A Stable Hexacoordinated Arsenic(V) Dication

Abstract

Polycations of main-group elements have emerged as a significant research focus in recent years. Hypercoordinated dications having heavier pnictogens, such as antimony (Sb) and bismuth (Bi), as a central atom have been extensively studied due to their large atomic radii. However, limited research has been conducted on the corresponding dications of lighter pnictogens such as phosphorus (P) and arsenic (As). In this study, we synthesized a 2-(2-pyridyl)phenyl (ppy)-ligated arsenic dication ([(ppy)₃As][SbCl₆]₂ and [(ppy)₃As]Cl₂) as a first example of novel hexacoordinated arsenic-centered dication species. This arsenic-centered dication species demonstrates remarkable stability at high temperatures and in hot water. Both experimental and computational analyses indicated that their exceptional stability is primarily due to strong As–N interactions. Notably, the arsenic-centered dication species exhibits greater stability than their antimony counterparts.