Chemical and electrochemical substitution of monocarbon carboranes; rationalisation of experimental behaviour of derivatives of [nido-7-CB10H13]– and [closo-1-CB11H12]–

Abstract

Controlled substitution of the monocarboranes [nido-7-CB₁₀H₁₃]^–, nido-7-Me₃N-7-CB₁₀H₁₂, and closo-1 -Me₃N-1-CB₁₁H₁₁has been achieved by chemical and electrochemical means. The position of boron substitution in 7-Me₃N-7-CB₁₀H₁₂derivatives depends on the experimental method. Chloride substitution at B(4) was achieved by electrophilic (electrochemical) methods, whereas HCl–AlCl₃resulted in substitution at B(9). Substitution at B(8) was obtained through a nido-closo-nido sequence of oxidation and ligand addition. The compounds were structurally characterised by ¹¹B–¹¹B correlation n.m.r. spectroscopy. The experimental data were correlated with AM1 calculations.