Cationic cobalt(I) dinitrogen complexes with a strong-field tridentate pincer ligand were prepared, and the oxidative addition of polar and nonpolar bonds was studied. Addition of H 2 to [( iPr PNP)Co(N 2 )] + ( iPr PNP = 2,6-bis((diisopropylphosphaneyl)methyl)pyridine) in deuterated tetrahydrofuran (THF) resulted in rapid oxidative addition and formation of the cis-Co(III) dihydride complex, cis-[( iPr PNP)Co(H) 2 L] + , where L = THF or N 2 . The addition of H 2 was reversible as evidenced by the dynamics observed by variable-temperature 1 H NMR spectroscopy and the regeneration of [( iPr PNP)Co(N 2 )] + upon exposure to dinitrogen. In contrast, addition of HBPin (Pin = pinacolato), B 2 Pin 2 , and aryl halides resulted in the formation of net one-electron oxidation products: cationic Co(II)-boryl and Co(II)-halide/aryl complexes, respectively. All products were structurally characterized by X-ray crystallography, and the electronic structures were determined by a combination of magnetic moment measurements, electron paramagnetic resonance spectroscopy, and density functional theory calculations. Monitoring the addition of HBPin to [( iPr PNP)Co(N 2 )] + provided evidence for a transient Co(III) oxidative addition product that likely undergoes comproportionation with the cobalt(I) starting material to generate the observed Co(II) products.
All Science Journal Classification (ASJC) codes
- Inorganic Chemistry
- Physical and Theoretical Chemistry
- Organic Chemistry