Thiols, with pertechnetate

In addition, several Tc(V) complexes based on the 0=Tc(S)4-core have been prepared. The preparation w as achieved by exchange reaction of Tc(V) gluconate with various dithiols in aqueous cthanolic solution. The oxo-dithiolatotechnetatc(V) complexes were mostly precipitated as the Et4N] salts. The complex compounds turned out to be diamagnetic in solution, and have probably square pyramidal structure [117,118,119]. Stereoisomcric complexes derived from mesa and racemic 2.3-dimer-captosuccinic acid dimethylcster were identified by H NMR [120]. The kinetics of the reaction between pcrtcchnetatc and meso- or racemic dimcrcaptosuccinic acid in hydrochloric acid solution were studied. The reaction was found to be first order in each reactant [121]. Also the reaction of pertechnetate with para-substituted benzene thiols was followed and showed a simple second order kinetics. The reaction rate decreased when the substituent became more electron-withdrawing [122]. 

Like their amine analogues (Section 20.4.2.1) thiol-substituted alcohols may act as bidentates with chelation often leading to polymeric products. The stability constants of the Cd" complexes of both 2-mercaptoethanol (mel) and 3-mercapto-1,2-propanediol (mpd) have been determined, with polymeric structures being concluded similar to those of the previously determined Ni and Zn compounds. Similar data for the Pb" complexes showed polymer formation with mpd and gave evidence for Pb-mel species with at least five different metal ligand ratios. Reaction of the pertechnetate(VII) ion [Tc04] with sodium dithionite and 2-mercaptoethanol results in the... 

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