Acyl‐Phosphide Anions via an Intermediate with Carbene Character: Reactions of K[PtBu2] and CO.

The analogy of the reactivity of group 1 phosphides to that of FLPs is further demonstrated by reactions with CO, affording a new synthetic route to acyl‐phosphide anions. The reaction of [K(18‐crown‐6)][PtBu2] (1) with CO affords [(18‐crown‐6)K⋅THF2][Z‐tBuP=C(tBu)O] (2⋅THF2) as the major product, and the minor product [K6(18‐crown‐6)][(tBu2PCO)2]3 (3). Species 2 reacts with either BPh3 or additional CO to give [K(18‐crown‐6)][(Ph3B)tBuPC(tBu)O] (4) and [K(18‐crown‐6)][(OCtBu)2P] (5), respectively. The acyl‐phosphide anion 2 is thought to be formed by a photochemically induced radical process involving a transient species with triplet carbene character, prompting 1,2‐tert‐butyl group migration. A similar process is proposed for the subsequent reaction of 2 with CO to give 5. [ABSTRACT FROM AUTHOR]