Tricarbonyltechnetium(I) and -rhenium(I) complexes with N′-thiocarbamoylpicolylbenzamidines

N,N-Dialkylamino(thiocarbonyl)-N′-picolylbenzamidines react with (NEt4)2[M(CO)3X3] (M = Re, X = Br; M = Tc, X = Cl) under formation of neutral [M(CO)3L] complexes in high yields. The monoanionic NNS ligands bind in a facial coordination mode and can readily be modified at the (CS)NR1R2 moiety. The complexes [99Tc(CO)3(LPyMor)] and [Re(CO)3(L)] (L = LPyMor, LPyEt) were characterized by X-ray diffraction. Reactions of [99mTc(CO)3(H2O)3]+ with the N′-thiocarbamoylpicolylbenzamidines give the corresponding 99mTc complexes. The ester group in HLPyCOOEt allows linkage between biomolecules and the metal core.

Graphical abstractN,N-Dialkylamino(thiocarbonyl)-N′-picolylbenzamidine ligands bind to the [M(CO)3]+ core (M = Re, 99Tc, 99mTc) in a facial coordination mode to give neutral [M(CO)3(L)] complexes in high yields. The ligands are modified at the (CS)-NR1R2 moiety. The ester group in HLPyCOOEt allows linkage between biomolecules and the metal core.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Tridentate ligands with S,N,N donor sets form stable [M(CO)3(L)] (M = Re, 99Tc) complexes. ► The ligands can be modified in their periphery with an ester group. ► Complexes with the modified ligands are candidates for bioconjugation. ► 99mTc complexes of the ligands can be prepared from [99mTc(CO)3(H2O)3]+.