Ytterbium (II) Hydride as a Powerful Multielectron Reductant

A dimeric β‐diketiminato ytterbium(II) hydride affects both the two‐electron aromatization of 1,3,5,7‐cyclooctatetraene (COT) and the more challenging two‐electron reduction of polyaromatic hydrocarbons, including naphthalene (E 0 =−2.60 V). Confirmed by Density Functional Theory calculations, these reactions proceed via consecutive polarized Yb−H/C=C insertion and deprotonation steps to provide the respective ytterbium (II) inverse sandwich complexes and hydrogen gas. These observations highlight the ability of a simple ytterbium(II) hydride to act as a powerful two‐electron reductant at room temperature without the necessity of an external electron to initiate the reaction and avoiding radicaloid intermediates.