A metaborate is an

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

(negative

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

) consisting of

boron Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the ''boron group'' it has th ...

and

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

, with

empirical formula In chemistry, the empirical formula of a chemical compound is the simplest whole number ratio of atoms present in a compound. A simple example of this concept is that the empirical formula of sulfur monoxide, or SO, would simply be SO, as is th ...

; or any

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...

with such anions, such as

sodium metaborate Sodium metaborate is a chemical compound of sodium, boron, and oxygen with formula . However, the metaborate ion is trimeric in the anhydrous solid, therefore a more correct formula is or . The formula can be written also as · to highlight the ...

, or calcium metaborate . It is one of the boron

oxoanion An oxyanion, or oxoanion, is an ion with the generic formula (where A represents a chemical element and O represents an oxygen atom). Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determine ...

s or

borate A borate is any of several boron oxyanions, negative ions consisting of boron and oxygen, such as orthoborate , metaborate , or tetraborate ; or any salt with such anions, such as sodium metaborate, and disodium tetraborate . The name also refe ...

s In aqueous solutions this anion

hydrolyzes Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis ...

tetrahydroxyborate Tetrahydroxyborate is an inorganic anion with the chemical formula or . It contributes no colour to tetrahydroxyborate salts. It is found in the mineral hexahydroborite, , originally formulated . It is one of the boron oxoanions, and acts as a ...

. For this reason, solutions or

hydrated Drinking is the act of ingesting water or other liquids into the body through the mouth, proboscis, or elsewhere. Humans drink by swallowing, completed by peristalsis in the esophagus. The physiological processes of drinking vary widely among o ...

salts of the latter are often improperly named "metaborate".

Structure

Solid state

In the solid state

salts In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively cha ...

, metaborate is often an

oligomeric In chemistry and biochemistry, an oligomer () is a molecule that consists of a few repeating units which could be derived, actually or conceptually, from smaller molecules, monomers.Quote: ''Oligomer molecule: A molecule of intermediate relativ ...

polymeric A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic an ...

anion, conceptually resulting from the fusion of two or more through shared oxygen atoms. In these anions, the boron atom forms covalent bonds with either three or four oxygen atoms. Some of the structures are * A trimer with formula or , consisting of a six-member ring of alternating boron an oxygen atoms with three extra oxygen atom attached to the borons. This form is found, for example, in some anhydrous

alkali metal The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K),The symbols Na and K for sodium and potassium are derived from their Latin names, ''natrium'' and ''kalium''; these are still the origins of the names ...

salts like

or potassium metaborate, in α- and β- barium metaborate , and in the mixed salt potassium cadmium metaborate . The three distances are nearly equal in the

potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...

salt (133.1, 139.8, and 139.8 pm) but significantly different in the

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...

one (128.0, 143.3, and 143.3 pm). * An unbounded chain of units connected by single shared-oxygen bridges; that is, . Occurs in calcium metaborate or . * A tridimensional network of tetrahedral groups, as in "zinc metaborate", actually the mixed salt zinc metaborate oxide with elemental formula . * A tridimensional regular array of tetrahedra sharing vertices, as in the high-pressure and high-temperature γ form of

lithium metaborate Lithium metaborate is a chemical compound of lithium, boron, and oxygen with elemental formula . It is often encountered as a hydrate, , where ''n'' is usually 2 or 4. However, these formulas do not describe the actual structure of the solids. ...

Aqueous solution

The cyclic trimer anions dissociate almost completely in solution giving mainly

anions: : + 6 3 Other molecules and anions, such as , , , and are less than 5% at 26 °C. In 1937, Nielsen and Ward claimed that the metaborate anion in solution has a linear symmetric structure with negative charges on the oxygens and a positive charge on the boron. This claim has been challenged, however.

Gas phase

The vapor of

cesium metaborate Caesium (IUPAC spelling) (or cesium in American English) is a chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of , which makes it one of only five elemental metals that ...

has neutral monomers and dimers as well as ionized versions thereof. The same situation holds for

thalium metaorate Thallium is a chemical element with the symbol Tl and atomic number 81. It is a gray post-transition metal that is not found free in nature. When isolated, thallium resembles tin, but discolors when exposed to air. Chemists William Crookes and ...

Solid solutions

In 1964 Hisatsune and Surez investigated the

infrared spectrum Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

of metaborate anions in dilute solid solutions of potassium salt in alkali

halide In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fluor ...

s such as

potassium chloride Potassium chloride (KCl, or potassium salt) is a metal halide salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous crystal appearance. The solid dissolves readily in water, and its solutions have a salt ...

