Synthesis and characterization of complexes of the {ReO}³⁺ core with SNS and S donor ligands

The reaction of [ReOCl₃(PPh₃)₂] with N,N-bis(2-mercaptoethyl)benzylamine and 4-bromobenzenethiol allowed for the isolation of [ReO{η³-(SCH₂CH₂)₂N(CH₂C₆H₅)}-(η¹ I-C₆H₄Br-4-S)] (1). The reaction of [ReOCL₃(PPh₃)₂] with [(HSCH₂CH₂)₂N(CH₂C₅H₄N)] and the appropriate thiol in chloroform treated with triethylamine has led to the isolation of a series of neutral rhenium complexes of the type [ReO{η³-(SCH₂CH₂)₂N(CH₂C₅H₄N)}(η¹-C₆H₄X-4-S)] (X=Br (2), Cl (3), F (4), and OCH₃ (5)) and [ReO{η³-(SCH₂CH₂)₂N(CH₂C₅H₄N)}(η¹-C₆H₄OCH₃-4-CH₂S)] (6). Likewise, under similar reaction conditions, the use of the related tridentate ligand, [(HSCH₂CH₂)₂N(CH₂CH₂C₅H₄N)], has led to the isolation of a series of rhenium complexes of the type [ReO{η³-(SCH₂CH₂)₂N(CH₂CH₂C₅H₄N)}(η<¹-C₆H₄X-4-S)] (X=Br (7), Cl (8), OCH₃ (9)), as well as [ReO{η³-(SCH₂CH₂)₂N(CH₂CH₂C₅H₄N)}(η¹-C₆H₄C1-4-CH₂S)]·0.5CH₃ (CH₂)₄CH₃ (10). These compounds are extensions of the '3 + 1' approach to the synthesis of materials with the {MO}³⁺ core (M = Tc and Re), which have applications in nuclear medicine. The ligands chosen allow systematic exploration of the consequences of para-substitution on the monodentate thiolate ligand [S] and of derivatization of the substituent R on the tridentate aminodithiol ligand [SNS] of the type (HSCH₂CH₂)₂NR. Such modifications can influence lipophilicity, charge, size and molecular weight of the complex and consequently the biodistribution. (C) 2000 Elsevier Science S.A.