Synthesis and characterization of a tetranuclear ruthenium(II)-oxo-hydroxo complex and its cooperative activity for small molecule transformations
Abstract
Allostetic and cooperative enzymes effectively catalyze and regulate a variety of biochemical reactions through induced conformational changes at their active sites. In an attempt to mimic the high chemio- and regioselectivity of these enzymes, recent research has focused on the design and synthesis of synthetic cooperative catalysts. Polynuclear, transition-metal complexes with multiple, adjacent active metal centers are ideal candidates for the construction of catalysts that display cooperative and allosteric activity. We wish to report the synthesis and complete characterization of a tetranuclear, Ru(II)-oxo-hydroxo complex, {[((PCy3 )(CO)Ru(H)4 (μ 3 -OH)(μ2 -OH)(μ4 - O)}, 1 . The tetranuclear complex was found to have high catalytic activity and selectivity For both the alcohol oxidation and nitrite hydration reactions. Throughout the course of the mechanistic investigation of the reactions, we found compelling evidence for the cooperative activity of 1 . Extensive kinetic studies of both mechanisms confirmed the existence of both cooperative and non-cooperative mechanisms. Using spectroscopic, mechanistic, and structural techniques, we have determined certain factors which govern the appearance of the cooperative activity. By understanding the intricacies of the cooperative activity of 1 , we can further attenuate the tetranuclear complex in order to fully exploit the cooperative activity of 1 for a wide variety of small molecule transformations.
This paper has been withdrawn.