Editing Beryllium (section)

==Chemical properties==
{{Category see also|Beryllium compounds}}
A beryllium atom has the electronic configuration [He] 2s<sup>2</sup>. The predominant [[oxidation state]] of beryllium is +2; the beryllium atom has lost both of its valence electrons. Lower oxidation states complexes of beryllium are exceedingly rare. For example, a stable complex with a Be-Be bond, which formally features beryllium in the +1 oxidation state, has been described.<ref name="BCWABe(I)">{{Cite journal |last1=Boronski |first1=Josef T. |last2=Crumpton |first2=Agamemnon E. |last3=Wales |first3=Lewis L. |last4=Aldridge |first4=Simon |date=2023-06-16 |title=Diberyllocene, a stable compound of Be(I) with a Be–Be bond |url=https://www.science.org/doi/10.1126/science.adh4419 |journal=Science |language=en |volume=380 |issue=6650 |pages=1147–1149 |doi=10.1126/science.adh4419 |pmid=37319227 |bibcode=2023Sci...380.1147B |s2cid=259166086 |issn=0036-8075}}</ref> Beryllium in the 0 oxidation state is also known in a complex with a Mg-Be bond.<ref name="Be(0)"/> Beryllium's chemical behavior is largely a result of its small [[atomic radius|atomic]] and [[ionic radius|ionic]] radii. It thus has very high [[ionization potential]]s and does not form divalent cations. Instead it forms two covalent bonds with a tendency to polymerize, as in solid BeCl<sub>2</sub>.<ref name="deGruyter"/>.{{rp|37}} Its chemistry has similarities to that of aluminium, an example of a [[diagonal relationship]].<ref name="Greenwood"/>{{rp|107}}

At room temperature, the surface of beryllium forms a 1−10&nbsp;nm-thick oxide [[Passivation (chemistry)|passivation]] layer that prevents further reactions with air, except for gradual thickening of the oxide up to about 25&nbsp;nm. When heated above about 500&nbsp;°C, oxidation into the bulk metal progresses along grain boundaries.<ref name="Tomastik2005">{{cite journal |last1=Tomastik |first1=C. |last2=Werner |first2=W. |last3=Stori |first3=H. |title=Oxidation of beryllium—a scanning Auger investigation |journal=Nucl. Fusion |date=2005 |volume=45 |issue=9 |page=1061 |doi=10.1088/0029-5515/45/9/005 |bibcode=2005NucFu..45.1061T |s2cid=111381179 |url=https://iopscience.iop.org/article/10.1088/0029-5515/45/9/005}}</ref> Once the metal is ignited in air by heating above the oxide melting point around 2500&nbsp;°C, beryllium burns brilliantly,<ref name="Maček-1969" /> forming a mixture of [[beryllium oxide]] and [[beryllium nitride]]. Beryllium dissolves readily in non-[[oxidizing acid]]s, such as HCl and diluted H<sub>2</sub>SO<sub>4</sub>, but not in [[nitric acid]] or water as this forms the oxide. This behavior is similar to that of aluminium. Beryllium also dissolves and reacts with alkali solutions.<ref name="deGruyter" /><ref name="Greenwood">{{Greenwood&Earnshaw}}</ref>{{rp|112}}

