Editing Curium (section)

==Compounds and reactions==
{{Main|Curium compounds}}

===Oxides===
Curium readily reacts with oxygen forming mostly Cm<sub>2</sub>O<sub>3</sub> and CmO<sub>2</sub> oxides,<ref name="lenntech" /> but the divalent oxide CmO is also known.<ref name="HOWI_1972">Holleman, p. 1972</ref> Black CmO<sub>2</sub> can be obtained by burning curium [[oxalate]] ({{chem|Cm|2|(C|2|O|4|)|3}}), nitrate ({{chem|Cm|(N|O|3|)|3}}), or hydroxide in pure oxygen.<ref name="asprey" /><ref name="g1268">Greenwood, p. 1268</ref> Upon heating to 600–650&nbsp;°C in vacuum (about 0.01&nbsp;[[Pascal (unit)|Pa]]), it transforms into the whitish Cm<sub>2</sub>O<sub>3</sub>:<ref name="asprey">{{cite journal|last1=Asprey|first1=L. B.|title=Evidence for Quadrivalent Curium: X-Ray Data on Curium Oxides1|last2=Ellinger|first2=F. H.|last3=Fried|first3=S.|last4=Zachariasen|first4=W. H.|journal=Journal of the American Chemical Society|volume=77|issue=6|page=1707|date=1955|doi=10.1021/ja01611a108|bibcode=1955JAChS..77.1707A }}</ref><ref>{{cite journal|last1=Noe|first1=M.|title=Self-radiation effects on the lattice parameter of 244CmO2|journal=Inorganic and Nuclear Chemistry Letters|volume=7|issue=5|page=421|date=1971|doi=10.1016/0020-1650(71)80177-0|last2=Fuger|first2=J.}}</ref>
: <chem>4CmO2 ->[\Delta T] 2Cm2O3 + O2</chem>.

Or, Cm<sub>2</sub>O<sub>3</sub> can be obtained by reducing CmO<sub>2</sub> with molecular [[hydrogen]]:<ref>{{cite journal|last1=Haug|first1=H.|title=Curium sesquioxide Cm2O3|journal=Journal of Inorganic and Nuclear Chemistry|volume=29|issue=11|page=2753|date=1967|doi=10.1016/0022-1902(67)80014-9}}</ref>
: <chem>2CmO2 + H2 -> Cm2O3 + H2O</chem>

Also, a number of ternary oxides of the type M(II)CmO<sub>3</sub> are known, where M stands for a divalent metal, such as barium.<ref>{{cite journal|last1=Fuger|first1=J.|last2=Haire|first2=R.|last3=Peterson|first3=J.|title=Molar enthalpies of formation of BaCmO3 and BaCfO3|journal=Journal of Alloys and Compounds|volume=200|issue=1–2|page=181|date=1993|doi=10.1016/0925-8388(93)90491-5|url=https://zenodo.org/record/1258637}}</ref>

Thermal oxidation of trace quantities of curium hydride (CmH<sub>2–3</sub>) has been reported to give a volatile form of CmO<sub>2</sub> and the volatile trioxide CmO<sub>3</sub>, one of two known examples of the very rare +6 state for curium.<ref name="CmO3" /> Another observed species was reported to behave similar to a supposed plutonium tetroxide and was tentatively characterized as CmO<sub>4</sub>, with curium in the extremely rare +8 state;<ref name="CmO4">{{cite journal |last1=Domanov |first1=V. P. |date=January 2013 |title=Possibility of generation of octavalent curium in the gas phase in the form of volatile tetraoxide CmO<sub>4</sub> |journal=Radiochemistry |volume=55 |issue=1 |pages=46–51 |doi=10.1134/S1066362213010098 |bibcode=2013Radch..55...46D |s2cid=98076989 }}</ref> but new experiments seem to indicate that CmO<sub>4</sub> does not exist, and have cast doubt on the existence of PuO<sub>4</sub> as well.<ref>{{cite journal|last1=Zaitsevskii|first1=Andréi|last2=Schwarz|first2=W. H. Eugen|date=April 2014|title=Structures and stability of AnO4 isomers, An = Pu, Am, and Cm: a relativistic density functional study.|journal=Physical Chemistry Chemical Physics|volume=2014|issue=16|pages=8997–9001|bibcode=2014PCCP...16.8997Z|doi=10.1039/c4cp00235k|pmid=24695756}}<!--|access-date=March 8, 2015--></ref>

