Chemistry at High Dilution: Dinuclear 99 m Tc Complexes

The formation of di- or polynuclear complexes at nanomolar concentrations is generally too slow to be observed with 99mTc. It is reported in this communication that an appropriate choice of potentially bridging ligands, herein thiols HS-R, accelerates the dimerization reaction to an extent that dinuclear complexes are formed at very high dilution. The dinuclear nature of [99mTc2(m2-SR)3(CO)6]- is shown by chromatographic comparison, not only with its rhenium homologue as commonly done, but also with the true 99Tc analogue.