Monomeric β-Diketiminato Group 13 Metal Dipnictogenide Complexes with Two Terminal EH₂ Groups (E=P, As)

The pnictogenyl Group 13 compounds (Dipp₂ Nacnac)M[E(SiMe₃ )₂ ]Cl and (Dipp₂ Nacnac)M(EH₂ )₂ (Dipp₂ Nacnac=HC[C(Me)N(Ar)]₂ , Ar: Dipp=2,6-iPr₂ C₆ H₃ ; M=Al, Ga, In; E=P, As) were successfully synthesized. The salt metathesis between (Dipp₂ Nacnac)MCl₂ and LiE(SiMe₃ )₂ only led to monosubstituted compounds (Dipp₂ Nacnac)M[E(SiMe₃ )₂ ]Cl [E=P, M=Ga(1), In (2); E=As, M=Ga (3), In (4)], regardless of the stoichiometric ratios used. In contrast to the steric effect of the SiMe₃ groups in 1-4, the reactions of the corresponding halides with LiPH₂ ⋅DME (or KAsH₂ ) facilely yielded the dipnictogenide compounds (Dipp₂ Nacnac)M(EH₂ )₂ (E=P, M=Al (5), Ga (6), In (7); E=As, M=Al (8), Ga (9)), avoiding the use of flammable and toxic PH₃ and AsH₃ for their synthesis. The compounds 5-9 are the first examples of monomeric Group 13 diphosphanides and diarsanides in which the metal center is bound to two terminal PH₂ and AsH₂ groups, respectively. In contrast to the successful synthesis of the indium diphosphanide (Dipp₂ Nacnac)In(PH₂ )₂ , the reaction of (Dipp₂ Nacnac)InCl₂ with KAsH₂ led to an indium mirror due to the instability of the target product.