Electrophilic Functionalization of a Hexaphosphabenzene Ligand in [(Cp*Mo)(μ,η-P)].

The electrophilic functionalization of the triple-decker sandwich complex [{CpMo}(μ,η-P)] (A) and its mono-oxidized counterpart [{CpMo}(μ,η-P)][SbF] (B) with reactive main-group electrophiles as well as radical scavengers is shown to be a reliable method for the selective functionalization of the hexaphosphabenzene ligand. Depending on the electrophile used, the regioselectivity of the functionalization can be adjusted. Using group 16 electrophiles, the trisubstituted compounds [{CpMo}{(μ,η-P)(μ,η-1,3-(SePh)-2-Br-P)}][TEF] (1), [{CpMo}(μ,η-P)(μ,η-1,2,3-(EPh)-P)][SbF] (E=S (2), Se (3)) as well as the side product [{CpMo}(μ,η-P)(μ,η-P(SPh))][SbF] (4) are obtained. By switching to phosphenium ions as group 15 electrophiles, the ring-inserted products [{CpMo}(μ,η-PR)][TEF] (R=Cy (5), Pr (6)) are isolated, showing an unprecedented PR structural motif. Furthermore, the reaction with MeOTf yields the dimeric [{CpMo}(1,4-Me-μ,η-P)(μ,η-P)][TEF] (7) as the first example of a complex featuring two interconnected cyclo-P middle deck ligands. Finally, by combination of the methylation step with PhSe, the mixed group 14/16 complex [{CpMo}{(μ,η-P)(μ,η1,2-(SePh)-3-Me-P)}][OTf] (8) is obtained.