title: Rhenium mixed-ligand complexes with S,N,S-tridentate thiosemicarbazone/thiosemicarbazide ligands.
abstract: Rhenium(V) complexes containing tridentate thiosemicarbazones/thiosemicarbazides (H2L1) derived from N-[N′,N′-dialkylamino(thiocarbonyl)]benzimidoyl chlorides with 4,4-dialkylthiosemicarbazides have been synthesized by ligand-exchange reactions starting from [ReOCl(L1)]. The chlorido ligand of [ReOCl(L1)] (4) is readily replaced and reactions with ammonium thiocyanate or potassium cyanide give [ReO(NCS)(L1)] (6) and [ReO(CN)(L1)] (7), respectively. The reaction of (NBu4)[ReOCl4] with H2L1 and two equivalents of ammonium thiocyanate, however, gives in a one-pot reaction [ReO(NCS)2(HL1)] (8), in which the pro-ligand H2L1 is only singly deprotonated. An oxo-bridged, dimeric nitridorhenium(V) compound of the composition [{ReN(HL1)}2O] (11) is obtained from a reaction of (NBu4)[ReOCl4], H2L1 and sodium azide. The six-coordinate complexes [ReO(L1)(Ph2btu)] (12), where HPh2btu is N,N-diphenyl-N′-benzoylthiourea, can be obtained by treatment of [ReOCl(L1)] with HPh2btu in the presence of NEt3. Studies of the antiproliferative effects of the [ReOX(L1)] system (X = Cl−, NCS− or CN−) on breast cancer cells show that the lability of a monodentate ligand seems to play a key role in the cytotoxic activity of the metal complexes, while the substitution of this ligand by the chelating ligand Ph2btu− completely terminates the cytotoxicity.
authors: Instituto de Química de São Carlos, Universidade de São Paulo, CP 780, São Carlos-SP, Brazil.
authors: Pedro I da S
authors: PI
authors: Maia
authors: Hung Huy
authors: HH
authors: Nguyen
authors: Adelheid
authors: A
authors: Hagenbach
authors: Silke
authors: S
authors: Bergemann
authors: Ronald
authors: R
authors: Gust
authors: Victor M
authors: VM
authors: Deflon
authors: Ulrich
authors: U
authors: Abram
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry* / Q000633:toxicity; D018360:Crystallography, X-Ray; D006801:Humans; D008024:Ligands; D061986:MCF-7 Cells; D008968:Molecular Conformation; D012211:Rhenium / Q000737:chemistry*; D012663:Semicarbazides / Q000737:chemistry*; D019810:Sodium Azide / Q000737:chemistry; D013882:Thiosemicarbazones / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D008024:Ligands; D012663:Semicarbazides; D013882:Thiosemicarbazones; C005151:thiosemicarbazide; D012211:Rhenium; D019810:Sodium Azide