This work reports the synthesis, structure and catalytic activity of a novel ruthenium(II) complex, [RuCl(dppb)(44bipy)(4-pic)]PF6 (where dppb = 1,4-bis(diphenylphosphine)butane; 44bipy = 4,4’-dimethyl-2,2’-dipyridyl; 4-pic = 4-picoline). The molecular structure and catalytic activity were studied by Fourier transform infrared (FTIR), UV-Vis and nuclear magnetic resonance (NMR) spectroscopies, cyclic voltammetry, and X-ray crystallography, while the electronic structure was investigated by density-functional theory (DFT) and time dependent DFT (TD-DFT) methods. Electrochemical studies showed the substitution of the chlorido ligand from the precursor by the 4-pic ligand, exhibiting the RuII/RuIII process at 1.21 V. The structure of the compound was optimized using DFT simulations and showed data similar to the X-ray structure. The UV-Vis absorption spectrum showed a good agreement with TD-DFT simulations. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies were determined at the Becke, 3-parameter, Lee-Yang-Parr (B3LYP) level. The study of the catalytic activity in the transfer hydrogenation of ketones by the 1H NMR showed efficient transfer hydrogenation reaction at 60 ºC, employing acetophenone as substrate and resulting in a high conversion. The formation of two ruthenium-hydride species was observed.

Mononuclear and binuclear RuII/arene/triphenylphosphine complexes with p-substituted benzoic acid derivatives were prepared and characterized. These monocationic complexes of type [Ru(η6-p-cymene)(PPh3)L] (L = benzoic acid (1), p-hydroxybenzoic acid (2), p-nitrobenzoic acid (3) and terephthalic acid (4)) were characterized using various techniques, such as nuclear magnetic resonance (NMR) and matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry, and the crystal structure of 1, 3 and 4 were determined by X-ray diffraction analysis. The cytotoxicity of the complexes was evaluated, in vitro, against tumorigenic [MDA-MB-231, MCF-7 (breast), A549 (lung) and DU-145 (prostate)] and non-tumorigenic [MCF-10A (breast), MRC-5 (lung) and PNT-2 (prostate)] cells. The binuclear complex (4) was inactive due to its low solubility. Complexes 1, 2 and 3 showed similar cytotoxicity, however, complex 1 presented better selectivity index against MDA-MB-231 than compounds 2 and 3. Cellular ruthenium absorption was explored by inductively coupled plasma mass spectrometry (ICP-MS) analyzing the whole cells and the culture medium. Complementary studies showed that complex 1 inhibited colony formation, induced morphology changes in cells and promoted cell cycle arrest in the Sub-G1 phase for the MDA-MB-231 cells.

Herein we present four new ruthenium(II) complexes: [Ru(mtz)2(dppb)] (1), [Ru(mmi)2(dppb)] (2), [Ru(dmp)2(dppb)] (3), and [Ru(mpca)2(dppb)] (4), where mtz = 2-mercaptothiazoline; mmi = 2-mercapto-1-methyl-imidazole; dmp = 4,6-diamino-2-mercaptopyrimidine; mpca = 6-mercaptopyridine-3-carboxylic acid; dppb = 1,4-bis(diphenylphosphino)butane. In vitro cell culture experiments revealed cytotoxic activity for complexes 2, 3 and 4 against MCF-7 (breast, non-invasive), MDA-MB-231 (breast, invasive), A549 (lung), DU-145 (prostate) and HepG2 (liver) tumor cells, in some cases lower than the half maximal inhibitory concentration (IC50) for the reference drug (cisplatin). The deoxyribonucleic acid (DNA) interactions studied by viscosity measurements, gel electrophoresis and square-wave voltammetry indicated that the DNA binding affinity primarily occurs through non-covalent interactions. Only complex 2 was able to fully inhibit the DNA supercoiled relaxation mediated by human topoisomerase IB (Top IB). The analysis indicates that complex 2 inhibits the cleavage and the reconnection steps of the catalytic cycle, being both a poison and a catalytic inhibitor.

The syntheses, characterization, cytotoxicity against tumor cells and anti-Mycobacterium tuberculosis activity assays of PtII/PPh3/N,N-disubstituted-N'-acylthioureas complexes with general formulae [Pt(PPh3)2(L)]PF6, PPh3 = triphenylphosphine; L = N,N-disubstituted-N'-acylthiourea, are here reported. The complexes were characterized by elemental analysis, molar conductivity, infrared (IR), nuclear magnetic resonance (NMR) (1H, 13C{1H} and 31P{1H}) spectroscopy. The 31P{1H} NMR data are consistent with the presence of two PPh3 ligands cis to each other position, and one N,N-disubstituted-N'-acylthiourea coordinated to the metal through O and S, in a chelate form. The structures of the complexes were determined by X-ray crystallography, forming distorted square-planar structures. The complexes were tested in human cell lines carcinomas and also screened with respect to their anti-Mycobacterium tuberculosis activity (H37RvATCC 27294). It was found that complexes with N,N-disubstituted-N'-acylthiourea containing open and small chains as R2 groups show higher cytotoxic and higher anti-Mycobacterium tuberculosis activity than those containing rings in this position.

