Boosting Low‐Valent Aluminum(I) Reactivity with a Potassium Reagent

The reagent RK [R=CH(SiMe(3))(2) or N(SiMe(3))(2)] was expected to react with the low‐valent ((DIPP)BDI)Al ((DIPP)BDI=HC[C(Me)N(DIPP)](2), DIPP=2,6‐iPr‐phenyl) to give [((DIPP)BDI)AlR](−)K(+). However, deprotonation of the Me group in the ligand backbone was observed and [H(2)C=C(N‐DIPP)−C(H)=C(Me)−N−DIPP]Al(−)K(+) (1) crystallized as a bright‐yellow product (73 %). Like most anionic Al(I) complexes, 1 forms a dimer in which formally negatively charged Al centers are bridged by K(+) ions, showing strong K(+)⋅⋅⋅DIPP interactions. The rather short Al–K bonds [3.499(1)–3.588(1) Å] indicate tight bonding of the dimer. According to DOSY NMR analysis, 1 is dimeric in C(6)H(6) and monomeric in THF, but slowly reacts with both solvents. In reaction with C(6)H(6), two C−H bond activations are observed and a product with a para‐phenylene moiety was exclusively isolated. DFT calculations confirm that the Al center in 1 is more reactive than that in ((DIPP)BDI)Al. Calculations show that both Al(I) and K(+) work in concert and determines the reactivity of 1.