Reactions of R 3 PNNPR 3 Species with Boranes: Classical Adducts, FLPs, and Radical Cations

Abstract Although the nature of bis ‐phosphazine species is of much interest, there are few reports of their reactivity. Herein, we show that the bis ‐phosphazine species Ph 3 PNNPPh 3 1 react with Lewis acids to give the Lewis acid adducts Ph 3 PNN(B(C 6 F 5 ) 3 )PPh 3 3 and Ph 3 PN(BF 3 )N(BF 3 )PPh 3 4 . Compound 1 also generates a frustrated Lewis pair (FLP) in the presence of BPh 3 and thermolysis of 1 /BPh 3 , or 3 at 80 °C released N 2 while 4 was stable at 80 °C. In contrast, the species Cy 3 PNNPCy 3 2 reacted with B(C 6 F 5 ) 3 to effect single electron transfer affording a frustrated radical pair (FRP). Independent reactions of 1 and 2 with [Cp 2 Fe][BF 4 ] gave the corresponding radical salts [R 3 PNNPR 3 ] •+ [BF 4 ] (R = Cy 5b Ph 6 ). Structural and computational data show the N─N bond is strengthened in the bis ‐phosphazine radical cation.