Preparation

References

P. Ney, M. D. Fontana, A. Maillard, and K. Polgár (1998): "Assignment of the Raman lines in single crystal barium metaborate (β-BaB2O4)". ''Journal of Physics: Condensed Matter'', volume 10, issue 3, pages 673-. David H. Feather and Alfred Buechler (1973): "Gaseous thallium(I) metaborate and thallium(I) aluminum fluoride". ''Journal of Physical Chemistry'', volume 77, issue 12, pages 1599–1600. Yongquan Zhou, Souta Higa, Chunhui Fang, Yan Fang, Wenqian Zhang, and Toshio Yamaguchi (2017): "B(OH)4− hydration and association in sodium metaborate solutions by X-ray diffraction and empirical potential structure refinement". ''Physical Chemistry Chemical Physics'', volume 19, pages 27878-27887 W. H. Zachariasen (1931): "The Crystal Lattice of Calcium Metaborate, CaB2O4". ''Proceedings of the National Academy of Sciences (PNAS)'', volume 17, issue 11, pages 617-619. Y. Roussigné, R. Farhi, C. Dugautier, and J. Godard (1992): "A Raman study of both phases of barium metaborate (BBO)". ''Solid State Communications''. volume 82, issue 4, pages 287-293. Yongquan Zhou, Chunhui Fang, Yan Fang, Fayan Zhu, Song Tao, Sha Xu (2012): "Structure of aqueous sodium metaborate solutions: X-ray diffraction study". ''Russian Journal of Physical Chemistry, volume 86, issue 8, pages 1236–1244. Fayan Zhu, Yongquan Zhou, Chunhui Fang, Yan Fang, Haiwen Ge, and Hongyan Liu (2017): "Ion association in lithium metaborate solution: a Raman and ab initio insight". ''Physics and Chemistry of Liquids'', volume 55, issue 2, pages 186-195. Mitsuru Asano, Yoshihiko Yasue, and Kenji Kubo (1984): "Mass Spectrometric Study of Ions Formed from Cesium Metaborate Vapor under Electron Impact". ''Journal of Nuclear Science and Technology'', volume 21, issue 8,pages 614-624. C. S. Willand and A. C. Albrecht (1986): "The second-order nonlinear optical properties of β-barium metaborate: A semiempirical theoretical investigation". ''Optics Communications'', volume 57, issue 2, 15 February , Pages 146-152. Shifeng Jin, G. Chai, J. Liu, W. Wang and X. Chen (2009): "The centrosymmetric metal meta-borate KCdB₃O₆". ''Acta Crystallographica Section C'', volume C65, issue 7, pages i42-i44. Robert K. Momii and Norman H. Nachtrieb (1967): "Nuclear Magnetic Resonance Study of Borate-Polyborate Equilibria in Aqueous Solution". ''Inorganic Chemistry'', volume 6, issue 6, pages 1189-1192. I. C. Hisatsune and Noelia Haddock Suarez (1964): "Infrared Spectra of Metaborate Monomer and Trimer Ions". ''Inorganic Chemistry'', volume 3, issue 2, pages 168-174. J. Rud Nielsen and N. E. Ward (1937): "Raman Spectrum and Structure of the Metaborate Ion". ''The Journal of Chemical Physics'', volume 5, Issue 3, page 201 M. Marezio, H. A. Plettinger and W. H. Zachariasen (1963): "The bond lengths in the sodium metaborate structure", ''Acta Crystallographica'', volume 16, pages 594-595. M. Marezio, H. A. Plettinger and W. H. Zachariasen (1963): "Refinement of the calcium metaborate structure". ''Acta Crystallographica'', volume 16, pages 390-392. M. Marezio and J. P. Remeika (1966): "Polymorphism of LiMO2 Compounds and High‐Pressure Single‐Crystal Synthesis of LiBO2". ''Journal of Chemical Physics'', volume 44, issue 9, pages 3348-. W. Schneider and G. B. Carpenter (1970) "Bond lengths and thermal parameters of potassium metaborate, K3B3O6". ''Acta Crystallographica - Section B'' volume B26, pages 1189-1191 (1964): "The crystal structure of anhydrous zinc metaborate Zn4O(BO2)6". ''Zeitschrift für Kristallographie'', volume 119, issue 5-6 (1961): "A new structural type of metaborate anion". ''Zeitschrift für Kristallographie'', volume 115, issue 5-6. W. H. Zachariasen (1937): "The Crystal Structure of Potassium Metaborate, K3(B3O6)". ''Journal of Chemical Physics'', volume 5, issue 11, page 919. {{chem-stub Borate minerals Industrial minerals Inorganic compounds Oxyanions