Electrophilic Functionalization of a Hexaphosphabenzene Ligand in [(Cp*Mo)2(µ,η6 : 6-P6)].

ABSTRACT

The electrophilic functionalization of the triple-decker sandwich complex [{Cp*Mo}2(µ,η66-P6)] (A) and its mono-oxidized counterpart [{Cp*Mo}2(µ,η66-P6)][SbF6] (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 [{Cp*Mo}2{(µ,η3 3-P3)(µ,η1 1 1 1-1,3-(SePh)2-2-Br-P3)}][TEF] (1), [{Cp*Mo}2(µ,η3 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,η44-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-µ4,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.