Binary compounds of beryllium(II) are polymeric in the solid state. [[Beryllium fluoride|BeF<sub>2</sub>]] has a [[silica]]-like structure with corner-shared BeF<sub>4</sub> tetrahedra. [[Beryllium chloride|BeCl<sub>2</sub>]] and [[beryllium bromide|BeBr<sub>2</sub>]] have chain structures with edge-shared tetrahedra. [[Beryllium oxide]], BeO, is a white [[refractory]] solid which has a [[zinc sulfide|wurtzite]] crystal structure and a thermal conductivity as high as some metals. BeO is [[amphoteric]]. [[Beryllium sulfide]], [[Beryllium selenide|selenide]] and [[Beryllium telluride|telluride]] are known, all having the [[Cubic crystal system#Zincblende structure|zincblende structure]].<ref name="Wiberg&Holleman">{{Cite book |author=Wiberg, Egon |author2=Holleman, Arnold Frederick |date=2001 |title=Inorganic Chemistry |publisher=Elsevier |isbn=978-0-12-352651-9}}</ref> [[Beryllium nitride]], Be<sub>3</sub>N<sub>2</sub>, is a high-melting-point compound which is readily hydrolyzed. [[Beryllium azide]], BeN<sub>6</sub> is known and [[beryllium phosphide]], Be<sub>3</sub>P<sub>2</sub> has a similar structure to Be<sub>3</sub>N<sub>2</sub>. A number of beryllium [[boride]]s are known, such as Be<sub>5</sub>B, Be<sub>4</sub>B, Be<sub>2</sub>B, BeB<sub>2</sub>, BeB<sub>6</sub> and BeB<sub>12</sub>. [[Beryllium carbide]], Be<sub>2</sub>C, is a refractory brick-red compound that reacts with water to give [[methane]].<ref name="Wiberg&Holleman" /> Beryllium [[silicide|silicides]] have been identified in the form of variously sized [[Nanocluster|nanoclusters]],<ref>{{Cite journal |last1=Fioressi |first1=Silvina |last2=Bacelo |first2=Daniel E. |last3=Binning |first3=R.C. |date=June 2012 |title=A DFT study of dodecahedral beryllium silicide cage clusters |url=https://linkinghub.elsevier.com/retrieve/pii/S000926141200468X |journal=Chemical Physics Letters |language=en |volume=537 |pages=75–79 |doi=10.1016/j.cplett.2012.04.002|bibcode=2012CPL...537...75F }}</ref> formed through a spontaneous reaction between pure beryllium and silicon.<ref>{{Cite journal |last1=Hite |first1=D.A. |last2=Tang |first2=S.-J. |last3=Sprunger |first3=P.T. |date=January 2003 |title=Reactive epitaxy of beryllium on Si(111)-(7×7) |url=https://linkinghub.elsevier.com/retrieve/pii/S0009261402016378 |journal=Chemical Physics Letters |language=en |volume=367 |issue=1–2 |pages=129–135 |doi=10.1016/S0009-2614(02)01637-8|bibcode=2003CPL...367..129H }}</ref> The halides BeX<sub>2</sub> (X = F, Cl, Br, and I) have a linear monomeric molecular structure in the gas phase.<ref name="Greenwood" />{{rp|117}}

Beryllium is a strong electron acceptor leading to Be bonding effects similar to [[hydrogen bonding]].<ref>{{Citation |last1=Montero-Campillo |first1=M. Merced |title=Chapter Three - The beryllium bond |date=2019-01-01 |url=https://www.sciencedirect.com/science/article/pii/S0898883818300394 |work=Advances in Inorganic Chemistry |volume=73 |pages=73–121 |editor-last=van Eldik |editor-first=Rudi |series=Computational Chemistry |publisher=Academic Press |language=en |access-date=2022-10-26 |last2=Mó |first2=Otilia |last3=Yáñez |first3=Manuel |last4=Alkorta |first4=Ibon |last5=Elguero |first5=José |doi=10.1016/bs.adioch.2018.10.003 |s2cid=140062833 |editor2-last=Puchta |editor2-first=Ralph}}</ref>

===Aqueous solutions===
[[File:Beacetate.png|class=skin-invert-image|thumb|left|160px|Schematic structure of [[basic beryllium acetate]]]] 
[[File:BeHydrolysis.png|class=skin-invert-image|thumb|left|190px|Beryllium hydrolysis. Water molecules attached to Be are omitted in this diagram]]
[[File:Be3OHW6.svg|class=skin-invert-image|thumb|left|200px|Structure of the trimeric hydrolysis product of beryllium(II)]]

