In addition to oxometal [Mn+O] and imidometal [Mn+NR] units, transient metal-iodosylarene [M(n-2)+-OIPh] and metal-iminoiodane [M(n-2)+-N(R)IPh] adducts are often invoked as a possible "second oxidant" responsible for the oxo and imido group transfer reactivity. Although a few metal-iodosylarene adducts have been recently isolated and/or spectroscopically characterized, metal-iminoiodane adducts have remained elusive. Herein, we provide UV-Vis, EPR, NMR, XAS and DFT evidence supporting the formation of a metal-iminoiodane complex 2 and its scandium adduct 2-Sc. 2 and 2-Sc are reactive toward substrates in the hydrogen-atom and nitrene transfer reactions, which confirm their potential as active oxidants in metal-catalyzed oxidative transformations. Oxidation of para-substituted 2,6-di-tert-butylphenols by 2 and 2-Sc can occur by both coupled and uncoupled proton and electron transfer mechanisms; the exact mechanism depends on the nature of the para substituent.
Bibliographical noteFunding Information:
W. N. acknowledges financial support from the NRF of Korea through the CRI (NRF-2012R1A3A2048842) and GRL (NRF-2010-00353). JE is thankful to the NAP fellowship of the Nanyang Technological University.
© 2016 The Royal Society of Chemistry.