The new phenol-imidazole pro-ligands RLH react with Co(BF 4)2·6H2O in the presence of Et 3N to form the corresponding [CoII(RL) 2] compound (R = Ph (1), PhOMe (2), or Bz (3)). Also, BzLH, reacts with Co(II) in the presence of Et3N and H2O2 to form [CoIII(BzL) 3] (4). The structures of l·2.5MeCN, 2·2DMF, 3·4MeOH, and 4·4DMF have been determined by X-ray crystallography. 1, 2, and 3 each involve Co(II) bound to two N,O-bidentate ligands with a distorted tetrahedral coordination sphere; 4 involves Co(III) bound to three N,O-bidentate ligands in a mer-N3O3 distorted octahedral geometry. [CoII(RL)2] (R = Ph or PhOMe) undergo two, one-electron, oxidations. The products of the first oxidation,  + and +, have been synthesised by the chemical oxidation of 1 and 2, respectively; these cations, formulated as [Co II(RL)(RL)2]+, comprise one phenoxyl radical and one phenolate ligand bound to Co(II) and are the first phenoxyl radical ligand complexes of tetra-coordinated Co(II). 4 undergoes two, one-electron, ligand-based oxidations, the first of which produces  +, [CoIII(BzL)(BzL)2]+. Unlike [l]+and +, product of the one-electron oxidation of [CoII(BzL)2], +, is unstable and decomposes to produce +. These studies have demonstrated that the chemical properties of [MII(RL)(RL) 2]+ (M = Co, Cu, Zn) are highly dependent on the nature of both the ligand and the metal centre.
ASJC Scopus subject areas
- Inorganic Chemistry