Coordination Chemistry and Reactivity of a Cupric Hydroperoxide Species Featuring a Proximal H‑Bonding Substituent
journal contributionposted on 03.12.2012, 00:00 by Sunghee Kim, Claudio Saracini, Maxime A. Siegler, Natalia Drichko, Kenneth D. Karlin
At −90 °C in acetone, a stable hydroperoxo complex [(BA)CuIIOOH]+ (2) (BA, a tetradentate N4 ligand possessing a pendant −N(H)CH2C6H5 group) is generated by reacting [(BA)CuII(CH3COCH3)]2+ with only 1 equiv of H2O2/Et3N. The exceptional stability of 2 is ascribed to internal H-bonding. Species 2 is also generated in a manner not previously known in copper chemistry, by adding 1.5 equiv of H2O2 (no base) to the cuprous complex [(BA)CuI]+. The broad implications for this finding are discussed. Species 2 slowly converts to a μ-1,2-peroxodicopper(II) analogue (3) characterized by UV–vis and resonance Raman spectroscopies. Unlike a close analogue not possessing internal H-bonding, 2 affords no oxidative reactivity with internal or external substrates. However, 2 can be protonated to release H2O2, but only with HClO4, while 1 equiv Et3N restores 2.