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Osmium Hydrazido and Dinitrogen Complexes
George M. Coia1, Martin Devenney, Peter S. White
1Chemistry Section, Laboratory of Comparative Carcinogenesis, National Cancer Institute, Frederick Cancer Research and Development Center, Frederick, Maryland 21702.
Inorganic Chemistry
|May 21, 1997
Summary
This study details the electrochemical oxidation of an osmium complex with amines, forming new hydrazido complexes. These complexes exhibit bent coordination and undergo reversible redox reactions, providing insights into osmium-amine chemistry.
Area of Science:
- Inorganic Chemistry
- Electrochemistry
- Coordination Chemistry
Background:
- Osmium complexes with polypyridyl ligands are of interest for their redox properties.
- Understanding the reactivity of osmium complexes with amines is crucial for developing new catalytic systems.
Purpose of the Study:
- To investigate the electrochemical oxidation of [Os(tpy)(bpy)(NH3)](PF6)2 (1) in the presence of various amines.
- To characterize the resulting osmium-amine complexes, including their structures and redox behavior.
Main Methods:
- Electrochemical oxidation and reduction in aqueous and non-aqueous solutions.
- X-ray crystallography for structural determination.
- Cyclic voltammetry for kinetic studies.
Main Results:
- Oxidation of complex 1 with secondary aliphatic amines yielded [Os(tpy)(bpy)(NNR2)](PF6)3 (3) (n=4.6-5.0).
- Complex 3 was reduced to [Os(tpy)(bpy)(NNR2)](PF6)2 (2) (n=1.0), with bent hydrazido(2-) coordination observed in crystal structures.
- Protonation of 2 yielded hydrazido(1-) complexes, and reduction of 2 at low pH produced complex 1.
Conclusions:
- The study elucidates the electrochemical pathways for osmium-amine complex formation and transformation.
- The characterized hydrazido complexes demonstrate rich redox chemistry and structural features.
- This work contributes to the understanding of osmium coordination chemistry and its potential applications.