title: Synthetic and coordination chemistry of the heavier trivalent technetium binary halides: uncovering technetium triiodide.
abstract: Technetium tribromide and triiodide were obtained from the reaction of the quadruply Tc-Tc-bonded dimer Tc2(O2CCH3)4Cl2 with flowing HX(g) (X = Br, I) at elevated temperatures. At 150 and 300 °C, the reaction with HBr(g) yields TcBr3 crystallizing with the TiI3 structure type. The analogous reactions with flowing HI(g) yield TcI3, the first technetium binary iodide to be reported. Powder X-ray diffraction (PXRD) measurements show the compound to be amorphous at 150 °C and semicrystalline at 300 °C. X-ray absorption fine structure spectroscopy indicates TcI3 to consist of face-sharing TcI6 octahedra. Reactions of technetium metal with elemental iodine in a sealed Pyrex ampules in the temperature range 250-400 °C were performed. At 250 °C, no reaction occurred, while the reaction at 400 °C yielded a product whose PXRD pattern matches the one of TcI3 obtained from the reaction of Tc2(O2CCH3)4Cl2 and flowing HI(g). The thermal stability of TcBr3 and TcI3 was investigated in Pyrex and/or quartz ampules at 450 °C under vacuum. Technetium tribromide decomposes to Na{[Tc6Br12]2Br} in a Pyrex ampule and to technetium metal in a quartz ampule; technetium triiodide decomposes to technetium metal in a Pyrex ampule.
authors.affiliation: Department of Chemistry, University of Nevada-Las Vegas , Las Vegas, Nevada 89154, United States.
authors.forename: Erik V
authors.initials: EV
authors.lastname: Johnstone
authors.forename: Frederic
authors.initials: F
authors.lastname: Poineau
authors.forename: Jenna
authors.initials: J
authors.lastname: Starkey
authors.forename: Thomas
authors.initials: T
authors.lastname: Hartmann
authors.forename: Paul M
authors.initials: PM
authors.lastname: Forster
authors.forename: Longzhou
authors.initials: L
authors.lastname: Ma
authors.forename: Jeremy
authors.initials: J
authors.lastname: Hilgar
authors.forename: Efrain E
authors.initials: EE
authors.lastname: Rodriguez
authors.forename: Romina
authors.initials: R
authors.lastname: Farmand
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Czerwinski
authors.forename: Alfred P
authors.initials: AP
authors.lastname: Sattelberger