Laboratoire de Chimie de Coordination.
Toulouse,
France

Outline

Our strong commitment in studies of Fischer type carbene and carbyne complexes of Manganese stems from our view that novel applications in organic synthesis should come out from their unique reactivity patterns, appearing to be quite different from those of their known group 6 metals analogs.

Modern aspects of their chemistry currently investigated in our group are simply illustrated here by two spotlights.

 The enclosed picture features a propynylidene complex of Manganese being attacked by a phosphorous probe. Our recent work has now established that the factors pre-determining the regio-selectivity of the attack by a nucleophile at the alpha or gamma carbons - and ultimately the nature of the final product - are so precisely defined that the reaction can be “programmed” toward the totally regioselective synthesis of the desired functionalized allene.

 Taking advantage of a high yield synthesis of the carbynic complex [Cp(CO)₂MnCR]⁺ (on a 30 grams scale !), we have developed an unprecedented method for the preparation of alpha-phosphinocarbenes. It consists of a simple nucleophilic attack of a primary or secondary phosphine onto to the electrophilic carbon center of the carbyne, giving a transient alpha-phosphoniocarbene, [Cp(CO)₂ Mn=C(R)P(H)R¹ R² ]⁺ which is readily de-protonated to produce the desired alpha-phosphinocarbene complex Cp(CO)₂Mn=C(R)PR¹ R².

Current research line

The recent publication of our unprecedented synthetic procedure for alpha-phosphinocarbene complexes paves the way to a thorough investigation of the chemistry of these hitherto unknown compounds.

Leading reference

 D. Valyaev, N. Lugan, G. Lavigne, N. A. Ustynyuk, Organometallics 2008, 27, 5180.
"Generation of eta1-alpha-phosphino carbine complexes and their evolution: New light on relevant isomerisation pathways."