Benzene inorganic

The cyclic borazine (-BH-NH-)3 and its derivatives form one of the largest classes of B-N compounds. The parent compound, also known as inorganic benzene , was first isolated as a colourless liquid from the mixture of products obtained by reacting B2H6 and NH3 (A. Stock and E. Pohland, 1926) ... 

Borazine, B3N3Hft, a compound that has been called inorganic benzene because of its similar hexagonal structure (but with alternating B and N atoms in place of C atoms), is the basis of a large class of boron—nitrogen compounds. Write its Lewis structure and predict the composition of the hybrid orbitals used by each B and N atom. 

The best known boron-containing ring systems are the so-called inorganic benzenes, namely, borazine (71), boroxine (72), and triphosphatriborin (73) (Fig. 46), which are isoelectronic and isostructural with benzene. These ring systems are obtained by the interaction of boron with nitrogen, oxygen, and phosphorus, respectively.4... 

Boron also forms many other compounds with nitrogen. One of the most interesting of these is bora-zine, B3N3HS (m.p. -58 °C, b.p. 54.5 °C). Shown here is the structure ofborazine, which is similar to the structure of benzene. In fact, borazine has sometimes been referred to as "inorganic benzene."... 

Borazine, 21, is sometimes called inorganic benzene. Like benzene, it achieves a high-symmetry D6h equilibrium structure with equivalent NRT bond orders (1.380)... 

The inorganic benzene borazine has been shown to undergo electrophilic substitution in a manner very similar to benzene itself. Does the electrophile attack at or N Use orbital interaction theory to predict the site of attack. Compare this with the prediction on the basis of an SHMO calculation and experimental findings (Chia-varino, B. Crestoni, M. E. Di Marzio, A. Fomarini, S. Rosi, M., J. Am. Chem. Soc., 1999,121, 11204-11210). 

Borazine is isoelectronic with benzene, as B=N is with C=C, (Fig. 16.21). in physical properties, borazine is indeed a close analogue of benzene. The similarity of the physical properties of the alkyl-substituted derivatives of benzene and borazine is ever more remarkable. For example, the ratio of the absolute boiling points of the substituted borazines to those of similarly substituted benzene is constant. This similarity in physical properties led to a labeling of borazine as "inorganic benzene." This is a misnomer because tbe chemical properties of borazine and benzene are quite different Both compounds have aromatic rr clouds of electron density with potential for delocalization over all of the ring atoms. Due to the difference m electronegativity between boron and nitrogen, the cloud in borazine is "lumpy" because more electron... 

Clear theoretical evidence is presented to show that the u-electron systems of benzenoid aromatic molecules are described well in terms of localized, non-orthogonal, singly-occupied orbitals. The characteristic properties of molecules such as benzene or naphthalene arise from a profoundly quantum mechanical phenomenon, namely the mode of coupling of the electron spins, rather than from any supposed delocalization of the orbitals. Other systems considered include azobenzenes, such as pyridine, five-membered rings, such as furan, and inorganic heterocycles, such as borazine ( inorganic benzene ). 

The spin-coupled method has now been applied to a large number of aromatic systems benzene and naphthalene azobenzenes, such as pyridine, pyridazine, pyrimidine and pyrazine five-membered rings, such as furan, pyrrole, thiophen, and thiazole and inorganic heterocycles, such as borazine ( inorganic benzene ) and boroxine, for which we find little evidence of aromaticity. Structural formulae are collected in Fig. 1. For all of these molecules we have included the effects of electron correlation for the Jt electrons but not for the a framework. This a-n separation is an approximation whose utility rests upon the chemistry of aromatic systems — to abandon it would be to ignore this entire body of experience. Furthermore, very extensive calculations [4] have demonstrated that rc-electron only correlation affords an excellent description of ground and excited states of benzene. 

At first, N-heterocyclic carbenes 20 look bizarre to the organic chemist, since they are organic/inorganic hybrid compounds. However, borazines, sometimes called inorganic benzene , are isoelectronic with benzene and are therefore extraordinarily stable heterocycles. Exchange of a borane... 

An important observation supporting the need for resonance in the LE model is that there are only three different structures of dichlorobenzene (C6H4C12). How does this fact support the need for the concept of resonance Borazine (B3N3H6) has often been called inorganic benzene. Draw Lewis structures for borazine. Borazine is a six-membered ring of alternating boron and nitrogen atoms. 

Parallels between main group and organic chemistry can be instructive. One of the best known of these parallels is between the organic molecule benzene and the isoelectronic borazine (alias inorganic benzene ), B3N3Hg. Some of the similarities in physical properties between these two are striking, as shown in Table 8-6. 

Borazine (B3N3H6) is sometimes called inorganic benzene because its structure shows some formal similarity with benzene, with delocalized electrons and aromatic character. 

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