Solutions of beryllium salts, such as [[beryllium sulfate]] and [[beryllium nitrate]], are acidic because of hydrolysis of the [Be(H<sub>2</sub>O)<sub>4</sub>]<sup>2+</sup> ion. The concentration of the first hydrolysis product, [Be(H<sub>2</sub>O)<sub>3</sub>(OH)]<sup>+</sup>, is less than 1% of the beryllium concentration. The most stable hydrolysis product is the [[trimer (chemistry)|trimeric]] ion [Be<sub>3</sub>(OH)<sub>3</sub>(H<sub>2</sub>O)<sub>6</sub>]<sup>3+</sup>. [[Beryllium hydroxide]], Be(OH)<sub>2</sub>, is insoluble in water at pH 5 or more. Consequently, beryllium compounds are generally insoluble at biological pH. Because of this, inhalation of beryllium metal dust leads to the development of the fatal condition of [[berylliosis]]. Be(OH)<sub>2</sub> dissolves in strongly [[Alkalinity|alkaline]] solutions.<ref name="Lucia">{{cite journal |last1=Alderghi |first1=Lucia |last2=Gans |first2=Peter |last3=Midollini |first3=Stefano |last4=Vacca |first4=Alberto |date=2000 |editor1-last=Sykes |editor1-first=A.G |editor2-last=Cowley |editor2-first=Alan H. |title=Aqueous Solution Chemistry of Beryllium |journal=Advances in Inorganic Chemistry |location=San Diego |publisher=Academic Press |volume=50 |pages=109–172 |doi=10.1016/S0898-8838(00)50003-8 |isbn=978-0-12-023650-3}}</ref>

Beryllium(II) forms few complexes with monodentate ligands because the water molecules in the aquo-ion, [Be(H<sub>2</sub>O)<sub>4</sub>]<sup>2+</sup> are bound very strongly to the beryllium ion. Notable exceptions are the series of water-soluble complexes with the [[fluoride]] ion:<ref>{{cite book|doi=10.1016/S0065-2792(08)60008-4|author=Bell, N.A.|isbn=978-0-12-023614-5|title=Advances in Inorganic Chemistry and Radiochemistry |volume=14 |date=1972 |publisher=Academic Press |location=New York |pages=256–277}}</ref> 

:{{chem2 | [Be(H2O)4](2+) + ''n'' F- <-> Be[(H2O)_{2-''n''}F_{''n''}](2-) + ''n'' H2O }}

Beryllium(II) forms many complexes with bidentate ligands containing oxygen-donor atoms.<ref name="Lucia"/> The species [Be<sub>3</sub>O(H<sub>2</sub>PO<sub>4</sub>)<sub>6</sub>]<sup>2-</sup> is notable for having a 3-coordinate oxide ion at its center. [[Basic beryllium acetate]], Be<sub>4</sub>O(OAc)<sub>6</sub>, has an oxide ion surrounded by a tetrahedron of beryllium atoms.<ref>{{Cite journal |last=Raymond |first=Onyekachi |last2=Perera |first2=Lakshika |last3=Brothers |first3=Penelope J. |last4=Henderson |first4=William |last5=Plieger |first5=Paul G. |date=2015 |title=The chemistry and metallurgy of beryllium |url=https://nzic.org.nz/unsecure_files/cinz/2015-79-3.pdf |journal=Chemistry in New Zealand |volume=79 |issue=3 |pages=137-143}}</ref>

With organic ligands, such as the [[malonate]] ion, the acid deprotonates when forming the complex. The donor atoms are two oxygens.

:{{chem2 | H2A + [Be(H2O)4](2+) <-> [BeA(H2O)2] + 2 H+ + 2 H2O }}
:{{chem2 | H2A + [BeA(H2O)2] <-> [BeA2](2-) + 2 H+ + 2 H2O }}

