Redox regulation in ruthenium complexes containing β-diketonate ligands and 2,6-bis(N-pyrazolyl)pyridine and its methyl-substituted derivatives

Abstract

A new family of complexes of the general formula [Ru(Me_nbpp)(R₂mal)L] has been prepared, where Me_nbpp is 2,6-bis(N-pyrazolyl)pyridine or a methyl-substituted derivative (n = 0, 2, or 4), R₂mal is a 1,3-substituted β-diketonate, and L is chloride or an N-heterocycle ligand. The bidentate β-diketonate ligand substantially lowers the Ru(III/II) potentials relative to analogous polypyridyl complexes. The synthetic scheme presented here can be used to prepare a wide variety of complexes for which the Ru(III/II) couple can be systematically and rationally tuned over a range of 600 mV by varying the number of methyl groups on the 2,6-bis(N-pyrazolyl)pyridine ligand, and/or the substituents on the β-diketonate ligands. Substitution at the sixth coordination site allows for further synthetic versatility of these complexes, including bridging ligands, such that these complexes may serve as precursors to bimetallic complexes.

References

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