Search

Inverse carbon-free sandwich structures with formula E2P4 (E=Al, Ga, In, Tl) have been proposed as a promising new target in main-group chemistry. Our computational exploration of their corresponding potential-energy surfaces at the S12h/TZ2P level shows that indeed stable carbon-free inverse-sandwiches can be obtained if one chooses an appropriate Group 13 element for E. The boron analogue B2P4 does not form the D4 h-symmetric inverse-sandwich structure, but instead prefers a D2 d structure of two perpendicular BP2 units with the formation of a double BB bond. For the other elements of Group 13, Al-Tl, the most favorable isomer is the D4 h inverse-sandwich structure. The preference for the D2 d isomer for B2P4 and D4 h for their heavier analogues has been rationalized in terms of an isomerization-energy decomposition analysis, and further corroborated by determination of aromaticity of these species. [ABSTRACT FROM AUTHOR]