As reações de substituição [RuCl2(P-P)(N-N)] + L → [RuCl(L)(P-P)(N-N)]+ + Cl-, onde P-P = 1,4-bis(difenilfosfino)butano e N-N = 2,2´-bipiridina, 4,4´-dimetóxi-2,2´-bipiridina, 4,4´-dimetil-2,2´-bipiridina e 4,4´-dicloro-2,2´-bipiridina, L = piridina (py) ou 4-metilpiridina (4-pic), foram estudadas sob condições de pseudo-primeira ordem. As reações ocorrem por um mecanismo dissociativo e as constantes de velocidade nas reações de substituição aumentam com o aumento do pKa dos ligantes N-heterocíclicos e com a diminuição dos potenciais de oxidação do centro metálico. Quanto mais alta é a porcentagem de participação dos orbitais atômicos d do metal na formação do HOMO, conforme calculado pelo método DFT, mais fácil é a dissociação do cloreto da esfera de coordenação do complexo. Nos espectros de 31P{¹H} RMN da série de complexos de fórmula geral [RuCl(L)(P-P)(N-N)]PF6, há dois dubletos com Δσ < 1, o que é consistente com produtos formados pela dissociação do cloreto trans ao átomo de fósforo nos precursores.

The substitution reactions [RuCl2(P-P)(N-N)] + L → [RuCl(L)(P-P)(N-N)]+ + Cl-, where P-P = 1,4-bis(diphenylphosphino)butane and N-N = 2,2´-bipyridine, 4,4´-dimethoxy-2,2´-bipyridine, 4,4´-dimethylpyridine-2,2´-bipyridine and 4,4´-dichloro-2,2´-bipyridine, L = pyridine (py) or 4-methylpyridine (4-pic), were studied under pseudo-first order conditions. The reactions proceeded by means of a dissociative mechanism. The rate constants of the substitution reactions increased as the pKa of the N-heterocyclic ligands increased and as the oxidation potential of the metal center decreased. The greater the participation of the atomic d orbitals of the metal in the HOMO, according to DFT calculations, the easier is the dissociation of the chloride from the coordination sphere of the complex. In the 31P{¹H} NMR spectra of the series of complexes of general formula [RuCl(L)(P-P)(N-N)]PF6, there are two doublets with Δσ < 1. This is consistent with products formed by dissociation of the chloride trans to one of the phosphorus atoms in the precursors.

The [RuCl(bipy)(dppb)(4-pic)]PF6 complex was prepared and fully characterized. The X-ray crystal structure of this complex was determined in order to make an unambiguous distinction between the two possible positions of the 4-methylpyridine ligand (4-pic) in the compound: trans to phosphorus atom or trans to nitrogen atom. The [RuCl(bipy)(dppb)(4-pic)]PF6 complex exhibits an unusual temperature-dependent accidental degeneracy of the 31P chemical shifts in its solution NMR spectrum.

Dois novos complexos zwitteriônicos de oxorrênio(V), [ReOCl2(Hdhp)(PPh3)] (1) e [ReOBr2(Hdhp)(PPh3)] (2) (H2dhp = 2,3-dihidroxipiridina), foram sintetizados e caracterizados por espectroscopia de absorção no infravermelho, ressonância magnética nuclear de ¹H e 31P, análise elementar e determinação da estrutura cristalina e molecular por difração de raios X em monocristais. Os complexos apresentam geometria de coordenação octaédrica bastante distorcida, com os dois ligantes haletos arranjados em posições cis equatoriais, o ligante trifenilfosfina em posição trans a um dos haletos e o ligante Hdhp- coordenado de forma bidentada através de seus átomos de oxigênio, sendo um em posição trans ao ligante oxo e o outro em posição trans com relação ao outro haleto. Este ligante tem seu átomo de nitrogênio protonado. Os compostos 1 e 2 apresentam empacotamento cristalino bastante diferente, influenciado em ambos os casos por ligações de hidrogênio intermoleculares dos tipos N-H<FONT FACE=Symbol>...</FONT>X (X = Cl, Br) e N-H...O.

