Complexos de CoIII derivados da 2-acetilpiridina N(4)-R tiossemicarbazona (Hatc-R, R = alquil ou aril) foram caracterizados por análise elementar, espectroscopia na região do infravermelho, UV-Visível e ¹H RMN, voltametria cíclica (VC), medidas de condutividade e difração de raios X em monocristal. Os resultados obtidos são consistentes com a oxidação do centro de CoII para CoIII após a coordenação N,N,S-tridentada e monoaniônica dos ligantes tiossemicarbazonas, resultando em complexos octaédricos iônicos do tipo [Co(atc-R)2]Cl. Os estudos de eletroquímica mostram dois processos reversíveis, referentes aos pares redox CoIII/CoII e CoII/CoI, que são afetados pelo efeito indutivo dos grupos substituintes na posição N4 dos ligantes. Dois complexos de CoIII se mostraram satisfatoriamente ativos, com valores de concentração inibitória mínima abaixo de 10 µmol L- 1 e um deles apresentou muito baixa citotoxicidade contra células VERO e J774A.1 (IC50), conferindo-lhe altos índices de seletividade (SI > 10).

CoIII complexes derived from 2-acetylpyridine N(4)-R thiosemicarbazone (Hatc-R, R = alkyl, aryl) have been characterized by elemental analysis, FTIR, UV-Visible and ¹H NMR spectroscopies, cyclic voltammetry (CV), conductimetry measurements and single crystal X-ray diffractometry. The results obtained are consistent with the oxidation of the CoII center to CoIII upon coordination of the monoanionic N,N,S-tridentate thiosemicarbazone ligands, resulting in octahedral ionic complexes of the type [Co(atc-R)2]Cl. Electrochemistry studies show two reversible processes referring to the redox couples CoIII/CoII and CoII/CoI which can be modified by the inductive effects of the substituents groups at the N4 position of the ligands. Two CoIII complexes showed satisfactory activity with minimal inhibitory concentration value under 10 µmol L- 1 and one presented quite low cytotoxicity against VERO and J774A.1 cells (IC50), resulting in high selectivity index (SI > 10).

The antitumorigenic potential of two palladium(II) complexes, [Pd(ca2-o-phen)Cl2 ] - C1 and [Pd(dmba)(dppp)Cl] - C2, was evaluated, using MDA-MB-435 cells, a human breast adenocarcinoma cell-line that does not express the estrogen receptor α (ER-). Growth inhibition and induced alterations in cell-morphology were analyzed. The sulforhodamine B test showed that, compared to control cells, both C1 and C2 significantly inhibited (p < 0.5) cell growth. The maximum effect with both was achieved with 1 µM complexes, after 24 h of treatment. No further cell-growth inhibition was achieved by increasing concentration or incubation time. Cell morphology was analyzed after staining with hematoxylin-eosin (HE). The morphological changes noted in the treated cells were cell rounding-up, shrinkage, nuclear condensation and reduction of cell length (p < 0.05), thereby indicating that both C1 and C2 are cytotoxic to breast adenocarcinoma cells. All together, there was every indication that, by decreasing cell growth and inducing morphological changes, the tested complexes are cytotoxic, hence their potentiality as promising candidates for antineoplastic drug development.

The present paper deals with the bis-insertion reactions of 1,2-diphenylacetylene into Pd-C bond of the cyclopalladated complexes [Pd(dmba)(µ-NCO)]2 (1) and [Pd(dmba)(MeCN)2](NO3) (2) (dmba = N,N-dimethylbenzylamine, MeCN = acetonitrile). Two new complexes [Pd{PhC=CPh-CPh=CPhC6H4CH2N(CH 3)2}(NCO)] (3) and [Pd{PhC=CPh-CPh=CPhC6H4CH2N(CH 3)2}(NO3 )] (4) were obtained and characterized by IR and NMR spectroscopy and elemental analysis.

No presente trabalho é descrita a investigação do comportamento térmico de uma nova série de complexos ciclopaladados, obtidos a partir de reações do azido-complexo [Pd(dmba)(mi-N3)]2 (1) (dmba = N,N-dimetilbenzilamina) com os azo-ligantes aniônicos pirazolato (pz), imidazolato (imz) e 3,5-dimetil-pirazolato (3,5-dmpz). Os compostos binucleares [Pd(dmba)(mi-pz)]2 (2), [Pd(dmba)(mi-imz)]2 (3) e [Pd(dmba)(mi-3,5-dmpz)]2 (4) foram caracterizados por análise elementar, espectroscopia de absorção na região do infravermelho, espectroscopia de RMN de 13C{¹H} e ¹H e análise termogravimétrica. O produto final de decomposição térmica, paládio metálico, foi caracterizado pela difratometria de raios-X, método do pó.

The present paper deals with the thermal behavior study of cyclopalladated complexes obtained from reactions of [Pd(dmba)N3]2 (1), dmba = N,N-dimethylbenzylamine, with azole-compunds, such as, the anionic ligands pyrazolate (pz), imidazolate(imz) and 3,5-dimethyl-pyrazolate (3,5-dmpz). The characterization of the binuclear complexes [Pd(dmba)(mu-pz)]2 (2), [Pd(dmba)(mu-imz)]2 (3) and [Pd(dmba)(mu-3,5-dmpz)]2 (4) was carried out by elemental analysis, IR and NMR spectroscopy. Their thermal behaviour has been investigated and the final product was identified by X-ray powder diffractometry which showed the formation of Pd(0) as final decomposition product.

Investigou-se o comportamento eletroquímico dos dímeros ciclopaladados [Pd(dmba)(mi-X)]2 [X = Cl (1), NCO (2), NCS (3), CN (4)] (dmba = N,N-dimetilbenzilamina) e do monômero [Pd(dmba)(MeCN)2][NO3] (MeCN = acetonitrila). Os resultados experimentais mostraram redução de Pd(II) para Pd(I) para os compostos 1-3, enquanto que somente para 1 observou-se a redução de Pd(I) para Pd(0) em uma única etapa. O complexo 5 mostrou redução de Pd(II) para Pd(0). Observou-se que a estabilidade eletroquímica destes compostos diminuem na seguinte ordem: [Pd(dmba)(mi-CN)]2 (4) > [Pd(dmba)(mi-NCO)]2 (2) > [Pd(dmba)(mi-SCN)]2 (3) > [Pd(dmba)(MeCN)2][NO3] (5) > [Pd(dmba)(mi-Cl)]2 (1).

The electrochemistry behaviour of compounds [Pd(dmba)(mu-X)]2 [X = Cl (1), NCO (2), NCS (3), CN (4)] and [Pd(dmba)(MeCN)2][NO3] (5) (dmba = N,N-dimethylbenzylamine, MeCN = acetonitrile) are reported. The experimental results showed the reduction of Pd (II) to Pd (I) for complexes 1- 3 while 1 was the only one to show the reduction of Pd (I) to Pd (0). It was observed that the electrochemical stability of these compounds decreased in the order: [Pd(dmba)(mu-CN)]2 (4) > [Pd(dmba)(mu-NCO)]2 (2) > [Pd(dmba)(mu-SCN)]2 (3) > [Pd(dmba)(MeCN)2][NO3] (5) > [Pd(dmba)(mu-Cl)]2 (1).