The lithium effect in ketenyl anion chemistry.

Ketenyl lithium compounds of type [RC(Li)CO] (with R = Ph 2 P(E), E = O, S, Se) were found to exhibit lower thermal stabilities than their potassium analogues due to the stronger coordination of the oxygen of the ketene moiety to the harder metal cation, resulting in a more pronounced ynolate character. Using additional ligands allows manipulation of the O-Li interaction, thereby influencing the stability and reactivity of the ketenyl anions.