Theoretical study of H2 elimination from [B n H n+1]- monoanions (n=6-9, 11)

Transition states of elementary reactions of H-2 molecule elimination from [B (n) H (n + 1)](-) anions (n = 6-9, 11) in which nucleophilic/electrophilic vacancies form at boron atoms have been localized by the density functional theory method (in the B3LYP/6-311++G** approximation). For a series of [B (n) H (n + 1)](-) anions (n = 6-12), the activation barriers to H2 elimination have been compared to consider the possibility of substitution for exopolyhedral hydrogen atoms by the mechanism with the first rate-limiting stage of formation of [B (n) H (n - 1)](-) (n = 6-12) intermediates with a vacant bare vertex of the boron cluster. For the [B (n) H (n) ](2-), [B (n) H (n + 1)](-), and [B (n) H (n - 1)](-) anions (n = 6-12), the electronic chemical potential mu and Pearson hardness eta have been evaluated since these characteristics make it possible to assess the propensity of different reagents to react with each other in terms of the empirical HSAB principle (soft with soft and hard with hard). The application of this principle is exemplified by the interaction of the [B10H9](-) and [B12H11](-) anions with acetonitrile CH3CN, furan C4H4O, and 18-crown-6.