Boron: Inorganic Chemistry

Abstract

Boron is unique among the elements and displays remarkable chemistry in all of its compounds. It is widely distributed at low concentrations on the Earth and is virtually always found bound to oxygen in its natural forms. Boron enters into the life cycle of and is an essential element for plants and animals. The vast majority of industrial uses of boron on a weight basis also involve boron–oxygen compounds, including important mineral sources, metal borates, boric acid, boric oxide, and boric acid esters. These find large‐scale applications in many industries, most notably in the manufacture of glass and other vitreous materials. Boric acid is a weak Lewis acid and does not display Brønsted acidity in aqueous solution. The condensation of B(OH) 3 and B(OH) 4 − species to form polyborates in relatively concentrated borate solutions has important implications for the solubilities and other solution properties of metal and nonmetal borate salts. Boric acid reacts with alcohols and other hydroxyl group‐bearing compounds to form esters, which find many industrial uses. Reversible borate ester crosslinking leads to polymer gel formation and provides the basis for the essential biological role of boron. Nonoxide boron compounds also have important industrial uses. These include refractory compounds, such as boron carbide, boron nitrides, boron phosphides, elemental boron, and metal–boron alloys, as well as nonrefractories, such as the boron halides. Nonrefractory boron–phosphorus and boron–sulfur compounds and the boron subhalides are yet to find significant industrial use, yet, nonetheless exhibit fascinating chemistries.

In situ detection of boron by ChemCam on Mars

“…Nevertheless, the vein geological context points to emplacement of boron by water. Boron is very easily oxidized; boron is always a borate in conditions where water is stable and in past and present Mars surface oxygen fugacity conditions, which implies that the boron was a borate when emplaced and remains a borate at present [ Ingri , ; Schubert , ]. We suggest that the boron was at least partly emplaced by a late‐stage groundwater and was likely redistributed from a primary source [cf.…”

“…Both models considered suggest that boron (a) weathered out of primary igneous crust in the Gale crater watershed [ Ehlmann and Buz , ], (b) was dissolved in lake water, and (c) was dissolved in the late‐stage groundwater system. However, the different possible mechanisms of initial boron concentration from lake waters have important consequences for fluid pH and the resultant borate mineralogy, since possible borate mineral precipitates are dependent on fluid temperature, pH, and composition [ Hunt et al , ; Garrett , ; Schubert , ].…”

Synthesis, spectroscopic and thermal characterization of non-metal cation (nmc) pentaborates salts containing 2-amino-5-nitropyridine and 2-amino-6-methylpyridine as cation

“…These properties may lead to previously unobserved borate structural moieties and further offers the opportunity to explore structure directing H-bond relationships. Indeed, the guanidinium and imidizolium poyborate systems both display the isolated nonaborate anion, [B 9 O 12 (OH) 6 ] -3 , and this anion is only observed with these non-metal cations [23]. More recently some template complexed metal cation/ pentaborate anion salts have been characterized [24].…”

“…When finely divided, it is attacked slowly by hot concentrated hydrogen peroxide, hot concentrated nitric acid, hot sulfuric acid or hot mixture of sulfuric and chromic acids [4]. Boron is always found in nature combined with oxygen as anhydrous mixed metal oxides or as hydrated metal borates, with more than 200 borate minerals known and more than 100 were structurally characterized [5][6][7]. Borate materials have attracted a great deal of attention in the past decades because of their…”

Cotemplating Synthesis of a Rare Borate Ni(en)3·Hen·[B9O13(OH)4]·H2O with a Chiral Polyanonic Chain Constructed from Two Different Clusters

“…Great attention has been paid to the hydro- or solvothermal preparation of templated borates, owing to their intriguing variety of architectures and potential applications, such as mineralogy, nonlinear optics, and photoluminescence . Boron is of particular interest because it shows flexible coordination numbers, namely, [BO 3 ] triangle and [BO 4 ] tetrahedron, which have the ability to form a great variety of boron–oxygen (BO) polyanions, − including B 5 O 6 (OH) 4 – , B 3 O 3 (OH) 4 – , B 4 O 5 (OH) 4 2– , B 3 O 3 (OH) 5 2– , B 8 O 10 (OH) 6 2– , and so on. It is believed that the synthesis of these polyanions are mainly dependent upon the boron concentration, pH, and temperature .…”