Hydrido carbonyl complexes of osmium(II) and ruthenium(II) containing polypyridyl ligands

Article abstract of DOI:10.1021/om00086a016

Several different synthetic routes have been explored to produce hydrido complexes of Os(II) and Ru(II) containing polypyridyl ligands. The resulting complexes, the majority of which contain coordinated CO, are of three types: cis-[M(chelate)₂(CO)H]⁺, trans-[Os(chelate)(PPh₃)₂(CO)H]⁺, and [Os(chelate)(diphos)(PR₃)H]⁺ (where M = Ru or Os and chelate is, for example, 2,2′-bipyridine or 1,10-phenanthroline or a related ligand). The electronic, infrared, and NMR spectral properties of the complexes are discussed along with the redox properties of their ground and excited states. An important observation is that the hydride ligand endows the metal to ligand charge-transfer (MLCT) excited states of some of the complexes with strong reducing properties. The ground-state chemistry of the complexes is discussed especially with regard to their use as synthetic precursors to new, highly oxidizing, long-lived MLCT excited states of Os(II), e.g., [Os^III(bpy^-.)(bpy)(CO)(CH₃CH)]²⁺.