Direct functionalization of white phosphorus with anionic dicarbenes and mesoionic carbenes: facile access to 1,2,3-triphosphol-2-ides.

A series of unique CP-ring compounds [(ADC)P] (ADC = ArC{(DippN)C}; Dipp = 2,6-iPrCH; Ar = Ph , 3-MeCH , 4-MeCH , and 4-MeNCH ) are readily accessible in an almost quantitative yield by the direct functionalization of white phosphorus (P) with appropriate anionic dicarbenes [Li(ADC)]. The formation of 1,2,3-triphosphol-2-ides () suggests unprecedented [3 + 1] fragmentation of P into P and P. The P cation is trapped by the (ADC) to give , while the putative P anion reacts with additional P to yield the LiP species, a useful reagent in the synthesis of organophosphorus compounds. Remarkably, the P fragmentation is also viable with the related mesoionic carbenes (iMICs) (iMIC = ArC{(DippN)CCH}, i stands for imidazole-based) giving rise to . DFT calculations reveal that both the CN and CP-rings of are 6π-electron aromatic systems. The natural bonding orbital (NBO) analyses indicate that compounds are mesoionic species featuring a negatively polarized CP-ring. The HOMO-3 of is mainly the lone-pair at the central phosphorus atom that undergoes σ-bond formation with a variety of metal-electrophiles to yield complexes [{(ADC)P}M(CO) ] (M = Fe, = 4, Ar = Ph or 4-Me-CH ; M = Mo, = 5, Ar = Ph ; M = W, = 5, Ar = 4-MeNCH ).