Bis-arene sandwich complexes are generally prepared by the Fischer-Hafner reaction, which conditions are incompatible with most O-and N-functional groups. We report a new way for the synthesis of sandwich type complexes [Re(η 6 -arene) 2 ] + and [Re(η 6 -arene)(η 6 -benzene)] + from [Re(η 6 -napht) 2 ] + and [Re(η 6 -napht)(η 6 -benzene)] + , with functionalized arenes and pharmaceuticals. N-methylpyrrolidine (NMP) facilitates the substitution of naphthalene with the incoming arene. A series of fully characterized rhenium sandwich complexes with simple arenes, such as aniline, as well as with active compounds like lidocaine and melatonin are presented. With these rhenium compounds in hand, the radioactive sandwich complexes [ 99m Tc(η 6 -pharm) 2 ] + (pharm = pharmaceutical) can be unambiguously confirmed. The direct labelling of pharmaceuticals with 99m Tc through η 6coordination to phenyl rings and the confirmation of the structures with the rhenium homologues opens a path into molecular theranostics.

The labeling of (bio)molecules with metallic radionuclides such as 99mTc demands conjugated, multidentate chelators. However, this is not always necessary since phenyl rings can directly serve as integrated, organometallic ligands. Bis‐arene sandwich complexes are generally prepared by the Fischer–Hafner reaction. In extension of this, we show that [99mTc(η6‐C6R6)2]+‐type complexes are directly accessible from water and [99mTcO4]−, even using arenes incompatible with Fischer–Hafner conditions. To unambiguously confirm the nature of these unprecedented 99mTc complexes, their rhenium homologous have been prepared by substituting naphthalene ligands in [Re(η6‐C10H8)2]+ with the corresponding phenyl groups. The ease with which highly stable [99mTc(η6‐C6R6)2]+ complexes are formed under standard labeling conditions enables a multitude of new potential imaging agents based on commercial pharmaceuticals or lead structures.

Due to its long half-life of 2.111×105 y, technetium, i.e. 99Tc, offers the excellent opportunity of combining fundamental and ' classical ' organometallic or coordination chemistry with all methodologies of radiochemistry. Technetium chemistry is inspired by the applications of its short-lived metastable isomer 99mTc in molecular imaging and radiopharmacy. We present in this article examples about these contexts and the impact of purely basic oriented research on practical applications. This review shows how the chemistry of this element in the middle of the periodic system inspires the chemistry of neighboring elements such as rhenium. Reasons are given for the frequent observation that the chemistries of 99Tc and 99mTc are often not identical, i.e. compounds accessible for 99mTc, under certain conditions, are not accessible for 99Tc. The article emphasizes the importance of macroscopic technetium chemistry not only for research but also for advanced education in the general fields of radiochemistry.

^{The chemistry of rhenium complexes covers oxidation state +VII to -I. Some oxidation states such as +II are only rarely found in literature. One of the reasons is the lack of a suitable stable precursor for the oxidation state +II. However, we have developed a two step synthesis to the fully solvated Re(+II) complex [Re(NCCH}₃⁾₆^]2+^{from [ReO}₄^]-^{via the rhenium bis-arene complex [Re(C}₁₀^H₈⁾₂^]+^{. This fully solvated Re(+II) was fully characterized by various spectroscopic manners, cyclic voltammetry, and X-Ray diffraction analysis. Its potential as a precursor for Re(+II) chemistry was explored with various substitutions reactions with phosphines and halides, and the obtained products were as well fully characterized.<br>}

The labeling of (bio)molecules with metallic radionuclides such as 99mTc demands conjugated, multidentate chelators. However, this is not always necessary since phenyl rings can directly serve as integrated, organometallic ligands. Bis‐arene sandwich complexes are generally prepared by the Fischer–Hafner reaction. In extension of this, we show that [99mTc(η6‐C6R6)2]+‐type complexes are directly accessible from water and [99mTcO4]−, even using arenes incompatible with Fischer–Hafner conditions. To unambiguously confirm the nature of these unprecedented 99mTc complexes, their rhenium homologous have been prepared by substituting naphthalene ligands in [Re(η6‐C10H8)2]+ with the corresponding phenyl groups. The ease with which highly stable [99mTc(η6‐C6R6)2]+ complexes are formed under standard labeling conditions enables a multitude of new potential imaging agents based on commercial pharmaceuticals or lead structures.