Synthetic models for inorganic intermediates in the oxidation of hydrocarbons by high valent vanadium and chromium oxo complexes. Low-coordinate nitrosyl complexes of iron, cobalt and nickel for nitric oxide activation

We are exploring new transition metal complexes related to the structurally simple chromyl chloride that serve as synthetic models for the inorganic intermediates involved in the oxidation of hydrocarbons by high valent metal-oxo complexes. Our strategy has involved the use of bulky, electron-poor 2,6-diarylylbenzoates as ancillary ligands. The molecular shape provided by the two diarylbenzoate ligands should sterically discourage bridging interactions between metal centers that could lead to oligomerization, enabling the isolation of the reduced metal species and their identification by traditional solution techniques and by X-ray crystallography. We have studied carboxylate complexes of V and Cr as synthetic models for inorganic intermediates in the oxidation of hydrocarbons by high valent, first row transition metal oxo complexes. By using sterically hindered, electron-poor 2,6-diarylbenzoate ligands (ArCEEH, E = O, S), new mono- and dinuclear chromium and vanadium carboxylate complexes were prepared and structurally characterized. We have explored the effect that sterically-hindered, electron-poor 2,6-diarylbenzoates have on the reactivity of d(0), terminal metal-oxo moieties.;Due to the fact that NO is an important signaling molecule in biological systems, the chemistry of transition metal nitrosyl complexes has received increased attention in recent years. Many biomimetic metal nitrosyl complexes of Fe-Cu, both heme analogues as well as non-heme have been synthesized and provide insight into the active sites of such enzymes. There are very few examples of transition metal nitrosyl complexes with a coordination number of three. We aim to sterically protect the metal centers of interest with bulky ligands such as beta-diketiminates, a family of chelating, monoanionic anicilary ligands well-suited for later, first row transition metal chemistry. The recent synthesis in our laboratory of low-valent metal complexes that employ beta-diketiminates as well as a labile ligand sparked our interest to prepare metal nitrosyl complexes. Our goals are to explore the chemistry of NO in well-defined low-coordinate molecular environments to uncover new insights into its reactivity. We have synthesized and characterized mono and dinitrosyl complexes of Fe, Co and Ni and studied their reactivity towards reactions involving the activation of coordinated NO. (Abstract shortened by UMI.)...