Kim C. Lobring

The thermochemistry of Group 15 tetrachloride anions

Bond strengths for a series of Group 15 tetrachloride anions AC14− (A = P, As, Sb, and Bi) have been determined by measuring thresholds for collision-induced dissociation of the anions in a flowing afterglow-tandem mass spectrometer. The central atoms in these systems have ten electrons, which violates the octet rule: the bond dissociation energies for ACl4− help to clarify the effect of the central atom on hypervalent bond strengths. The 0 K bond energies in kJ mol−1 are D(Cl3A-Cr−1) = 90 ± 7, 115 ± 7, 161 ± 8, and 154 ± 15, respectively. Computational results using the B3LYP/LANL2DZpd level of theory are higher than the experimental bond energies. Calculations give a geometry for BiCl4− that is essentially tetrahedral rather than the see-saw observed for the other tetrachlorides. NBO calculations predict that the phosphorus and arsenic systems have 3C-4E bonds, while the antimony and bismuth systems are more ionic.

Single crystal growth, bonding analysis and superconductivity of V2Ga5

Synthesis of the superconducting V2Ga5 compound was achieved using molten Ga as the flux material. Large single crystals of 30 mm in length can be obtained with this method. Single crystal X-ray diffraction and computational studies were carried out for this compound. V2Ga5 crystallizes in the tetragonal lattice P4/mbm (No. 127) with lattice constants a=8.936(3) A, c=2.683(2) A, V=214.3(2) A3, and Z=2. Computational study shows that bonding in this compound is delocalized, and the majority states at the Fermi level are the vanadium d-band. Resistivity and magnetization measurements have confirmed that the solid is a bulk type II superconductor with TC=3.59 K.