Protactinium monoxide

{{Chembox

| IUPACName = Protactinium(II) oxide

| ImageFile =

| ImageName =

| Section1 = {{Chembox Identifiers

| SMILES = [O-2].[Pa+2]

| CASNo = 60936-60-9

| CASNo_Ref = {{cascite|correct|CAS}}

| StdInChI=1S/O.Pa/q-2;+2

| StdInChIKey=QQSJTSKFWWYZFZ-UHFFFAOYSA-N

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| Section2 = {{Chembox Properties

| Formula= PaO

| MolarMass = 247.035 g mol⁻¹

| Appearance = black crystals

| Density = 13.44 g/cm³

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| Section3 = {{Chembox Structure

| CrystalStruct = rocksalt{{cite journal|doi = 10.1021/ja01652a011|year = 1954|last1 = Sellers|first1 = Philip A.|last2 = Fried|first2 = Sherman|last3 = Elson|first3 = Robert E.|last4 = Zachariasen|first4 = W. H.|journal = Journal of the American Chemical Society|volume = 76|pages = 5935|title = The Preparation of Some Protactinium Compounds and the Metal|issue = 23| url=https://digital.library.unt.edu/ark:/67531/metadc172625/ |url-access = subscription}}

| SpaceGroup = Fm{{overline|3}}m, No. 225

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Protactinium monoxide is a radioactive inorganic compound and one of the oxides of protactinium. Its chemical formula is PaO. It is a black solid that crystallizes in the rock-salt structure. Protactinium monoxide can be produced in minute quantities from the oxidation of protactinium.

The protactinium monoxide cation (PaO+) is very active and can activate hydrocarbons such as alkenes.{{cite journal|journal=Physical Chemistry Chemical Physics|volume=13|issue=28|language=en|issn=1463-9076|date=2011|pages=12940–12958|doi=10.1039/c1cp20996e|url=http://xlink.rsc.org/?DOI=c1cp20996e|title=Actinide sulfides in the gas phase: experimental and theoretical studies of the thermochemistry of AnS (An = Ac, Th, Pa, U, Np, Pu, Am and Cm)|accessdate=2021-08-24|author=Cláudia C. L. Pereira, Colin J. Marsden, Joaquim Marçalo, John K. Gibson|pmid=21687883 |bibcode=2011PCCP...1312940P |url-access=subscription}}