===Halides===
The colorless curium(III) fluoride (CmF<sub>3</sub>) can be made by adding fluoride ions into curium(III)-containing solutions. The brown tetravalent curium(IV) fluoride (CmF<sub>4</sub>) on the other hand is only obtained by reacting curium(III) fluoride with molecular [[fluorine]]:<ref name = "Morrs" />
: <math>\mathrm{2\ CmF_3\ +\ F_2\ \longrightarrow\ 2\ CmF_4}</math>

A series of ternary fluorides are known of the form A<sub>7</sub>Cm<sub>6</sub>F<sub>31</sub> (A = [[alkali metal]]).<ref>{{cite journal|last1=Keenan|first1=T.|title=Lattice constants of K7Cm6F31 trends in the 1:1 and 7:6 alkali metal-actinide(IV) series|journal=Inorganic and Nuclear Chemistry Letters|volume=3|issue=10|page=391|date=1967|doi=10.1016/0020-1650(67)80092-8}}</ref>

The colorless [[curium(III) chloride]] (CmCl<sub>3</sub>) is made by reacting [[curium hydroxide]] (Cm(OH)<sub>3</sub>) with anhydrous [[hydrogen chloride]] gas. It can be further turned into other halides such as curium(III) bromide (colorless to light green) and [[curium(III) iodide]] (colorless), by reacting it with the [[ammonia]] salt of the corresponding halide at temperatures of ~400–450&nbsp;°C:<ref>{{cite journal|title=Crystal Structures of the Trifluorides, Trichlorides, Tribromides, and Triiodides of Americium and Curium|last1=Asprey|first1=L. B.|last2=Keenan|first2=T. K.|last3=Kruse|first3=F. H.|journal=Inorganic Chemistry|volume=4|issue=7|page=985|date=1965|doi=10.1021/ic50029a013|s2cid=96551460 |url=https://digital.library.unt.edu/ark:/67531/metadc1035960/}}</ref>
: <math>\mathrm{CmCl_3\ +\ 3\ NH_4I\ \longrightarrow \ CmI_3\ +\ 3\ NH_4Cl}</math>

Or, one can heat curium oxide to ~600°C with the corresponding acid (such as [[hydrobromic acid|hydrobromic]] for curium bromide).<ref>{{cite journal|last1=Burns|first1=J.|title=Crystallographic studies of some transuranic trihalides: 239PuCl3, 244CmBr3, 249BkBr3 and 249CfBr3|journal=Journal of Inorganic and Nuclear Chemistry|volume=37|issue=3|page=743|date=1975|doi=10.1016/0022-1902(75)80532-X|last2=Peterson|first2=J. R.|last3=Stevenson|first3=J. N.}}</ref><ref>{{cite journal|last1=Wallmann|first1=J.|title=Crystal structure and lattice parameters of curium trichloride|journal=Journal of Inorganic and Nuclear Chemistry|volume=29|issue=11|page=2745|date=1967|doi=10.1016/0022-1902(67)80013-7|last2=Fuger|first2=J.|last3=Peterson|first3=J. R.|last4=Green|first4=J. L.|s2cid=97334114 }}</ref> Vapor phase [[hydrolysis]] of curium(III) chloride gives curium oxychloride:<ref>{{cite journal|last1=Weigel|first1=F.|last2=Wishnevsky|first2=V.|last3=Hauske|first3=H.|title=The vapor phase hydrolysis of PuCl3 and CmCl3: heats of formation of PuOC1 and CmOCl|journal=Journal of the Less Common Metals|volume=56|issue=1|page=113|date=1977|doi=10.1016/0022-5088(77)90224-7}}</ref>
: <math>\mathrm{CmCl_3\ +\ \ H_2O\ \longrightarrow \ CmOCl\ +\ 2\ HCl}</math>

