title: The thermochemistry of group 15 tetrachloride anions.
abstract: Bond strengths for a series of Group 15 tetrachloride anions ACl4 (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-CL-) = 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.
authors.affiliation: Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb 60115, USA.
authors.forename: Barry W
authors.initials: BW
authors.lastname: Walker
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Check
authors.forename: Kim C
authors.initials: KC
authors.lastname: Lobring
authors.forename: Cynthia Ann
authors.initials: CA
authors.lastname: Pommerening
authors.forename: Lee S
authors.initials: LS
authors.lastname: Sunderlin