C–P bond forming reactivity of N-heteropentacene: Isolation and characterization of a phospho-ylide complex of ruthenium(II)

In an unusual reaction of H2L2 (H2L2 = N-heteropentacene) with Ru(PPh3)3Cl2 a phospho-ylide ruthenium(II) complex (1) was obtained via unprecedented chemical transformations of the conjugate base [L2]2−. A bidentated phospho-ylide ligand is formed with concomitant aromatic ring hydroxylation and new C–P bond formation reactions. The new ligand, binds to RuII as a neutral N, O-donor. Crystal structure determination by single crystal X-ray diffraction has been used to characterize the compound. The phospho-ylide Ru(II) description of the complex was established based on 13C as well as 31P NMR studies. The complex shows rich spectral and redox properties. UV–Vis–NIR spectrum consisted of multiple low-energy transitions in the visible and near IR regions. Preliminary density functional theory calculations were employed to understand the electronic structure and to assign the spectral transitions. Cyclic voltammogram and EPR-spectrum of the electrogenerated oxidized compound are reported and used to characterize the redox properties.

Graphical abstractA ruthenium(II) complex of a phospho-ylide ligand was isolated from the chemical reaction of a N-heteropentacene compound and Ru(PPh3)3Cl2. The reaction occurs via a series of unprecedented chemical transformations including hydroxylation as well as C–P bond formation at the heteropentacene ring.Figure optionsDownload full-size imageDownload as PowerPoint slide