The formation of a complex is in competition with the metal ion-hydrolysis reaction and mixed complexes with both the anion and the hydroxide ion are also formed. For example, derivatives of the cyclic trimer are known, with a bidentate ligand replacing one or more pairs of water molecules.<ref name="KSMisleadingTitle">{{Cite journal |last1=Kumberger |first1=Otto |last2=Schmidbaur |first2=Hubert |date=December 1993 |title=Warum ist Beryllium so toxisch? |url=https://onlinelibrary.wiley.com/doi/10.1002/ciuz.19930270611 |journal=Chemie in unserer Zeit |language=de |volume=27 |issue=6 |pages=310–316 |doi=10.1002/ciuz.19930270611 |issn=0009-2851}}</ref>

Aliphatic [[hydroxycarboxylic acid]]s such as [[glycolic acid]] form rather weak monodentate complexes in solution, in which the hydroxyl group remains intact. In the solid state, the hydroxyl group may deprotonate: a hexamer, {{chem2|Na4[Be6(OCH2(O)O)6]}}, was isolated long ago.<ref name="KSMisleadingTitle" /><ref>{{cite journal |last1=Rosenheim |first1=Arthur |last2=Lehmann |first2=Fritz |date=1924 |title=Über innerkomplexe Beryllate |journal=Liebigs Ann. Chem. |volume=440 |pages=153–166 |doi=10.1002/jlac.19244400115}}</ref> Aromatic hydroxy ligands (i.e. [[phenol]]s) form relatively strong complexes. For example, log K<sub>1</sub> and log K<sub>2</sub> values of 12.2 and 9.3 have been reported for complexes with [[Tiron (chemical)|tiron]].<ref name="KSMisleadingTitle" /><ref>{{cite journal |last1=Schmidt |first1=M. |last2=Bauer |first2=A. |last3=Schier |first3=A. |last4=Schmidtbauer |first4=H |date=1997 |title=Beryllium Chelation by Dicarboxylic Acids in Aqueous Solution |journal=Inorganic Chemistry |volume=53b |issue=10 |pages=2040–2043 |doi=10.1021/ic961410k |pmid=11669821}}</ref>

Beryllium has generally a rather poor affinity for [[ammine]] ligands.<ref name="KSMisleadingTitle" /><ref name="MDCBMVChelate">{{cite journal |last1=Mederos |first1=A. |last2=Dominguez |first2=S. |last3=Chinea |first3=E. |last4=Brito |first4=F. |last5=Middolini |first5=S. |last6=Vacca |first6=A. |date=1997 |title=Recent aspects of the coordination chemistry of the very toxic cation beryllium(II): The search for sequestering agents |journal=Bol. Soc. Chil. Quim. |volume=42 |page=281}}</ref> There are many early reports of complexes with amino acids, but unfortunately they are not reliable as the concomitant hydrolysis reactions were not understood at the time of publication. Values for log β of ca. 6 to 7 have been reported. The degree of formation is small because of competition with hydrolysis reactions.<ref name="KSMisleadingTitle" /><ref name="MDCBMVChelate" />