Two novel zwitterionic oxorhenium(V) complexes, [ReOCl2(Hdhp)(PPh3)] (1) and [ReOBr2(Hdhp)(PPh3)] (2) (H2dhp = 2,3-dihydroxypyridine), were synthesized and characterized by infrared spectroscopy, ¹H and 31P nuclear magnetic resonance, elemental analysis and crystal and molecular structure determination by X-ray diffraction on single crystals. Both complexes show distorted octahedral coordination geometry, with the halide ligands arranged in equatorial cis positions, the triphenylphosphine ligand in a trans position to one of the halides and the Hdhp- ligand coordinated in a bidentate form through its oxygen atoms, one in trans position to the oxo-ligand and the other in trans position to the second halide. The nitrogen atom of this ligand is protonated. Compounds 1 and 2 show quite different crystal packing, both influenced by hydrogen bonds of the types N-H...X (X = Cl, Br) and N-H<FONT FACE=Symbol>...</FONT>O.

Os compostos hidrotris(2-mercaptotiazolil)borato de potássio, KMt, (1), e hidrotris(2-metimazolil)borato de potássio, KTm, (2), foram preparados ao se reagir a amina tiol correspondente com KBH4. Foram caracterizados por métodos espectroscópicos e análise elementar. As estruturas no estado sólido de KMt.4H2O e do composto 2 foram determinadas por análises de difração de raios-X. A maior maciez do ânion em KMt.4H2O, em comparação com 2, é indicada pela ausência de interação entre ele e o cátion, que possui moléculas de água em sua esfera de coordenação. Em KMt.4H2O a geometria em torno do íon potássio é octaédrica distorcida e em 2, pirâmide de base quadrada distorcida. Em 2 o íon potássio está coordenado a dois átomos de enxofre dos anéis de um mesmo ânion e a três outros átomos de enxofre pertencentes a unidades KTm vizinhas. Ambos os compostos possuem uma estrutura polimérica.

Potassium hydrotris(2-mercaptothiazolyl)borate, KMt, (1) and potassium hydrotris(2-methimazole), KTm, (2), were prepared by reacting the appropriate amine thiol with KBH4. They were characterized by spectroscopic methods and elemental analysis. Solid state structures of KMt.4H2O and compound 2 were determined by X-ray diffraction analyses. The softer nature of the anion in the former as compared to 2 is indicated by the lack of interaction of the anion with the cation, that has water molecules in its coordination sphere. In KMt.4H2O the geometry around the potassium cation is distorted octahedral and in 2, distorted square pyramidal. In 2 the potassium ion is coordinated to two sulfur atoms of one hydrotris(methimazole)borate unit and to other three sulfur atoms belonging to neighboring KTm units. Both compounds have a polymeric structure.

Reportamos neste trabalho o estudo sistemático de fragmentação dos derivados de N-óxidos de 1,2,5-oxadiazóis por espectroscopia de massa, usando análogos marcados com deutério para identificar algumas fragmentações críticas. Foi confirmada a perda neutra de CH2O a partir do N2-óxido de 3-hidroximetil-4-fenil-1,2,5-oxidiazol, usando o análogo mono-deuterado. A perda de OH, a partir do oxigênio do N-óxido, por um rearranjo beta-H e delta-H, foi claramente verificada a partir do N2-óxido de 3-(4-metilpiperazina-1-metil)-4-fenil-1,2,5-oxidiazol, usando-se o analogo tetra-deuterado adequado. O isômero N-óxido e análogos desoxigenados foram também usados para confirmar a participação do fragmento óxido no processo de defragmentação.

This paper reported on the study of fragmentation pattern in mass spectrometry of 1,2,5-oxadiazole N-oxide derivatives involving deuterium-labeled analogues to identify some critical fragmentations. A neutral CH2O loss from 3-hydroxymethyl-N2-oxide-4-phenyl-1,2,5-oxadiazole was confirmed with the corresponding mono-deuterated analogue. An OH loss, involving the oxygen of N-oxide, via beta-H and delta-H rearrangement, was clearly revealed from 3-(4-methylpiperazine-1-ylmethyl)-N2 -oxide-4-phenyl-1,2,5-oxadiazole using the adequate tetra-deuterated analogue. N-oxide isomer and deoxygenated analogues were also used to confirm the participation of the oxide moiety in the fragmentation process.

Li(P3C2Bu t2) reage com BrCH(SiMe3)2, via adição oxidativa, formando um novo composto organofosforado de fórmula molecular P6C4Bu t4 CHSiMe3 (1). O composto 1 foi caracterizado espectroscopicamente e sua estrutura molecular determinada através de difração de raios X de monocristais. Juntamente com 1, foi caracterizado outro composto (2) com a mesma fórmula molecular, mas apresentando uma estrutura completamente saturada.

Reaction of Li(P3C2Bu t2 ) with BrCH(SiMe3)2 results in a novel organophosphorus compound with the formula, P6C4Bu t4 CHSiMe3 (1). Compound 1 was fully characterised spectroscopically and its unique molecular structure determined by single crystal X-ray diffraction. Another isomer (2) with a saturated structure was also fully characterised.