The Chemistry of Phosphorus

A selection of phosphorus-containing compounds, which illustrate the various coordination numbers that phosphorus can adopt in its compounds. 

Phosphorus is found in oxidation number -i-5 in species such as [PC14], PF5 and [PFd . 

As we shall see in the following Sections, phosphorus also forms a number of cage structures based on expansion of the P4 tetrahedron, containing three- or four-coordinate phosphorus. It has also been found to form ring or chain structures from linked tetrahedra, with oxygen or nitrogen substituents on phosphorus. 

The chemical differences between nitrogen and phosphorus are apparent in their elemental forms. In contrast to the diatomic form of elemental nitrogen, which is stabilized by strong tt bonds, there are several solid forms of phosphorus that all contain aggregates of atoms. White phosphorus, which contains discrete tetrahedral P4 molecules [see Fig. 20.18(a)], is very reactive it bursts into flames on contact with air (it is said to be pyrophoric). Consequently, white phosphorus is commonly stored under water. White phosphorus is quite toxic the P4 molecules are very damaging to tissue, particularly the cartilage and bones of the nose and jaw. The much less reactive forms, called black phosphorus and red phosphorus, are network solids (see Section 10.5). Black phosphorus 

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Phosphine is analogous to ammonia, although it is a much weaker base [K, == 10 ) and is much less soluble in water. 

When tetraphosphorus decoxide dissolves in water, phosphoric acid (EI3PO4), also called orthophosphoric acid, is produced  

An azeotrope is a solution that, like a pure liquid, distills at a constant temperature without a change in composition. 

In the second step, nitric oxide is reacted with oxygen to produce nitrogen dioxide  

This oxidation reaction has a rate that decreases with increasing temperature. Because of this very unusual behavior, the reaction is carried out at approximately 25°C and is kept at this temperature by cooUng with water. 

The third step in the Ostwald process is the absorption of nitrogen dioxide by water 

Nitric acid is a colorless, fuming liquid (bp = 83°C) with a pungent odor it decomposes in sunlight by the following reaction  

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This review concerns in the first part the works published during the last three years on the synthesis and reactivity of stabilized ylides C-substituted by electron-withdrawing groups (COR, CO2R, CN, etc.). The second part deals with the works published in the same period on the chemistry of phosphorus ylides mainly C-substituted by heteroatoms of groups 1-16 (metals, metalloids and nonmetal elements Li, Ba, Ca, Ti, Zr, Nb, Mo, Re, Fe, Ru, Rh, Pd, Pt, Au, Zn, Hg, B, Si, Sn, N, P, As, Sb, O, S, Te). 

P. B. Tinker, The chemistry of phosphorus and mycorrhizal effects on plant growth, Endoinycorrhizas (F. S. Saunders, B. Mosse, and P. B. Tinker, eds.). Academic Press, London, 1975, p. 353. 

Recent work in the chemistry of phosphorus heterocycles derived from a-hydroxyalkylphosphines and vinylphosphines, much of which has appeared in the Russian language literature, is covered by B. A. Arbuzov and G. N. Nikonov (Kazan, Russia). 

Although there exists a good understanding of the chemistry of phosphorus in soil-water systems, the hydrologic pathways linking spatially variable phosphorus sources, sinks, temporary storages, and transport processes in landscapes are less... 

Coates, H. The chemistry of phosphorus insecticides. Am. Appl. Biol, 36 156-159, 1949. 

The chemistry of phosphorus compounds with a delocalized P-C double bond proves to be very versatile. Whereas the physical properties of phosphamethin-cyanines are similar to the corresponding methin- or azamethin-cyanines, their chemical properties are distinguished by the higher reactivity of the phosphorus atom and the phosphorus-carbon double bond. 

J. Emsley and D. Hall, The Chemistry of Phosphorus, Wiley, Chichester, 1976. 

In this account we restrict the definition of phosphoranes to systems where five ligands are bonded to the phosphorus atom. Physical methods such as electron diffraction, X-ray analysis and low-temperature NMR of 31P, H, 13C and 19F are the most important aids in the study of phosphoranes, which are one of the most fascinating systems in the chemistry of phosphorus. 

The chemistry of phosphorus and sulfur is considerably more complicated than phosphorus-oxygen chemistry.)13 Only two phosphorus sulfides. P4SinaiK) P4S, are isoelectronic and isostruclural with phosphorus oxides. The former may be prepared by allowing stoichiometric amounts of phosphorus and sulfur to react ... 

The chemistry of phosphorus compounds was reviewed with particular attention to dipole moments235,236. Compounds with a C=P bond present the same problems as the C=N bond of course the number of derivatives is restricted and difficulties may arise with their stability. The simplest compound CH2=PH was investigated by MW in the gas phase237. From its dipole moment, 0.896 D, the P=C bond moment of 0.02 D was deduced238, which however was based on different bond moments than used here. In any case this bond is only slightly polar. 

The chemistry of phosphorus compounds has shown a steady development in the last 30 years. The most interesting results can be related to those systems having 7t-elec-trons in the broadest sense. Recent books [1-3] and review papers [4,5] have appeared on the topic. Particularly noteworthy is the statement summarized by the title of the Mathey-Nixon-Dillon book Phosphorus The Carbon Copy [2], which emphasizes the analogy between compounds of multiply bonded dicoordinate phosphorus (r>v. -P, this notation has been used in [1]) and the unsaturated carbon (see Scheme 1). 

Phosphorus is directly below nitrogen in the periodic table. (The relationship of the chemistry of phosphorus to that of nitrogen is somewhat like the sulfur-oxygen relationship discussed in the introduction to Chapter 17.) The phosphorus atom electron configuration is Ne 3.s,23/J3, and it has five outer-shell electrons, as shown by its Lewis symbol in Figure 18.1. Because of the availability of underlying 3d orbitals, the valence shell of phosphorus can be expanded to more than eight electrons. 

If additional information on the chemistry of phosphorus is desired, two books, the first of which is authored by Goldwhite (1981) and the second of which is edited by Quin and Verkade (1981), are recommended reading. 

The product of this reaction, P °, was the first man-made radioactive isotope reported and also the first positron emitter. By tracing the radiations, it could be shown that the positron-emitter produced in the reaction had the chemistry of phosphorus. In this case, then, the heavier product could be identified by its chemistry even though only very tiny amounts were formed. 

Although all of the elements are important and are found in many common compounds, phosphorus and its compounds are among the most useful and essential of any element. Consequently, the chemistry of phosphorus is considerably more extensive, and it is covered in greater detail. Much of the chemistry of the other elements can be inferred from their greater metallic character and by comparisons to the analogous phosphorus compounds. 

The oxo acids and anions in both lower and higher states are a very important part of the chemistry of phosphorus and arsenic and comprise the only real aqueous chemistry of these elements. For the more metallic antimony and bismuth, oxo anion formation is less pronounced, and for bismuth only ill-defined bismuthates exist. 

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