Borazine-phosphazene

A theoretical study on the structures, magnetical properties, and energetics of phosphorus analogues of borazine, E2G3H6 191 (E = B, Al, Ga G = N, P, As), compared to those of other borazine analogues, E3J3H3 192 (J = O, S, Se) and to phosphazene (194),234 shows that results could vary with function of the reference system. Some compounds with P and As heteroatoms were found to prefer nonplanar geometries (Scheme 74). Contradictory results were... 

IF the product were a monomer, its structure could be drawn as Cl2PsN, which is analogous to organic nitriles. R—C=N. For this reason the original names used for these compounds were phosphonitriles, phosphonitrilic chloride, etc. However, the products are actually either cyclic or linear polymers of general formula [NPC ,] . Thus, by analogy with benzene, borazine. etc., these compounds hove become known as phosphazenes. The rn jor product of the reaction in Eq. 16.47 and the easiest to... 

Because London forces increase greatly with polarizability, many larger molecules form liquids or even solids at room temperature despite having only this type of attraction between molecules. Examples are NifCO) (bp = 43 °C), CCI4 (bp = 77 °C), borazine, (bp = 53 °C), and trimeric phosphazene. P3N3CI6 (mp =... 

Condensation processes are used to prepare oligomers of organosiloxanes, silazanes, silthianes, borazines, borazanes, metaborates, metaphosphates, phosphazenes, thiazyls, alazanes, metal oxides and so on. 

Major covalent nitrides include those of boron, sulfur, and phosphorus. Some indication of the nature of the phosphorus nitrides (the phosphazenes) was given in the last section. Boron nitrides have rather similar formulas but involve >77 77 B=N bonds instead of dir—pir P=N bonds. Figure 16.7 shows borazine, sometimes known as inorganic benzene. Note that two resonance structures are necessary to describe this molecule using valence-bond concepts. Experimentally, we find that all the B—N bonds have the same bond length, intermediate between that characteristic of single and double bonds. (Sulfur nitrides will be discussed in Chapter 17.)... 

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