Technetium-99m N,N'-Bis(2-mercapto-2-methylpropyl)-2-aminobenzylamine: Technetium-99m Complexes of a Novel Bis(aminoethanethiol) Ligand

Article abstract of DOI:10.1021/jm00046a012

A new N2S2 ligand system, N,N'-bis(2-mercapto-2-methylpropyl)-2-aminobenzylamine, U-BAT, 1, containing uneven amine groups (two amine groups with different pK_a values) for complexing VO>³⁺, was prepared.The reaction of this novel ligand with <99mTc>pertechnetate, in the presence of stannous tartrate as the reducting agent, produces the neutral and lipid-soluble <99mTc>Tc^VO(U-BAT), TcS2C15H23N2O, 2.However, when the same reaction was carried out at a higher pH, 9-10, and with 30 min of heating (100 deg C), a second neutral but more lipid-soluble complex, <99mTc>Tc^VO(OU-BAT), TcS2C15H21N2O, 3, was isolated.The X-ray crystallography data of the 99Tc complexes show square pyramidal coordination with N2S2 as the base and the Tc=O in the apical position.Compound 3 can be derived from 2 by an oxidation of the ligand to form an imine.After iv injection into rats, the neutral and lipid-soluble technetium-99m complexes showed significant brain uptake, 1.54 and 1.07percent dose/organ at 2 min for <99mTc>Tc^VO(U-BAT) and Tc^VO(OU-BAT), respectively.The novel Tc chemistry of this new ligand system may provide a useful foundation for designing Tc complexes with a built-in redox mechanism.