The Discovery of Boron

The element boron was discovered in 1808. A gray powder of boron was formed in the reaction between potassium metal and boric add. This discovery was made by J.-L. Gay-Lussac and L. J. Thenard in Paris and almost simultaneously by Sir Humphry Davy in London. That the name for the new element should contain the syllable bor was natural due to its origin in borax. Davy saw similarities between the new element and carbon, and found it logical to use the name boron. It also became the name of the element in the English language. 

The Frenchman Henry Moissan manufactured boron industrially in 1895 by reduction of boron trioxide B Oj with magnesium. 

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The discovery of boron deltahedra in elemental boron and metal borides and later in polyhedral boranes generated an interest in computational studies on these structures as soon as suitable computational methods became available. The earliest computational work on boron deltahedra was the 1954 study by Longuet-Higgins and Roberts on the Be octahedra found in metal boride studies using the secular determinants obtained from linear combinations of atomic orbitals (LCAO). This work was followed shortly by a study of boron icosahedra which predicted the existence of a stable anionic icosahedral... 

Boron was known to the ancients in the form of borax, which was used for various types of glass. Boron is almost always found directly bound to oxygen and is difficult to prepare in pure form. In 1808 the ebullient chemist Sir Humphry Davy, whom we encountered as the discoverer of potassium and sodium (p. 324) as well as magnesium, calcium, strontium, and barium (p. 355), was just barely beaten (by 9 days) to the discovery of boron by the French chemists Joseph Louis Gay-Lussac and Louis Jacques Thenard. Yes, this is the same Gay-Lussac who proved (in 1802) that the volume of a gas is directly proportional to the temperature. (Jacques Charles, a French physicist, actually formulated this relationship some 15 years earlier, but... 

Since the discovery of buckminsterfullerene (C o) [85NAT(318)162] and other fullerenes (Cig. C70), these molecules have been intensely studied, both experimentally and theoretically. Likewise, several reports on heterofullerenes containing heteroatoms such as nitrogen and boron have appeared (91JPC4948 91JPC10564). The incorporation of heteroatoms is expected to modify the structural and electronic features of these structures, and have thus attracted some interest. 

As is well known, many experimental smdies have been made extensively to search for a possibility of encapsulation of atoms by hollow fullerenes since the discovery of Cgo by Kroto et al. [143]. These methods, however, usually require high tempratures and high pressures, or ion implantation. The yields are also as low as 0.4—10 %. In this sense, the efficiency in our case is much higher and the required conditions are much milder with collison energy of 2 eV. However, the boron substimtion is a bottle neck, although Smalley and co-workers successfully synthesized boron-doped fullerenes [144]. 

Our third approach to 27 addressed the unavailability of 3-methoxy-2-cyclopentenone (31) in bulk quantities which necessitated the discovery of an alternative route (Scheme 7.7). Fortunately, the precursor to 31,1,3-cyclopentandione (35), was available in the required quantities and our efforts shifted to the use of this reagent Bromination of 35 with NBS, employing either KHC03 or KOH as the base, gave brominated dione 36 in 85% isolated yield. Unfortunately, direct cross-coupling of alkyl bromide 36 with boronic acid 12 under a variety of Suzuki-... 

But the discovery of the carboranes in the early 1960s revealed that bonding possibilities other than simple o-- or 7r-bonds between B and C centers were necessary to understand the structure of such compounds as 1,5-dicarba-closo-pentaborane(5) [6 in Eq. (1)], which is obtained in low yield in an electrical discharge.6 Ordinary valence conventions cannot account for the bonding of boron to five other atoms, and hence the concept of electron-deficient bonding must be invoked for boron. Although carbon seems to adhere to normal tetravalence, again it should be remembered... 

The discovery of polyhedral boranes and polyhedral heteroboranes, which contain at least one atom other than in the cage, initiated a new era in boron chemistry.1-4 Most commonly, of the three commercially available isomeric dicarba-closo-dodecaborane carboranes(l,2-, 1,7-, and 1,12-), the 1,2-isomer 1 has been used for functionalization and connection to organic molecules. The highly delocalized three-dimensional cage bonding that characterizes these carboranes provides extensive thermal and kinetic stabilization as well as photochemical stability in the ultraviolet and visible regions. The unusual icosahedral geometry of these species provides precise directional control of all exopolyhedral bonds. 

The discovery of 1 (1), in 1970, opened a new and fascinating chapter of organometallic chemistry. This cation was the first compound derived from the hypothetical borabenzene 2 and the first complex of a classical boron-carbon ligand. Since then approximately 100 borabenzene derivatives, mainly complexes of 3d metals, have been characterized. Other unsaturated boron-carbon systems have been shown to act as ligands to metals (2). This development has also strongly stimulated the challenging quest for the simple species 2-5. 

The mechanism of initiation of cationic polymerisations by metal halides was clarified and systematized to some extent by the discovery of the phenomenon of co-catalysis or co-initiation. But, whereas there was, by the mid-1960s, good evidence that at any rate in many systems the halides of boron, titanium, and tin required a co-initiator, the position with regard to the best-known and most popular initiator, and the one which was of greatest economic significance, aluminium chloride, remained obscure. Of the vast number of published experiments on the system, aluminium chloride + isobutylene, hardly any could provide evidence concerning the initiation reaction, because they were almost exclusively concerned with measurements of yields and degree of polymerisation (DP). 

The discovery of gallium was followed by the discovery of scandium (Mendeleev s eka-boron) in 1879 and of germanium (eka-sili-con) in 1886. The new elements had the approximate atomic weights and properties that Mendeleev had predicted. The scientific world was astonished. It is probably safe to say that before Mendeleev s predictions were confirmed, no chemist would have believed that the properties of unknown elements could be predicted with such accuracy. 

After commenting on the discovery of gallium, scandium, and germanium (eka-aluminum, eka-boron, and eka-silicon), D. I. Mendeleev had written in 1891, I foresee some more new elements, but not with the same certitude as before. I shall give one example, and yet I do not see it quite distinctly (7). He had then proceeded to describe an undiscovered dvi tellurium with an atomic weight of about 212. Since polonium resembles tellurium and has an estimated atomic weight of about 210, it is probably the realization of Mendeleev s dvi tellurium. ... 

Even before the discovery of the katapinands vide supra), work upon bidentate Lewis acid hosts suggested the possibility of chelation of anionic sjjecies by acyclic-boron-containing ligands such as BF2CH2CH2BF2. In many ways mul-... 

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