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The shortest-lived is 7 B, with a half-life of a mere 350±50 × 10 −24 s, being the boron isotope with the fewest neutrons and a half-life long enough to measure. Some radioisotopes have important roles in scientific research; a few are used in the production of goods for commercial use or, more rarely, as a component of finished products.
Selenium, which is an essential element for animals and prokaryotes and is a beneficial element for many plants, is the least-common of all the elements essential to life. [ 3 ] [ 63 ] Selenium acts as the catalytic center of several antioxidant enzymes, such as glutathione peroxidase , [ 11 ] and plays a wide variety of other biological roles .
For example, boron trifluoride (BF 3) combines eagerly with fluoride sources to give the tetrafluoroborate anion, BF 4 −. Boron trifluoride is used in the petrochemical industry as a catalyst. The halides react with water to form boric acid. [51] Other boron halides include those with B-B bonding, such as B 2 F 4 and B 4 Cl 4. [55]
In biochemistry, an ultratrace element is a chemical element that normally comprises less than one microgram per gram of a given organism (i.e. less than 0.0001% by weight), but which plays a significant role in its metabolism.
Thus boron is not a candidate for life. [38] Arsenic is toxic to life, and its possible candidacy has been rejected. [39] [40] In the past (1960s-1970s) other candidates for life were plausible, but with time and more research, only carbon has the complexity and stability to make large molecules and polymers essential for life. [41] [42] [43]
Boron deficiencies effecting seed yields and pollen fertility are common in laterite soils. [45] Boron is essential for the proper forming and strengthening of cell walls. Lack of boron results in short thick cells producing stunted fruiting bodies and roots. Deficiency results in the death of the terminal growing points and stunted growth.
Alkylideneboranes (RB=CRR) with a boron–carbon double bond are rare. One example, HB=CH 2, can be detected at low temperature. The derivative CH 3 B=C(SiMe 3) 2 is fairly stable, but prone to cyclodimerisation. [19] Some boron-substituted heterocycles are aromatic, but very few such arenes are stable. In borabenzene, boron replaces one CH ...
The mean oxidation number for the boron atoms is then simply the ratio of hydrogen to boron in the molecule. For example, in diborane B 2 H 6, the boron oxidation state is +3, but in decaborane B 10 H 14, it is 7 / 5 or +1.4. In these compounds the oxidation state of boron is often not a whole number.