title: Synthesis and structure of (Ph4P)2MCl6 (M = Ti, Zr, Hf, Th, U, Np, Pu).
abstract: High-purity syntheses are reported for a series of first, second, and third row transition metal and actinide hexahalide compounds with equivalent, noncoordinating countercations: (Ph(4)P)(2)TiF(6) (1) and (Ph(4)P)(2)MCl(6) (M = Ti, Zr, Hf, Th, U, Np, Pu; 2-8). While a reaction between MCl(4) (M = Zr, Hf, U) and 2 equiv of Ph(4)PCl provided 3, 4, and 6, syntheses for 1, 2, 5, 7, and 8 required multistep procedures. For example, a cation exchange reaction with Ph(4)PCl and (NH(4))(2)TiF(6) produced 1, which was used in a subsequent anion exchange reaction with Me(3)SiCl to synthesize 2. For 5, 7, and 8, synthetic routes starting with aqueous actinide precursors were developed that circumvented any need for anhydrous Th, Np, or Pu starting materials. The solid-state geometries, bond distances and angles for isolated ThCl(6)(2-), NpCl(6)(2-), and PuCl(6)(2-) anions with noncoordinating counter cations were determined for the first time in the X-ray crystal structures of 5, 7, and 8. Solution phase and solid-state diffuse reflectance spectra were also used to characterize 7 and 8. Transition metal MCl(6)(2-) anions showed the anticipated increase in M-Cl bond distances when changing from M = Ti to Zr, and then a decrease from Zr to Hf. The M-Cl bond distances also decreased from M = Th to U, Np, and Pu. Ionic radii can be used to predict average M-Cl bond distances with reasonable accuracy, which supports a principally ionic model of bonding for each of the (Ph(4)P)(2)MCl(6) complexes.
authors.affiliation: Inorganic, Isotope and Actinide Chemistry Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Stefan G
authors.initials: SG
authors.lastname: Minasian
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Boland
authors.forename: Russell K
authors.initials: RK
authors.lastname: Feller
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Gaunt
authors.forename: Stosh A
authors.initials: SA
authors.lastname: Kozimor
authors.forename: Iain
authors.initials: I
authors.lastname: May
authors.forename: Sean D
authors.initials: SD
authors.lastname: Reilly
authors.forename: Brian L
authors.initials: BL
authors.lastname: Scott
authors.forename: David K
authors.initials: DK
authors.lastname: Shuh