===Chalcogenides and pnictides===
Sulfides, selenides and tellurides of curium have been obtained by treating curium with gaseous [[sulfur]], [[selenium]] or [[tellurium]] in vacuum at elevated temperature.<ref>Troc, R. [https://books.google.com/books?id=vkzx_t3zLR0C&pg=PA4 Actinide Monochalcogenides, Volume 27], Springer, 2009 {{ISBN|3-540-29177-6}}, p. 4</ref><ref>{{cite journal|last1=Damien|first1=D.|title=Preparation and lattice parameters of curium sulfides and selenides|journal=Inorganic and Nuclear Chemistry Letters|volume=11|issue=7–8|page=451|date=1975|doi=10.1016/0020-1650(75)80017-1|last2=Charvillat|first2=J. P.|last3=Müller|first3=W.}}</ref> Curium [[pnictogen|pnictides]] of the type CmX are known for [[nitrogen]], [[phosphorus]], [[arsenic]] and [[antimony]].<ref name="Morrs" /> They can be prepared by reacting either curium(III) hydride (CmH<sub>3</sub>) or metallic curium with these elements at elevated temperature.<ref name="CuriumChap9">Lumetta, G. J.; Thompson, M. C.; Penneman, R. A.; Eller, P. G. [http://radchem.nevada.edu/classes/rdch710/files/curium.pdf Curium] {{webarchive|url=https://web.archive.org/web/20100717154205/http://radchem.nevada.edu/classes/rdch710/files/curium.pdf |date=2010-07-17 }}, Chapter Nine in ''Radioanalytical Chemistry'', Springer, 2004, pp. 1420–1421. {{ISBN|0387341226}}, {{ISBN|978-0387 341224}}</ref>

===Organocurium compounds and biological aspects===
[[File:Uranocene-3D-balls.png|thumb|upright=0.5|Predicted curocene structure]]
Organometallic complexes analogous to [[uranocene]] are known also for other actinides, such as thorium, protactinium, neptunium, plutonium and americium. [[Molecular orbital theory]] predicts a stable "curocene" complex (η<sup>8</sup>-C<sub>8</sub>H<sub>8</sub>)<sub>2</sub>Cm, but it has not been reported experimentally yet.<ref>Elschenbroich, Ch. Organometallic Chemistry, 6th edition, Wiesbaden 2008, {{ISBN|978-3-8351-0167-8}}, p. 589</ref><ref>{{cite journal|last1=Kerridge|first1=Andrew|last2=Kaltsoyannis|first2=Nikolas|title=Are the Ground States of the Later Actinocenes Multiconfigurational? All-Electron Spin−Orbit Coupled CASPT2 Calculations on An(η8-C8H8)2(An = Th, U, Pu, Cm)|journal=The Journal of Physical Chemistry A|volume=113|issue=30|date=2009|pmid=19719318|doi=10.1021/jp903912q|pages=8737–8745|bibcode=2009JPCA..113.8737K|url=https://figshare.com/articles/Are_the_Ground_States_of_the_Later_Actinocenes_Multiconfigurational_All_Electron_Spin_Orbit_Coupled_CASPT2_Calculations_on_An_sup_8_sup_C_sub_8_sub_H_sub_8_sub_sub_2_sub_An_Th_U_Pu_Cm_/2840251}}</ref>

