Icosahedral Meta-Carboranes Containing Exopolyhedral B-Se and B-Te Bonds

17 September 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Chalcogen-containing carboranes have been known for several decades and possess stable exopolyhedral B(9)-Se and B(9)-Te σ bonds despite the electron-donating ability of the B(9) vertex. While these molecules are known, little has been done to thoroughly evaluate their electrophilic and nucleophilic behavior. Herein, we report an assessment of the electrophilic reactivity of meta-carboranyl selenyl (II), tellurenyl (II), and tellurenyl (IV) chlorides and establish their reactivity pattern with Grignard reagents, alkenes, alkynes, enolates, and electron-rich arenes. These electrophilic reactions afford unique electron-rich B-Y-C (Y = Se, Te) bonding motifs not commonly found before. Furthermore, we show that meta-carboranyl selenolate, and even meta-carboranyl tellurolate, can be competent nucleophiles and participate in nucleophilic aromatic substitution reactions. Arene substitution chemistry is shown to be further extended to electron-rich species via the palladium mediated cross-coupling chemistry.

Keywords

carborane
boron cluster
chalcogen
organoselenium
organotellurium

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