Systematically Convergent Correlation Consistent Basis Sets for Molecular Core−Valence Correlation Effects: The Third-Row Atoms Gallium through Krypton

On the molecular and electronic structures of AsP3 and P4

The molecular and electronic structures of AsP(3) and P(4) have been investigated. Gas-phase electron diffraction studies of AsP(3) have provided r(g) bond lengths of 2.3041(12) and 2.1949(28) A for the As-P interatomic distances and the P-P interatomic distances, respectively. The gas-phase electron diffraction structure of P(4) has been redetermined and provides an updated value of 2.1994(3) A for the P-P interatomic distances, reconciling conflicting literature values. Gas-phase photoelectron spectroscopy provides experimental values for the energies of ionizations from the valence molecular orbitals of AsP(3) and P(4) and shows that electronically AsP(3) and P(4) are quite similar. Solid-state (75)As and (31)P NMR spectroscopy demonstrate the plastic nature of AsP(3) and P(4) as solids, and an extreme upfield (75)As chemical shift has been confirmed for the As atom in AsP(3). Finally, quantum chemical gauge-including magnetically induced current calculations show that AsP(3) and P(4) can accurately be described as strongly aromatic. Together these data provide a cohesive description of the molecular and electronic properties of these two tetraatomic molecules.

Heats of formation of XeF(3)(+), XeF(3)(-), XeF(5)(+), XeF(7)(+), XeF(7)(-), and XeF(8) from high level electronic structure calculations

Atomization energies at 0 K and heats of formation at 0 and 298 K are predicted for XeF(3)(+), XeF(3)(-), XeF(5)(+), XeF(7)(+), XeF(7)(-), and XeF(8) from coupled cluster theory (CCSD(T)) calculations with effective core potential correlation-consistent basis sets for Xe and including correlation of the nearest core electrons. Additional corrections are included to achieve near chemical accuracy of +/-1 kcal/mol. Vibrational zero point energies were computed at the MP2 level of theory. Unlike the other neutral xenon fluorides, XeF(8) is predicted to be thermodynamically unstable with respect to loss of F(2) with the reaction calculated to be exothermic by 22.3 kcal/mol at 0 K. XeF(7)(+) is also predicted to be thermodynamically unstable with respect to the loss of F(2) by 24.1 kcal/mol at 0 K. For XeF(3)(+), XeF(5)(+), XeF(3)(-), XeF(5)(-), and XeF(7)(-), the reactions for loss of F(2) are endothermic by 14.8, 37.8, 38.2, 59.6, and 31.9 kcal/mol at 0 K, respectively. The F(+) affinities of Xe, XeF(2), XeF(4), and XeF(6) are predicted to be 165.1, 155.3, 172.7, and 132.5 kcal/mol, and the corresponding F(-) affinities are 6.3, 19.9, 59.1, and 75.0 kcal/mol at 0 K, respectively.