Substituent effects on the [1-closo-CB9H10]− anion geometry: experimental and DFT studies

Abstract

Five new structures of the [closo-1-CB₉H₁₀]⁻ anion substituted at the apical position(s) are reported expanding the pool of such derivatives to a total of 35. Geometrical features of twenty four of these experimental structures are compared to those obtained by full geometry optimization at the B3LYP/Def2TZVP level of theory. The range of derivatives permitted analysis of the substituent effect on the {closo-1-CB₉} cluster geometry as a function of Hammett parameters σ_p, which revealed a substantial impact of the B(10) substituent and negligible effect of the C(1) group. This structural report and analysis are accompanied by an overview of the progress in the development of functional derivatives of the [closo-1-CB₉H₁₀]⁻ anion and methods of their preparation.