Isolation of Carbene‐Stabilized Arsenic Monophosphide [AsP] and its Radical Cation [AsP] +. and Dication [AsP] 2+

Arsenic monophosphide (AsP) species supported by two different N‐heterocyclic carbenes were prepared by reaction of (IDipp)PSiMe 3 ( 1 ) (IDipp=1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene) with (IMes)AsCl 3 ( 2 ) (IMes=1,3‐bis(2,4,6‐trimethylphenyl)imidazolin‐2‐ylidene) to afford the dichloride [(IMes)As(Cl)P(IDipp)]Cl ( 3 ), which upon reduction with KC 8 furnished heteroleptic [(IMes)AsP(IDipp)] ( 4 ). The corresponding mono‐ and dications [(IMes)AsP(IDipp)][PF 6 ], [ 5 ]PF 6 , and [(IMes)AsP(IDipp)][GaCl 4 ] 2, [ 6 ][GaCl 4 ] 2 , respectively, were prepared by one‐electron oxidation of 4 with ferrocenium hexafluorophosphate, [Fc]PF 6, or by chloride abstraction from 3 with two equivalents of GaCl 3 , respectively. Compounds 4 – 6 represent rare examples of heterodiatiomic interpnictogen compounds, and X‐ray crystal structure determinations together with density functional theory (DFT) calculations reveal a consecutive shortening of the As−P bond lengths and increasing bond order, in agreement with the presence of an arsenic–phosphorus single bond in 4 and a double bond in 6 2+ . The EPR signal of the cationic radical [ 5 ] +. indicates a symmetric spin distribution on the AsP moiety through strong hyperfine coupling with the 75 As and 31 P nuclei.