Synthesis and Characterization of Ruthenium(II) and Platinum(IV) Complexes with Anionic Heteroatomic Ligands

Abstract

Isolated and fully characterized complexes of late transition metals in low oxidation states possessing amido and alkoxo ligands are relatively rare. These ligands often exhibit nucleophilic and/or basic reactivity. This reactivity is due, at least in part, to the disruption of ligand to metal à €-bonding. Reports of early transition metals with low d-electron counts with imido ligands facilitating C-H activation suggest that if later transition metals with amido or aryloxo ligands can be isolated, C-H activation reactivity may be observed. Ruthenium(II) complexes that catalyze the H/D exchange of N-H and O-H protons at anilido and hydroxo ligands, respectively, with deuterated solvents have been reported, and studies of related systems could shed significant light on C-H activation in these types of reactions. Observing changes in the rate of C-H activation based on specific changes to transition metal complexes could give insight into the creation of highly active C-H activation catalysts. Presented here are synthetic efforts toward late transition metal complexes with formally anionic heteroatomic ligands. The synthesis and initial characterization of [EpRu(Cl)(PPh₃)(NCMe)][Cl], [EpRu(py)₂Cl][Cl], [EpRu(py)₂Cl][Cl], [EpRu(OHMe)(PMe3)(Cl)][BAr’₄] are reported {Ep = 1,1,1-tris(pyrazolyl)ethane, py = N-pyridine, Ar’ = 3,5-(CF₃)-C₆H₃}. The lack of solubility yielded these complexes ineffective for further synthetic manipulation. Additionally presented is the synthesis and characterization of (tbpy)Pt(Me)₂(I)₂ and (tbpy)Pt(Me)(NHPh)(I)₂ (tbpy = 4,4’-tert-butyl-2,2’-bipyridine). Attempted syntheses of (tbpy)Pt(NHPh)₂(I)₂ and (tbpy)Pt(Cl)(NHPh)(I)₂ are also reported. Initial reactivity of (tbpy)Pt(Me)₂(I)₂ and the decomposition of (tbpy)Pt(Me)(NHPh)(I)₂ are further reported.