<i>In Crystallo</i> Wolff Rearrangement of a Metalated Diazoester: Structural Confirmation of the Singlet Carbene Wolff-Intermediate
Ze‐Jie Lv, A. Fitterer, Regine Herbst‐Irmer, Serhiy Demeshko, Hendrik Verplancke, Max C. Holthausen, Sven Schneider
Abstract
High Resolution Image Download MS PowerPoint Slide The Wolff rearrangement (WR) is widely used for the synthesis of ketenes from diazoketones and -esters. Stepwise WR reactions are proposed to proceed through transient carbonylcarbene (R–C–C(O)–R′) intermediates, which so far have evaded structural characterization. Here, a Wolff metallocarbene (Pt II –C–C(O)–OEt) is reported as a fleeting intermediate in the photoinitiated fragmentation of a diazoester ligand. Frozen solution and crystal matrix isolation experiments enabled the spectroscopic, magnetic, crystallographic, and computational characterization of this highly reactive species. All methods confirmed a singlet ground state for the WR metallocarbene, which is stabilized by π interactions with the carboxyl substituent, thus complementing computational and transient spectroscopy studies for classic organic WR reactions.