The reactions of arachno-[B 9H 14] − and nido-[B 9H 12] − with acids: Preparation and structures of chlorononaborates

Abstract

Previous studies directed at cluster expansion via hydride abstraction reactions have produced a number of known neutral boranes, as well as unidentified products that account for up to half of the total boron content of the system. These unidentified products were previously suggested to be polymeric in nature. The unidentified product from the hydride abstraction reaction between [B 9H 14] − and BCl 3 that produces B 10H 14, [HBCl 3] −, and H 2 has been shown to consist of a mixture of singly-, doubly- and triply-chlorinated analogues of arachno-[B 9H 14] −. X-ray diffraction analyses indicate that these species co-crystallize in the solid state, and show a range of composition between 1.5 to approximately 3 Cl atoms per anion. Chlorine substitution occurs at adjacent positions of the B 9 framework. These problems of disorder prompted us to prepare an analogous singly-substituted cluster, [B 9H 13Cl] −. This species was obtained pure and in essentially quantitative yield from the reaction between nido-[B 9H 12] − and anhydrous HCl, and its structure was also determined by X-ray analysis.