Anion stabilised hypercloso-hexaalane Al6H6

Simon J Bonyhady,Gernot Frenking,Nicole Holzmann,Cameron Jones,David Collis,Ross O Piltz,Alison J Edwards,Andreas Stasch

doi:10.1038/s41467-018-05504-x

Abstract

Boron hydride clusters are an extremely diverse compound class, which are of enormous importance to many areas of chemistry. Despite this, stable aluminium hydride analogues of these species have remained staunchly elusive to synthetic chemists. Here, we report that reductions of an amidinato-aluminium(III) hydride complex with magnesium(I) dimers lead to unprecedented examples of stable aluminium(I) hydride complexes, [(ArNacnac)Mg]2[Al6H6(Fiso)2] (ArNacnac = [HC(MeCNAr)2]−, Ar = C6H2Me3-2,4,6 Mes; C6H3Et2-2,6 Dep or C6H3Me2-2,6 Xyl; Fiso = [HC(NDip)2]−, Dip = C6H3Pri2-2,6), which crystallographic and computational studies show to possess near neutral, octahedral hypercloso-hexaalane, Al6H6, cluster cores. The electronically delocalised skeletal bonding in these species is compared to that in the classical borane, [B6H6]2−. Thus, the chemistry of classical polyhedral boranes is extended to stable aluminium hydride clusters for the first time.

Highlights

Boron hydride clusters are an extremely diverse compound class, which are of enormous importance to many areas of chemistry
The vast majority of these species are low oxidation state boron cluster compounds, which exhibit an enormous array of structural types[1]
The understanding of the structures of such clusters required the early development of revolutionary theories on chemical bonding (e.g. Wade–Mingos rules for electron counting)[2,3], which led to boranes finding applications in areas as diverse as synthesis[4], rocket fuel technology[5] and medical science[6]

Summary

Introduction

Boron hydride clusters are an extremely diverse compound class, which are of enormous importance to many areas of chemistry. The cluster compounds have negligible solubility in common deuterated solvents once crystallised, so no meaningful solution state spectroscopic data could be acquired for them. 5–20%) of the deep red crystalline aluminium(I) hydride cluster compounds 1 (Fig. 1), upon cooling the reaction solutions to ambient temperature.

Results

Conclusion