title: Thorium and Uranium Hydride Phosphorus and Arsenic Bearing Molecules with Single and Double Actinide-Pnictogen and Bridged Agostic Hydrogen Bonds.
abstract: Thorium atoms from laser ablation react with phosphine during condensation in excess argon to produce two new infrared absorptions at 1467.2 and 1436.6 cm-1near weak bands for ThH and ThH2, which increase on annealing to 25 and 30 K, indicating spontaneous reactions. Analogous experiments with uranium produced two similar bands at 1473.4 and 1456.7 cm-1above UH at 1423.8 cm-1and another absorption at 1388.2 cm-1. Electronic structure calculations at the coupled cluster CCSD(T) for Th and density functional theory calculations for U as well as their proximity to other actinide hydride absorptions support assignments of these bands to the simplest molecules HP═ThH2, HP═UH2, and PH2-UH. Arsine gave the analogous products HAs═ThH2, HAs═UH2, and AsH2-UH. The HE═AnH2molecules (E = P, As; An = Th, U) have strong agostic An-H(E) interactions with H-E-An angles in the range of 60-64°. The calculated agostic bond distances are 9% to 12% longer than terminal single An-H bonds, which suggests that these strong agostic bonds can be considered as bridge bonds since similar relationships are found for the dibridged M2H6molecules (M = Al, Ga, In). The NBO analysis and the molecular orbitals show the presence of a σ and a π bond for HE═AnH2molecules that are heavily polarized with most of the density on the P or As.
authors.affiliation: Department of Chemistry, University of Virginia , P.O. Box 400319, Charlottesville, Virginia 22904-4319, United States.
authors.forename: Lester
authors.initials: L
authors.lastname: Andrews
authors.affiliation: Department of Chemistry, University of Virginia , P.O. Box 400319, Charlottesville, Virginia 22904-4319, United States.|Department of Chemistry, Incheon National University , 119 Academy-ro, Yeonsu-gu, Incheon 406-772, South Korea.
authors.forename: Han-Gook
authors.initials: HG
authors.lastname: Cho
authors.affiliation: Department of Chemistry, The University of Alabama , Tuscaloosa, Alabama 35487-0366, United States.
authors.forename: K Sahan
authors.initials: KS
authors.lastname: Thanthiriwatte
authors.affiliation: Department of Chemistry, The University of Alabama , Tuscaloosa, Alabama 35487-0366, United States.
authors.forename: David A
authors.identifier: http://orcid.org/0000-0002-9492-0056
authors.initials: DA
authors.lastname: Dixon