title: Ditechnetium Heptoxide Revisited: Solid-State, Gas-Phase, and Theoretical Studies.
abstract: Ditechnetium heptoxide was synthesized from the oxidation of TcO2with O2at 450 °C and characterized by single-crystal X-ray diffraction, electron-impact mass spectrometry (EI-MS), and theoretical methods. Refinement of the structure at 100 K indicates that Tc2O7crystallizes as a molecular solid in the orthorhombic space group Pbca [a = 7.312(3) Å, b = 5.562(2) Å, c = 13.707(5) Å, and V = 557.5(3) Å3]. The Tc2O7molecule can be described as corner-sharing TcO4tetrahedron [Tc---Tc = 3.698(1) Å and Tc-OBri-Tc = 180.0°]. The EI-MS spectrum of Tc2O7consists of both mononuclear and dinuclear species. The main dinuclear species in the gas-phase are Tc2O7(100%) and Tc2O5(56%), while the main mononuclear species are TcO3(33.9%) and TcO2(42.8%). The difference in the relative intensities of the M2O5(M = Tc, Re) fragments (1.7% for Re) indicates that these group 7 elements exhibit different gas-phase chemistry. The solid-state structure of Tc2O7was investigated by density functional theory methods. The optimized structure of the Tc2O7molecule is in good agreement with the experimental one. Simulations indicate that the more favorable geometry for the Tc2O7molecule in the gas-phase is bent (Tc-OBri-Tc = 156.5°), while a linear geometry (Tc-OBri-Tc = 180.0°) is favored in the solid-state.
authors.forename: Bradley C
authors.initials: BC
authors.lastname: Childs
authors.affiliation: Department of Chemistry, University of Zürich , Winterthurerstrasse 190, Zürich CH-8057, Switzerland.
authors.forename: Henrik
authors.initials: H
authors.lastname: Braband
authors.forename: Keith
authors.initials: K
authors.lastname: Lawler
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Mast
authors.affiliation: Department of Chemistry, University of Zürich , Winterthurerstrasse 190, Zürich CH-8057, Switzerland.
authors.forename: Laurent
authors.initials: L
authors.lastname: Bigler
authors.affiliation: Department of Chemistry, University of Zürich , Winterthurerstrasse 190, Zürich CH-8057, Switzerland.
authors.forename: Urs
authors.initials: U
authors.lastname: Stalder
authors.forename: Paul M
authors.initials: PM
authors.lastname: Forster
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Czerwinski
authors.affiliation: Department of Chemistry, University of Zürich , Winterthurerstrasse 190, Zürich CH-8057, Switzerland.
authors.forename: Roger
authors.initials: R
authors.lastname: Alberto
authors.affiliation: Office of the Director, Argonne National Laboratory (ANL) , Lemont, Illinois 60439, United States.
authors.forename: Alfred P
authors.initials: AP
authors.lastname: Sattelberger
authors.forename: Frederic
authors.initials: F
authors.lastname: Poineau