Nitrogen-boron bonds

There is the possibility of building up an extensive systematic chemistry of compounds containing boron-nitrogen bonds, analogous to the chemistry of carbon-carbon bonds but the reactivity of the B—bond is much greater than that of the C—C bond, so that we get physical, but not chemical, resemblances between analogous compounds. 

Other reactions adapted from asymmetric aldol reactions suffer in comparison from the fact that (probably due to the strength of the boron-nitrogen bond) boron-mediated processes generally yield the intermediate 2-halo-3-aminoester products rather than aziridine products directly [51]. 

The difference between a single and a double bond distance is nearly 20 pm but it is only 15 pm between a double and a triple bond. Boron-nitrogen bonds are longer than the corresponding C—C bonds, the difference being nearly 5 pm for the single bonds and nearly 8 pm for the double and triple bonds. 

The boron-nitrogen bonded isomer, trimethylamine-isocyanoborane adduct,9"13... 

The structure of this adduct has been determined by X-ray diffraction 144> and confirms the 2112 topology of the B4Hg framework. Furthermore, in agreement with the original conclusion 143>, the adduct contains a boron-phosphorus bond rather than a boron-nitrogen bond. 

If one assumes participation of the pi-electrons of nitrogen in the boron-nitrogen bonding according to... 

Mass spectroscopic studies on 1,3,2-diazaboracydoalkanes 18> seem to reveal some interesting aspects. It appears that dehydrogenation at annular carbon atoms under electron impact is readily accomplished. This observation tends to indicate that the resultant products may be stable and suggests research in this area. Moreover, it is noteworthy that in all the spectra which have been studied so far, no complete breakdown of the molecules was observed. Instead, species with one of the two original boron-nitrogen bonds left intact appear to be rather stable and there seems to be a particular tendency for the intramolecular formation of boron-containing species with one B—N and at least one B—C bond. Also, a characteristic breakdown pattern in all of the studied spectra of 1,3,2-diazaboracycloalkanes seems to be established inasmuch as the ready loss of exocyclic groups other than those attached to the boron atom has been observed. 

Fjeldberg, T., G. Gundersen, T. Jonvik, H. M. Seip, and S. Saebo (1980). Ah initio studies of some trivalent boron compounds with boron-oxygen and boron-nitrogen bonds. Acta. Chem. Stand. A34, 547-65. 

Poly(iminoborane)s [(-BR=N-)n] are a potential 7t-conjugated polymers, since boron-nitrogen bonds possess the double bond like nature owing to pTt-pjt interaction However, these materials are not fully characterized so far 10>. In order to incorporate the monomeric B-N bond into the conjugation path, we examined an alternating boration copolymerization between diisocyanates and diynes making use of different reactivity between haloboration and phenylboration reactions. 

Diorganobis(dimethylamino)diborane(4) derivatives react with carbon dioxide or carbon disulfide in petroleum ether to form the products of insertion into the boron-nitrogen bond (1) ... 

Problem 10.5 The compound borazoie, B3N3H6, is shown by electron diffraction to have a flat cyclic structure with alternating boron and nitrogen atoms, and all boron-nitrogen bond lengths the same, (a) How would you represent borazole by valence-bond structures (b) In terms of orbitals (c) How many tt electrons arc there, and which atoms have they come from ... 

Exchange with R3AI 5.3.3.5.4 Reaction with boron—nitrogen bonds ... 

Table 12.2 Boron-nitrogen bond distances in selected neutral species all data are from X-ray...

B. Reactions Leading to Formation of Boron-Nitrogen Bonds. 285... 

---