===Organic chemistry===

{{Main article|Organoberyllium chemistry}}

Organometallic beryllium compounds are known to be highly reactive.<ref name="naglav">{{cite journal|title=Off the Beaten Track—A Hitchhiker's Guide to Beryllium Chemistry |author=Naglav, D. |author2=Buchner, M. R. |author3=Bendt, G. |author4=Kraus, F. |author5=Schulz, S. |journal=Angew. Chem. Int. Ed. |year=2016|volume= 55|issue=36 |pages= 10562–10576|doi=10.1002/anie.201601809|pmid=27364901 }}</ref> Examples of known organoberyllium compounds are dineopentylberyllium,<ref>{{cite journal |doi=10.1039/J19710001308 |title=Preparation of base-free beryllium alkyls from trialkylboranes. Dineopentylberyllium, bis((trimethylsilyl)methyl)beryllium, and an ethylberyllium hydride |year=1971 |last1=Coates |first1=G. E. |last2=Francis |first2=B. R. |journal=Journal of the Chemical Society A: Inorganic, Physical, Theoretical |page=1308}}</ref> [[beryllocene]] (Cp<sub>2</sub>Be),<ref>{{cite journal|doi=10.1002/cber.19590920233|title=Über Aromatenkomplexe von Metallen, XXV. Di-cyclopentadienyl-beryllium|year=1959|last1=Fischer|first1=Ernst Otto|last2=Hofmann|first2=Hermann P.|journal=Chemische Berichte|volume=92|page=482|issue=2}}</ref><ref>{{cite journal |doi=10.1071/CH9841601 |title=A precise low-temperature crystal structure of Bis(cyclopentadienyl)beryllium |year=1984 |last1=Nugent |first1=K. W. |last2=Beattie |first2=J. K. |last3=Hambley |first3=T. W. |last4=Snow |first4=M. R. |s2cid=94408686 |journal=Australian Journal of Chemistry |volume=37 |page=1601 |issue=8}}</ref><ref>{{cite journal |doi=10.1016/S0022-328X(00)92065-5 |title=The molecular structure of beryllocene, (C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>Be. A reinvestigation by gas phase electron diffraction |year=1979 |last1=Almenningen |first1=A. |journal=Journal of Organometallic Chemistry |volume=170 |page=271 |issue=3 |last2=Haaland |first2=Arne |last3=Lusztyk |first3=Janusz}}</ref><ref>{{cite journal |doi=10.1107/S0567740872004820 |title=Crystal structure of bis(cyclopentadienyl)beryllium at −120&nbsp;°C |year=1972 |last1=Wong |first1=C. H. |last2=Lee |first2=T. Y. |last3=Chao |first3=K. J. |last4=Lee |first4=S. |journal=Acta Crystallographica Section B |volume=28 |page=1662 |issue=6|bibcode=1972AcCrB..28.1662W }}</ref> diallylberyllium (by exchange reaction of diethyl beryllium with triallyl boron),<ref>{{cite journal |doi=10.1002/zaac.19744050111 |title=Ein Beitrag zur Existenz von Allylberyllium- und Allylaluminiumverbindungen |language=de |year=1974 |last1=Wiegand |first1=G. |last2=Thiele |first2=K.-H. |journal=Zeitschrift für Anorganische und Allgemeine Chemie |volume=405 |pages=101–108}}</ref> bis(1,3-trimethylsilylallyl)beryllium,<ref>{{cite journal |doi=10.1002/anie.201001866 |pmid=20575128 |title=Bis(1,3-trimethylsilylallyl)beryllium |year=2010 |last1=Chmely |first1=Stephen C. |last2=Hanusa |first2=Timothy P. |last3=Brennessel |first3=William W. |journal=Angewandte Chemie International Edition |volume=49 |issue=34 |pages=5870–5874}}</ref> Be([[Mesitylene|mes]])<sub>2</sub>,<ref name="naglav" /> and (beryllium(I) complex) diberyllocene.<ref name="BCWABe(I)" /> Ligands can also be aryls<ref>{{cite journal |doi=10.1021/ic00061a031 |title=Synthesis and structural characterization of the beryllium compounds [Be(2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)<sub>2</sub>(OEt<sub>2</sub>)], [Be{O(2,4,6-tert-Bu<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)}<sub>2</sub>(OEt<sub>2</sub>)], and [Be{S(2,4,6-tert-Bu<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)}<sub>2</sub>(THF)]⋅PhMe and determination of the structure of [BeCl<sub>2</sub>(OEt<sub>2</sub>)<sub>2</sub>] |year=1993 |last1=Ruhlandt-Senge |first1=Karin |last2=Bartlett |first2=Ruth A. |last3=Olmstead |first3=Marilyn M. |last4=Power |first4=Philip P. |journal=Inorganic Chemistry |volume=32 |issue=9 |pages=1724–1728}}</ref> and alkynyls.<ref>{{cite journal |doi=10.1016/S0022-328X(00)87485-9 |title=The crystal structure of dimeric methyl-1-propynyl- beryllium-trimethylamine |year=1971 |last1=Morosin |first1=B. |journal=Journal of Organometallic Chemistry |volume=29 |pages=7–14 |last2=Howatson |first2=J.}}</ref>