Synthesis, Structure, and Reactivity of Carbodiphosphoranes, Carbodicarbenes, and Related Species

Abstract

The unique electronic distribution in carbodiphosphoranes has attracted the attention of chemists early since their first isolation. These molecules can be seen as two simultaneous ylide functionalities localized at the same carbon atom; thus, their central carbon possesses two perpendicular electron pairs available for coordination. Recent theoretical studies point that the bonding situation in these compounds is best described using a captodative model; that means, in terms of donor acceptor interactions . Hence, carbodiphosphoranes can be seen as C(0) atoms stabilized by two flanking phosphines. Although not always free of controversy, the fact is that this analysis is extremely useful to predict and understand the reactivity of carbodiphosphoranes of different structure as well as that of analogous molecules such as carbodicarbenes, carbon suboxide, and mixed systems. This chapter reviews theoretical and experimental research on carbodiphosphoranes C(PR3)2 and related compounds of formula C(L)2 as both, free molecules and ligands in transition metal or main group coordination complexes. Special emphasis will be given to highlight the unique reactivity derived from localizing two electron pairs at the same carbon atom.