Boron-Nitrogen Chains

The reaction of diborane(6) with bis or tris(dimethylamino)borane has recently been shown to be synthetically useful in the stepwise buildup of a boron-nitrogen chain leading to bis( -dimethylamino)triborane(9).7... 

The vapor pressure of /i-[(CH3)2N]B2H5 obeys the relationship log P = 2158.56/T + 1.75 log T - 0.008061T + 7.518831 (101 torr at 0°). The gas-phase infrared spectrum has been reported in detail.5 The compound is a useful intermediate in the synthesis of other boron nitrogen compounds, including those containing NBNB6 and PBNB7 chains, and Na[(CH3)2-N(BH3)2].8 The compound can be stored at 25° for months in sealed, evacuated Pyrex tubes. It is soluble in ethers and aromatic hydrocarbons, but is attacked by protic solvents. 

I. Inorganic siloxane, sulfur chains, black phosphorus, boron-nitrogen, silicones. 

Centered boron, nitrogen and carbon (and dicarbon) give one group of infinite chain structures, while many centered heterometals afford another. 

The same phenomenon is observed in boron-nitrogen polymers. Borazines with a - BR—NR -)- chain are heat stable up to 400-500 C but are readily hydrolyzed. The parquet polymer, boronitride (BN) , on the other hand, is very resistant to hydrolysis and oxidation and can be used up to temperatures of 2000°C. Boron-oxygen compounds are heat stable but are readily hydrolyzed. Boron-carbon compounds are similarly heat stable but are very prone to oxidation. 

Boron-nitrogen coordination polymers with ferrocene in the main chain have also been obtained by reacting... 

The great number of compounds of boron is due to the readiness with which boion atoms fonn, to some extent, chain structures with other boion atoms, and, to a far greater extent, cyclic compounds, both with other boron atoms, mid with atoms of carbon, oxygen, nitrogen, phosphorus, arsenic, the halogens, and many other elements. Examples of Lhcm arc shown below, beginning with the two pentaboranes B5 Hc> and Bs Hu ... 

If carbon atoms inside polyacetylenic chains are substituted by nitrogen atoms, positively-charged nitrilium or isonitrilium centers result boron substitution leads to negatively-charged centers. No experimental or theoretical data are yet available on such systems, which (if charges would be correctly placed) would benefit from electrostatic interactions, in addition to Van der Waals forces. 

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