Formation of the complexes of the type {{chem|Cm|(|n-C|3|H|7|-BTP)|3}} (BTP = 2,6-di(1,2,4-triazin-3-yl)pyridine), in solutions containing n-C<sub>3</sub>H<sub>7</sub>-BTP and Cm<sup>3+</sup> ions has been confirmed by [[Extended X-ray absorption fine structure|EXAFS]]. Some of these BTP-type complexes selectively interact with curium and thus are useful for separating it from lanthanides and another actinides.<ref name="denecke" /><ref>{{cite journal|last1=Girnt|first1=Denise|last2=Roesky|first2=Peter W.|last3=Geist|first3=Andreas|last4=Ruff|first4=Christian M.|last5=Panak|first5=Petra J.|last6=Denecke|first6=Melissa A.|s2cid=978265|title=6-(3,5-Dimethyl-1H-pyrazol-1-yl)-2,2′-bipyridine as Ligand for Actinide(III)/Lanthanide(III) Separation|journal=Inorganic Chemistry|volume=49|issue=20|date=2010|pmid=20849125|doi=10.1021/ic101309j|pages=9627–9635}}</ref> Dissolved Cm<sup>3+</sup> ions bind with many organic compounds, such as [[hydroxamic acid]],<ref name="pl1">{{cite journal|last1=Glorius|first1=M.|last2=Moll|first2=H.|last3=Bernhard|first3=G.|title=Complexation of curium(III) with hydroxamic acids investigated by time-resolved laser-induced fluorescence spectroscopy|journal=Polyhedron|volume=27|issue=9–10|page=2113|date=2008|doi=10.1016/j.poly.2008.04.002}}</ref> [[urea]],<ref name="pl2">{{cite journal|last1=Heller|first1=Anne|last2=Barkleit|first2=Astrid|last3=Bernhard|first3=Gert|last4=Ackermann|first4=Jörg-Uwe|title=Complexation study of europium(III) and curium(III) with urea in aqueous solution investigated by time-resolved laser-induced fluorescence spectroscopy|journal=Inorganica Chimica Acta|volume=362|issue=4|page=1215|date=2009|doi=10.1016/j.ica.2008.06.016}}</ref> [[fluorescein]]<ref name="pl3">{{cite journal|last1=Moll|first1=Henry|last2=Johnsson|first2=Anna|last3=Schäfer|first3=Mathias|last4=Pedersen|first4=Karsten|last5=Budzikiewicz|first5=Herbert|last6=Bernhard|first6=Gert|title=Curium(III) complexation with pyoverdins secreted by a groundwater strain of Pseudomonas fluorescens|journal=BioMetals|volume=21|issue=2|date=2007|pmid=17653625|doi=10.1007/s10534-007-9111-x|pages=219–228|s2cid=24565144}}</ref> and [[adenosine triphosphate]].<ref name="pl4">{{cite journal|last1=Moll|first1=Henry|last2=Geipel|first2=Gerhard|last3=Bernhard|first3=Gert|title=Complexation of curium(III) by adenosine 5′-triphosphate (ATP): A time-resolved laser-induced fluorescence spectroscopy (TRLFS) study|journal=Inorganica Chimica Acta|volume=358|issue=7|page=2275|date=2005|doi=10.1016/j.ica.2004.12.055}}</ref> Many of these compounds are related to biological activity of various [[microorganism]]s. The resulting complexes show strong yellow-orange emission under UV light excitation, which is convenient not only for their detection, but also for studying interactions between the Cm<sup>3+</sup> ion and the ligands via changes in the half-life (of the order ~0.1 ms) and spectrum of the fluorescence.<ref name="plb" /><ref name="pl1" /><ref name="pl2" /><ref name="pl3" /><ref name="pl4" />

There are a few reports on [[biosorption]] of Cm<sup>3+</sup> by [[bacteria]] and [[archaea]],<ref>{{cite journal|doi=10.1021/es0301166|last1=Moll|first1=H.|last2=Stumpf|first2=T.|last3=Merroun|first3=M.|last4=Rossberg|first4=A.|last5=Selenska-Pobell|first5=S.|last6=Bernhard|first6=G.|title=Time-resolved laser fluorescence spectroscopy study on the interaction of curium(III) with Desulfovibrio äspöensis DSM 10631T|journal=Environmental Science & Technology|volume=38|issue=5|pages=1455–1459|date=2004|pmid=15046347|bibcode = 2004EnST...38.1455M }}</ref><ref>{{cite journal|author=Ozaki, T.|display-authors=etal|url=http://sciencelinks.jp/j-east/article/200305/000020030503A0110480.php|archive-url=https://web.archive.org/web/20090225195752/http://sciencelinks.jp/j-east/article/200305/000020030503A0110480.php|url-status=dead|archive-date=2009-02-25|title=Association of Eu(III) and Cm(III) with Bacillus subtilis and Halobacterium salinarium|journal=Journal of Nuclear Science and Technology|date=2002|volume=Suppl. 3|pages=950–953|doi=10.1080/00223131.2002.10875626|bibcode=2002JNST...39S.950O |s2cid=98319565}}</ref> and in the laboratory both americium and curium were found to support the growth of [[methylotroph]]s.<ref>{{cite journal |last1=Remick |first1=Kaleigh |last2=Helmann |first2=John D. |title=The Elements of Life: A Biocentric Tour of the Periodic Table |journal=Advances in Microbial Physiology |publisher=PubMed Central |date=30 January 2023 |volume=82 |pages=1–127 |doi=10.1016/bs.ampbs.2022.11.001 |pmid=36948652 |pmc=10727122 |isbn=978-0-443-19334-7}}</ref>