Technetium(VII) oxide

{{chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 407107879

| ImageFile = Tc2O7.png

| ImageSize =

| ImageCaption = Structural formula of technetium(VII) oxide.

| ImageFile1 = Technetium(VII)-oxid.png

| ImageFileL1 = Technetium(VII)-oxide-from-xtal-3D-SF.png

| ImageFileR1 = Technetium(VII)-oxide-from-xtal-3D-balls.png

| ImageSize1 = 240px

| ImageAlt1 = Unit cell of technetium(VII) oxide under standard conditions.

| ImageCaption1 = Unit cell of technetium(VII) oxide.

| IUPACName = Technetium(VII) oxide

| OtherNames = Technetium heptoxide

| Section1 = {{Chembox Identifiers

| CASNo_Ref = {{cascite|changed|??}}

| CASNo = 12165-21-8

| PubChem = 22227441

| InChI = 1S/7O.2Tc/q7*-2;2*+7

| SMILES = O=[Tc](=O)(=O)O[Tc](=O)(=O)=O

}}

| Section2 = {{Chembox Properties

| Formula = Tc₂O₇

| MolarMass = 307.810 g/mol

| Appearance = light yellow solid

| Density = 3.5 g/cm³

| MeltingPtC = 119.5

| BoilingPtC = 310.6

| Solubility = hydrolysis to HTcO₄

| MagSus = −40.0·10⁻⁶ cm³/mol

}}

| Section3 = {{Chembox Structure

| Structure_ref =

| CrystalStruct = Primitive orthorhombic

| LattConst_a = 1375.6 pm

| LattConst_b = 743.9 pm

| LattConst_c = 561.7 pm

| LattConst_ref = {{cite journal|last=Krebs|first=Bernt|title=Technetium(VII)-oxid: Ein Übergangsmetalloxid mit Molekülstruktur im festen Zustand|journal=Zeitschrift für anorganische und allgemeine Chemie|volume=380|year=1971|issue=2|pages=146–159|doi=10.1002/zaac.19713800205}}

| SpaceGroup = Pbca, No. 61

}}

| Section7 = {{Chembox Hazards

| MainHazards = radioactive

| FlashPt =

| AutoignitionPt =

}}

}}

File:Technetium-99 oxide.png|Technetium (VII) oxide containing Technetium-99]]

Technetium(VII) oxide is the chemical compound with the formula Tc₂O₇. This yellow volatile solid is a rare example of a molecular binary metal oxide, the other examples being RuO₄, OsO₄, and the unstable Mn₂O₇. It adopts a centrosymmetric corner-shared bi-tetrahedral structure in which the terminal and bridging Tc−O bonds are 167pm and 184 pm respectively and the Tc−O−Tc angle is 180°.{{cite journal|last=Krebs|first=Bernt|title = Technetium(VII)-oxid: Ein Übergangsmetalloxid mit Molekülstruktur im festen Zustand| journal = Angewandte Chemie | year = 1969 | volume = 81| issue = 9| pages = 328–329| doi = 10.1002/ange.19690810905|bibcode=1969AngCh..81..328K}}

Technetium(VII) oxide is prepared by the oxidation of technetium at 450–500 °C:{{cite book|author1=Herrell, A. Y. |author2=Busey, R. H. |author3=Gayer, K. H. | title = Technetium(VII) Oxide, in Inorganic Syntheses| year = 1977 | volume = XVII| pages = 155–158 | isbn = 0-07-044327-0|doi=10.1002/9780470132487.ch41}}

:4 Tc + 7 O₂ → 2 Tc₂O₇

It is the anhydride of pertechnetic acid and the precursor to sodium pertechnetate:

:Tc₂O₇ + 2 H₂O → 2 HTcO₄

:Tc₂O₇ + 2 NaOH → 2 NaTcO₄ + H₂O