Phospha‐ and Arsaalkenes RE=C(NMe₂)₂ (E = P, As) as Novel Phosphinidene‐ and Arsinidene‐Transfer Reagents

Abstract

Phosphinidenes (phosphanylidenes) (RP) are electronically and coordinatively unsaturated phosphorus compounds, which, as six-electron species, are formally analogous to the more familiar carbenes and nitrenes. In contrast to carbenes (CR 2 ), the extremely reactive phosphinidenes cannot be isolated without decomposition. Thus, our knowledge on phosphinidenes is mainly limited to trapping reactions and quantum-chemical calculations. There are a number of synthetic methods for phosphinidenes available, for example photolysis or thermolysis of cyclic phosphanes and oligophosphanes,

Dehydrogenative Bond-Forming Catalysis Involving Phosphines

“…There has been a dramatically increased number of isolated transition-metal complexes with terminal phosphinidene ligands [75]. With this plethora of new complexes, a rich variety of stoichiometric reaction chemistry of the M=P bond has emerged [72,73,[75][76][77][78][79][80][81]. This new chemistry is also suggestive of the potential for new catalysis associated with the phosphinidene moiety.…”

“…This new chemistry is also suggestive of the potential for new catalysis associated with the phosphinidene moiety. Transient phosphinidene complexes have been responsible for making numerous otherwise difficult to prepare organophosphorus species synthetically accessible through stoichiometric transformations [2,75,77]. Such well-developed chemistry associated with transient phosphinidene complexes is further suggestive of the potential for novel catalytic chemistry.…”

“…There is extensive and valuable synthetic chemistry associated with transient metal phosphinidene species [2,75,77], yet despite recent improvements, molecular precursors [109] to these phosphinidene complexes are still more difficult to access synthetically than primary phosphines, many of which are commercially available.…”

“…The observation of a phosphinidene complex is not unusual. In the preparation of neutral phosphinidene complexes, elimination of phosphine or methane is an effective synthetic procedure [72,75,77]. The likelihood that such a complex is present in the reaction is high, but it is uncertain if that phosphinidene species is catalytically active or simply a spectator in the catalysis.…”

Nucleophilic Phosphinidene Complexes: Access and Applicability

“…However, terminal transition-metal-complexed phosphinidenes ([L n M=PÀR], B; Scheme 1), which are the phosphorus analogues of the well-established carbene complexes, appear to be valuable synthons with rapidly expanding chemistries. [7][8][9][10] These advances were enabled by the discovery in the 1980s of the transient electrophilic species [(OC) 5 W = P À Ph] by the group of Mathey [11] and of the isolable nucleophilic phosphinidene complex [Cp 2 W=PÀMes*] by Lappert and co-workers (Cp = C 5 H 5 , Mes* = 2,4,6-tBuC 6 H 2 ). [12] Illustrative of the ensuing rapid progress in this field are two reviews by Cowley, one published in 1988, entitled "The Quest for Terminal Phosphinidene Complexes" [13a] and the other in 1997 "Terminal Phosphinidene and Heavier Congeneric Complexes.…”