Electrophilic Functionalization of a Hexaphosphabenzene Ligand in [(Cp*Mo)₂(μ,η^6 : 6‐P₆)]

Abstract

The electrophilic functionalization of the triple‐decker sandwich complex [{Cp*Mo}2( μ , η 6:6 ‐P6)] (A) and its mono‐oxidized counterpart [{Cp*Mo}2( μ , η 6:6 ‐P6)][SbF6] (B) with reactive main‐group electrophiles as well as radical scavengers is a reliable method for the selective functionalization of the hexaphospha‐benzene ligand. Depending on the electrophile used, the regioselectivity of the functionalization can be adjusted. Using group 16 electrophiles, the trisubstituted compounds [{Cp*Mo}2{( μ , η 3:3 ‐P3)( μ , η 1:1:1:1 ‐1,3‐(SePh)2‐2‐Br‐P3)}][TEF] (1), [{Cp*Mo}2( μ , η 3:3 ‐P3)( μ,η1:1:1:1‐1,2,3‐(EPh)3‐P3)][SbF6] (E = S (2), Se (3)) as well as the side product [{Cp*Mo}2(μ,η4:4‐P4)(μ,η1:1‐P(SPh)2)][SbF6] (4) are obtained. By switching to phosphenium ions as group 15 electrophiles, the ring‐inserted products [{Cp*Mo}2(μ,η3:3:2:2‐P7R2)][TEF] (R = Cy (5), iPr (6)) are isolated, showing an unprecedented P7R2 structural motif. Furthermore, the reaction with MeOTf yields the dimeric [{Cp*Mo}4(1,4‐Me2‐μ3,η1:1:1:1:1:1‐P6)(μ,η3:3‐P3)2][TEF]2 (7) as the first example of a complex featuring two interconnected cyclo‐P6 middle deck ligands. Finally, by combination of the methylation step with Ph2Se2, the mixed group 14/16 complex [{Cp*Mo}2{(μ,η3:3‐P3)(μ,η1:1:1:11,2‐(SePh)2‐3‐Me‐P3)}][OTf] (8) is obtained.