Synthesis, reactivity and structural studies of selenide bridged carboranyl compounds

Abstract

Reaction of the lithium salt Li[1-R-1,2-closo-C₂B₁₀H₁₀] with selenium under mild conditions, followed by hydrolysis gave the diselenide compound (1-Se-2-R-1,2-closo-C₂B₁₀H₁₀)₂ in contrast to the well-reported mercapto compounds 1-SH-2-R-1,2-closo-C₂B₁₀H₁₀ obtained using a similar synthetic procedure. Details for the preparation and X-ray structural characterisation of the new compounds (2-Me-1,2-closo-C₂B₁₀H₁₀)₂Se (1), (1-Se-2-R-1,2-closo-C₂B₁₀H₁₀)₂ (R = Me,2, Ph, 3) are specified. To further explore the mechanism of the dimerization reaction, the complex [Au(1-Se-2-Me-1,2-closo-C₂B₁₀H₁₀)(PPh₃)] 4 was synthesized, confirming the existence of the intermediate Li[1-Se-2-R-1,2-closo-C₂B₁₀H₁₀] at the early stages of the reaction before selenium oxidation. Theoretical calculations and cyclic voltammetry (CV) studies were carried out to compare the bonding nature of the sulfur and the selenium analog compounds. It was determined that diselenides have a higher tendency to reduce with respect to the disulfides and all chalcogen atoms were found to be positively charged.