Non-carrier-added and carrier-added experiments using short-lived 99mTc and long-lived 99gTc have been utilized to prepare a series of bis-substituted [Tc(N)(DTC)2] complexes [DTC=dithiocarbamate(1鈭?]. They have been purified by means of chromatographic techniques (high-performance liquid chromatography and thin-layer chromatography) and identified via double detection (UV-vis and radiometry) by comparison with authenticated samples of 99gTc compounds prepared by conventional coordination chemistry procedures.
The molecular structure of the lipophilic, neutral complex cis-[Tc(N)(NOEt)2] has been assigned by comparison with similar nitrido-Tc(V) complexes already reported in the literature. Novel bis-substituted nitrido-Tc complexes containing hydrolyzed portions of coordinated NOEt, namely, N-ethyldithiocarbamate [NHEt(1鈭?] and N-hydroxy, N-ethyldithiocarbamate [NOHEt(1鈭?], have been prepared and characterized by means of multinuclear nuclear magnetic resonance spectroscopy and mass spectrometry.
Despite the identification of these 鈥渉ydrolyzed鈥?species, it is still unclear whether the failure to reach the clinical goal of the perfusion tracer [99mTc(N)(NOEt)2] is related to the degradation processes evidenced in this study or is the result of the mediocre imaging properties of the tracer.