Electronic structures of the closo-thiaboranes 1-SB9H9 and 1-SB11H11. Electrophilic substitution in 1-SB9H2

Abstract

Comparison of the results of MNDO calculations for 1 -SB₉H₉ and the previously reported gas-phase photoelectron spectrum enables the cluster-bonding molecular orbitals to be assigned. The electronic structure of 1-SB₉H₉ is compared with those of [B₁₀H₁₀]^2–, 1,10-B₁₀H₈(N₂)₂′ and 1,10-C₂B₈H₁₀. The cluster bonding in these compounds is found to be very similar. The bonding in 1-SB₁₁H₁₁ is also analysed. Possible sites for the substitution of 1-SB₉H₉ by electrophiles X⁺(e.g. H⁺) are examined. The observed substitution patterns are rationalised on the basis of the calculated atomic charges and the composition of the highest filled molecular orbitals.