Cyclic Distiba- and Dibisihadiazenium Cations

摘要

Four-membered pnictogen-nitrogen heterocycles of the type [XE(μ-NR)]2 (E = element of Group 15, X = halogen) are known as 1,3-dihalogeno-cyclo-1,3-dipnicta(III)-2,4-diazanes (Scheme 1, species A). The phosphorus species in particular play a major role in preparative phosphorus-nitrogen chemistry, for example in the preparation of macrocycles, polymers, main-group complexes, and ring transformation reactions or the generation of cyclic binary PN cations.In recent years, new examples for cyclo-1,3-dipnicta(III)-2,4-diazanes were prepared by introduction of bulky R substituents and characterized, with the focus on kinetic stabilization. Only recently, the synthesis of salts bearing the highly reactive cyclo -1,3-dipnicta(III)-2,4-diazenium cations [ClE-(μ-NTer)2E]~+ (E = P and As; Ter = terphenyl = 2,6-bis(2,4,6-trimethylphenyl)phenyl; Scheme 1, species B) was reported. The generation of such cations was achieved by halide abstraction upon addition of strong Lewis acids, such as GaCl3. Utilization of the bulky terphenyl group leads to the formation of separated ion pairs in the crystal with large interionic distances.