Diketonato-and carboxylato complexes

The first-order exchange reaction was followed by the labeling method using [Tc(acac(2- C])3] . The exchange rale R is expressed by 

In addition to tris(penlanc-2,4-dionato)leehnetium(lII). the analogous complexes with hexane-2,4-dionc, hcptane-2,4-dionc, heptane-3,5-dione, and oetane-3,5-dione were synthesized after reduction of TcO with dithionite, identified by FAB mass spectrometry, and characterized by VIS/IJV and IR spectrophotometry. The hexane- 

4-dionato complex crystallizes in the monoclinic space group / 2//c, isostructurally with tris(pcntanc-2.4-dionato)technctium(IIT) [422J. 

Tris(dipivaloylmethanato)technetium(IIl) (dipivaloyl methane = 2,2.6,6-tetra-methyl-3,5-heptancdione) was obtained by refluxing a mixture of dipivaloylmcthane. (NH4)7 TcClft], sodium methoxide and zinc powder in methanol. The red solid is readily oxidized at A /2 = + 0.12 V vx SCE to the cationic Tc(lV) complex. Tris(trifluoro-acetylacctonato)technctium(III) (trifluoroacctylacetone CF3-CO-CH2-CO-CH3) and tris(hexafluoroacetylacetonato)technetium(III) (hexafluoroacetylacetonc CF3-CO-CH2-CO-CF3) were prepared by reaction of the ligands with NH4TCO4 in refluxing ethanol and reduction with dithionite. These complexes are much more difficult to oxidize [423]. 

The mixed-ligand cationic complex Tc(ITI)-N,N -ethylene-bis-(acetylacetoncthio-iminato)-bis-(triphcnylphosphine) [Te(.sacac)2en(PPh3)2]Cl was prepared by reaction of [Tc 0(H20)(sacac)2en]Cl with PPh3 in methanol  

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