexes with quadruple M-M bonds are the father of all binuclear complexes with Tc-Tc bonds. The addition or removal of electrons from Tc-Tc bonds [1,11] should result in a decrease in the formal multiplicity of M-M bonds. Thus, for instance, the formal multiplicity of Tc-Tc bonds of d3-d3 and d5-d5 binuclear complexes equals3 3, that of d4 d5 and d4-d3 complexes equals 3.5, etc. [Pg.193]

The paper electrophoresis experiments carried out to study the mobility of polynuclear technetium clusters in aqueous solutions of HX of varying acidity, as a mobile phase, showed that these clusters were also characterized by reversible reactions such as (5) without leading to destruction of M-M bonds. On the other hand, an autoclave recrystallization of the polynuclear clusters at 200-220°C in an atmosphere of argon from concentrated solutions of HX led to a partial destruction of M-M bonds and the formation of binuclear complexes [Tc2X8]3 and [Tc,X6]2. This indirectly shows that reactions (6) and (7), leading to the destruction of M-M bonds, are likely in solutions of polynuclear clusters [15]. [Pg.219]

Literature data are available on the electronic structures of two more binuclear technetium complexes [(NHjLlOHLTcf/i-O TcfOH NHj ] (a hypothetical complex with the structure and composition analogous to those of the ethylen-diamminetetra-acetate complex [54,55]) and Tc2(CO)10 (a binuclear complex with strong crystal field ligands [168,169]. We shall consider the results of these calculations in greater detail. [Pg.241]

In section 5.2.3 it is shown that in contrast to binuclear complexes of other elements [1,10,11] for technetium compound this statement is not true. [Pg.192]

Among other widely used reducers for the synthesis of binuclear technetium complexes with M-M bonds, zinc in HC1 and H3P02 [1,11] are most important. These reducers, as a rule, are used for the synthesis of Re clusters of similar structure. [Pg.194]

Tc2[(CH3)3CCOO]4 C12. The first binuclear d4-d4 technetium complex was obtained by Cotton and Gage [45] by oxidative substitution of the chloride ions in the coordination sphere of [Tc2Cl8]3 by trimethylacetate ions. The substitu-... [Pg.201]

Fig. 4. Schematic presentation of nearest ligand surrounding the binuclear d3-d3 and d3-d2 technetium complexes (according to [11])... Fig. 4. Schematic presentation of nearest ligand surrounding the binuclear d3-d3 and d3-d2 technetium complexes (according to [11])...
Electronic Structure of Binuclear Technetium Complexes 5.2.1 Octachloroditechnetates... [Pg.235]

Calculations of the electronic structure of the complexes of this type were first carried out for [Tc2C18]3, using the semi-empirical EHT method [146], It was shown that a strong quadruple M-M bond is formed in both the d4-d4 binuclear transition-metal complexes and d4-d5 technetium complexes. The addition of an excess electron does not decrease the Tc-Tc bond strength,... [Pg.235]

Whatever the advantages of the SCF calculations with the Cl s, they do not always give good results, as is the case for M2 molecules with quintuple and sextuple M-M bonds [135,156], Nevertheless, some deviations from the simple MO scheme can be explained using simpler qualitative arguments. For example, the increased ability of technetium to form d4-d5 complexes and their greater stability in comparison to that of the d4-d4 complexes are explained on the basis of a model of the electrostatic repulsion of M atoms with like charges in a binuclear cluster [10,90,150] or on the basis of different diffusivities of cr, o, n, 5 and S metallic MO s of the clusters [63,141,157]. [Pg.237]

Thus, the investigations performed [58,77] showed that [Tc2(/t-CH3COO)4] [TCO4J2 combines the properties of two classes of technetium complexes those of pertechnetates and those of binuclear carboxylates with multiple M-M bonds. On the other hand, the anionic and cationic fragments of this compound are characterized by a mutual effect which affects their electronic and molecular structures. [Pg.240]


See other pages where Technetium binuclear complexes is mentioned: [Pg.193]    [Pg.193]    [Pg.200]    [Pg.205]    [Pg.231]    [Pg.240]    [Pg.355]    [Pg.361]    [Pg.223]    [Pg.435]    [Pg.440]    [Pg.435]    [Pg.440]    [Pg.471]    [Pg.476]    [Pg.146]    [Pg.192]    [Pg.192]    [Pg.199]    [Pg.204]    [Pg.230]    [Pg.239]    [Pg.4317]    [Pg.4322]    [Pg.94]    [Pg.95]    [Pg.191]    [Pg.191]    [Pg.201]    [Pg.202]    [Pg.207]    [Pg.209]    [Pg.210]    [Pg.225]    [Pg.236]   
See also in sourсe #XX -- [ Pg.41 , Pg.48 , Pg.49 , Pg.50 ]

See also in sourсe #XX -- [ Pg.48 , Pg.49 , Pg.50 ]

See also in sourсe #XX -- [ Pg.48 , Pg.49 , Pg.50 ]




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