From Neutral Diarsenes to Diarsene Radical Ions and Diarsene Dications

Diarsene [L(MeO)GaAs] 2 (L=HC[C(Me)N(Ar)] 2 , Ar=2,6‐ i Pr 2 C 6 H 3 , 4 ) reacts with MeOTf and Me NHC ( Me NHC=1,3,4,5‐tetra‐methylimidazol‐2‐ylidene) to the diarsene [L(TfO)GaAs] 2 ( 5 ) and the carbene‐coordinated diarsene [L(MeO)GaAsAs( Me NHC)Ga(OMe)L] ( 6 ). The NHC‐coordination results in an inversion of the redox properties of the diarsene 4 , which shows only a reversible reduction event at E 1/2 =−2.06 V vs Fc 0/+1 , whereas the carbene‐coordinated diarsene 6 shows a reversible oxidation event at E 1/2 =−1.31 V vs Fc 0/+1 . Single electron transfer reactions of 4 and 6 yielded [K[2.2.2.]cryp][L(MeO)GaAs] 2 ( 8 ) and [L(MeO)GaAsAs( Me NHC)‐Ga(OMe)L][B(C 6 F 5 ) 4 ] ( 9 ) containing the radical anion [L(MeO)GaAs] 2 ⋅ − ( 8 ⋅ − ) and the NHC‐coordinated radical cation [L(MeO)GaAsAs( Me NHC)Ga(OMe)L]⋅ + ( 9 ⋅ + ), respectively, while the salt‐elimination reaction of the triflate‐coordinated diarsene 5 with Na[B(C 6 F 5 ) 4 ] gave [LGaAs] 2 [B(C 6 F 5 ) 4 ] 2 ( 11 ) containing the dication [LGaAs] 2 2+ ( 11 2+ ). Compounds 1 – 11 were characterized by 1 H and 13 C NMR, EPR ( 8 , 9 ), IR, and UV‐Vis spectroscopy and by single crystal X‐ray diffraction (sc‐XRD). DFT calculations provided a detailed understanding of the electronic nature of the diarsenes ( 4 , 6 ) and the radical ions ( 8 ⋅ − , 9 ⋅ + ), respectively.