Synthesis and EPR/UV/Vis‐NIR Spectroelectrochemical Investigation of a Persistent Phosphanyl Radical Dication

The reaction of the bis(imidazoliumyl)‐substituted P I  cation [(2‐Im Dipp )P(4‐Im Dipp )] + ( 10 + ) (2‐Im=imidazolium‐2‐yl; 4‐Im=imidazolium‐4‐yl; Dipp=2,6‐di‐isopropylphenyl) with trifluoromethanesulfonic acid (HOTf) or methyl trifluoromethylsulfonate (MeOTf) yields the corresponding protonated [(2‐Im Dipp )PH(4‐Im Dipp )] 2+ ( 11 2+ ) and methylated [(2‐Im Dipp )PMe(4‐Im Dipp )] 2+ ( 12 2+ ) dications, respectively. EPR/UV/Vis‐NIR spectroelectrochemical investigation of the low‐coordinated P I  cation 10 + predicted a stable and “bottleable” P‐centered radical dication [(2‐Im Dipp )P(4‐Im Dipp )] 2+. ( 13 2+. ). The reaction of 10 + with the nitrosyl salt NO[OTf] yields the persistent phosphanyl radical dication 13 2+. as triflate salt in crystalline form. Quantum chemical investigation revealed an exceptional high spin density at the P atom.