Editing Beryllium (section)

===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" />