title: Pressure-induced formation of molecular B2X4(μ-X)2 (X = Cl, Br, I) species.
abstract: Boron(III) halides (BX(3), where X = F, Cl, Br, I) at ambient pressure conditions exist as strictly monomeric, trigonal-planar molecules. Using correlated ab initio calculations, the three heavier halides (X = Cl, Br, I) are shown to possess B(2)X(4)(μ-X)(2) local minima, isostructural with the diborane molecule. The calculated dissociation barrier of the B(2)I(4)(μ-I)(2) species [≈14 kJ/mol with CCSD(T)/cc-pVTZ] may be high enough to allow cryogenic isolation. The remaining dimer structures are more labile, with dissociation barriers of less than 6 kJ/mol. All three dimer species may be stabilized by application of external pressure. Periodic density functional theory calculations predict a new dimer-based P1 solid, which becomes more stable than the P6(3)/m monomer-derived solids at 5 (X = I) to 15 (X = Cl) GPa. Metadynamics simulations suggest that B(2)X(4)(μ-X)(2)-based solids are the kinetically preferred product of pressurization of the P6(3)/m solid.
authors.affiliation: Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Canada K1A 0R6.
authors.forename: Serguei
authors.initials: S
authors.lastname: Patchkovskii
authors.forename: Dennis D
authors.initials: DD
authors.lastname: Klug
authors.forename: Yansun
authors.initials: Y
authors.lastname: Yao