This dissertation comprises the investigation of two subjects in the field of dimetal paddlewheel-type compounds containing metal-metal bonds: unsolvated transition metal carboxylates and triply bonded divanadium compounds. The first subject is very mature; dichromium tetraacetate was first synthesized in 1844, and hundreds of dimetal tetracarboxylates have been structurally characterized to date. A general question concerning the complexes of the type M2L4-Xn (where n = 0 to 2) is the extent to which the M-M distances are influenced by the presence of axial ligands, X. However, virtually none of the carboxylato complexes crystallize without axial ligands. In the solid state, in the absence of a coordinating solvent, the dimetal units often act as axial ligands to one another. In order to exclude axial coordination, both from donor solvent molecules, and from the aggregation of M24+ units, we have successfully used the bulky 2,4,6-triisopropylbenzoate ligand to bridge the dimetal core. We have investigated the triisopropylbenzoato complexes of some metals which are known for their ability to form a vast array of tetracarboxylato complexes, namely chromium, copper, molybdenum, and rhodium, and have found that these novel compounds display some interesting structural and chemical properties. The second subject of this dissertation is much more contemporary. Although compounds containing multiple bonds between metal atoms have been known since 1964, the first triply-bonded divanadium compound was not synthesized until 1992, and only two additional compounds of this type have been made in the intervening ten years. In order to extend this chemistry, several additional compounds containing a triply bonded V24+ core have recently been characterized. In our study of these compounds, we have discovered the first example of a stable paddlewheel-type compound with a M23+ core.

Neste estudo, foram sintetizados complexos de ródio com aminoácidos e aminoácidos N-protegidos. Os compostos sintetizados foram caracterizados por análise elementar, espectrofotometria nas regiões do infravermelho e ultravioleta-visível, susceptibilidade magnética, ressonância magnética nuclear de próton e calorimetria exploratória diferencial. As técnicas analíticas utilizadas permitiram avaliar a estrutura dos complexos de ródio obtidos. Nos complexos sintetizados com aminoácidos, a ligação ocorreu pelos átomos de nitrogênio do grupamento amina e pelo oxigênio do grupo carboxila, formando anéis quelato de cinco membros, estrutura esta distinta da apresentada por compostos diméricos de ródio (II). Este modo de coordenação típico de carboxilatos de ródio dimérico, foi alcançado fazendo-se o bloqueio do grupamento amino, direcionando assim a coordenação do aminoácido, aos átomos de ródio, através dos dois oxigênios da carboxila. Numa etapa posterior, o grupo protetor foi removido por ataque ácido, tomando o complexo, anteriormente solúvel em solventes apoiares, totalmente solúvel em água, sendo mantida a estrutura de gaiola. Partindo-se dos complexos de ródio (II) sintetizados com aminoácidos N-bloqueados, foram obtidos adutos com o ácido isonicotínico, que se mostraram mais hidrossolúveis do que os complexos iniciais. Os compostos [Rh2(Boc-Gly)4)(I), [Rh2(Boc-L-Ala)4)(II) e seus respectivos adutos com o ácido isonicotínico foram submetidos a ensaios biológicos in vitro, onde foi avaliada a citotoxicidade destes sobre células tumorais K562, U937 e de tumor de Ehrlich. O aduto [Rh2(Boc-L-Ala)4](AIN)2(III) também foi submetido a um ensaio in vivo, de sobrevida. Camundongos portadores de tumor ascite de Ehrlich, tratados com solução do complexo (III), tiveram um aumento significativo de sobrevida, com formação de tumor sólido. Os complexos (I), (II), [Rh2(Boc-L-Val)4)(IV), [Rh2(Boc-L-Leu)4](V) e [Rh2(Boc-D-Phe)4)(VI) foram avaliados quanto ao seu potencial catalítico, em reações de hidrogenação. Os resultados foram expressos em termos de conversão de substrato em função do tempo de reação, número de rotação, freqüência de rotação e curvas TT x TTG. O complexo (I) apresentou atividade semelhante ao acetato de ródio (II), que foi utilizado como complexo de referência. Os demais compostos, (II), (V) e (VI) mostraram-se mais ativos que o acetato de ródio (II), nas reações de hidrogenação de hexeno-1 em etanol. / In this study, rhodium complexes were synthesized using amino acids and N-protected amino acids as ligands. The synthesized compounds were characterized by elemental analysis, IR and UVVis spectroscopy, magnetic susceptibility, proton magnetic nuclear resonance and diferential scanning calorimetry. The used analytical techniques allowed us to evaluate the structure of the obtained rhodium complexes. In the amino acids complexes, the binding occured through nitrogen atoms of the amino group and through the oxygen atom of the carboxyl group, forming chelate rings of five members, being these structures different from those presented by rhodium (II) carboxylates. This coordination mode was achieved protecting the amino group. In a next stage, the protecting group was removed by acid attack, turning the previously soluble in apolar solvents complex, totally soluble in water, being maintained the cage structure. From the N-protected amino acids rhodium (II) complexes synthesized, we obtained the isonicotinic acid adducts, more hydrossoluble than the original complexes. Antitumor activity of rhodium complexes [Rh2(Boc-Gly)4](I), [Rh2(Boc-L-Ala)4](II) and its isonicotinic acid adducts, was evaluated in vitro ( cell cultures K562, U937 and Ehrlich) and the compound [Rh2(Boc-L-Ala)4](AIN)2(III) was also submitted to a in vivo assay. Mices bearing Ehrlich ascite tumor, when treated with complex (III) solution, had a significant increase life span, with formation of solid tumor. The complexes (I), (II), [Rh2(Boc-L-Val)4](IV), [Rh2(Boc-L-Leu)4](V) and [Rh2(Boc-D-Phe)4](VI) were also tested in catalytic hydrogenation reactions. The results were expressed in terms of substrate conversion, turnover number, turnover frequency and TT x TTG curves. The complex (I) presented catalytic activity similar to the rhodium acetate (II), that was used as reference complex. The other compounds, (II), (V) and (I) exhibited improved catalytic behavior compared to rhodium (II) acetate in hydrogenation reactions using 1-hexene as substrate.