Interconversion of Diborane (4) Isomers. (Reannouncement with New AvailabilityInformation)

摘要

Highly correlated electronic structure calculations using many-body perturbationtheory and coupled-cluster gradient techniques are applied to a study of a reaction pathway which links the two forms of diborane. A reaction coordinate which preserves (C sub 2) symmetry is studied, as this mechanism is allowed by orbital symmetry rules. However, calculations show that the minimum energy path does not conform to this idealized mechanism. Rather, the reaction coordinate bifurcates, and the transition state contains no nontrivial elements of symmetry. At the level of partial fourth-order many-body perturbation theory with a large triple-zeta plus double polarization basis set, differences in distances between the hydrogen atoms corresponding to the bridge atoms in the (C sub 2V) form and the two boron atoms are 0.14 and 0.81 A, reflecting the pronounced asymmetry of the transition state structure.