Unambiguous Spectroscopic Characterization of a Gold Difluorocarbene

Gold-(I) carbenes, defined as [LAuCR₂]⁺, are key intermediates in catalysis. Their isolation is challenging due to the high electrophilic character of the carbene that cannot be tempered solely by π-backdonation from gold. Among those, the simple difluorocarbene complex has been invoked in several studies, but attempts to isolate it have failed, while its identification remains questionable. In this study, we report the unambiguous spectroscopic characterization of the gold difluorocarbene complex [P-AuCF₂]⁺, providing key insights into its structural and electronic features. The kinetic stabilization of the carbene was only possible owing to the shielding offered by a congested and cavity-shaped phosphine that prevents decomposition under strict anhydrous conditions. Besides, the nature of the anion is key to provide further thermal stability for prolonged times.