Phosphorus and Phosphines

Phosphorus and Phosphines.—Red phosphorus is transported, using a low-pressure hydrogen discharge, to give a product purer than the starting material, in amorphous layers. There is evidence for the suggestion that the transport mechanism involves the formation and subsequent decomposition of unstable volatile hydrides. Applications of a low-pressure silent electric discharge in 

calculations, both with and without d-orbital participation, have been reported for PHaF, PH3F2, PH5, PH4F, and PH2F3. PH4 radicals 

Problems associated with (p-d)Tr-bonding in four-co-ordinated phosphorus compounds, i.e. R3PX (R = H, Me, or Cl X = O, NH, BH3, S or CH2), have been approached by a comparison of the X-ray p.e. spectra of those species with those of the corresponding nitrogen compounds, and correlation with results from M.O. calculations. The overall conclusion is that there is little influence of d-orbitals on the bonding in these compounds. 

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Arbuzova, S.N., Gusarova, N.K., Malysheva, S.F., Brandsma, L., Albanov, A.I., and Trofimov, B.A., Reaction of red phosphorus with electrophiles in super-basic systems. Part 8. Reaction of red phosphorus and phosphine with aryl alkenes, Zh. Obshch. Khim., 66, 56, 1996. 

In a series of papers, metal sulfide cluster anions of first-row transition metals, principally copper, have been reacted with a variety of reagents including thiols, sulfur, phosphorus, and phosphines (99, 145, 256, 257). 

Analytical Methods for Determining Elemental Phosphorus and Phosphine in... 

Chemical Reactions.—P12H6 is dissociated when heated above 70° C-. in an indifferent gas—into its elements at 175° C. in CO 1 or into phosphorus and phosphine at 215° C. The ignition temperature in air is 120° to 150° C.1 The only liquids which dissolve it without decomposition are phosphorus and PaH4. It dissolves in ammonia at -40° C. with evolution of phosphine. After evaporation of the ammonia a black solid is left which appears to be an ammine of a higher hydrogen phosphide. Like the other phosphides it is easily oxidised by halogens, chlorates and nitric acid.2... 

Another important feature of phosphines is their use as chiral ligands. It is possible to make phosphines that are chiral at phosphorus, and phosphines that have achiral phosphorus atoms with chiral groups attached to them (Scheme 3). 

The clinical pictures of both phosphorus and phosphine poisoning are similar, despite the differing routes of intake. It has been intimated that phosphorus toxicity may be due to phosphine, and that phosphorus is converted to phosphine in the liver, or more probably that this reduction would occur via microbially-assisted metabolism within the gastrointestinal tract before absorption. Phosphine has been detected in the flatus of cows. However, although interesting, this merely avoids the issue and does not provide any further understanding of the molecular mechanisms of toxicity. 

Gusarova NK, Sukhov BG, Malysheva SF, Kazantseva Tl, Smetannikov YuV, Tarasova NP, Trofimov BA (2001) Reactions of elemental phosphorus and phosphines with electrophiles in superbasic systems XIII. phosphorylation of phenylacetylene with active modifications of elemental phosphorus. Russ J Gen Chem 71 721-723... 

Phosphorus is m the same group of the periodic table as nitrogen and tricoordi nate phosphorus compounds (phosphines) like amines are trigonal pyramidal Phos phmes however undergo pyramidal inversion much more slowly than amines and a number of optically active phosphines have been prepared... 

Although unsynunetrically substituted amines are chiral, the configuration is not stable because of rapid inversion at nitrogen. The activation energy for pyramidal inversion at phosphorus is much higher than at nitrogen, and many optically active phosphines have been prepared. The barrier to inversion is usually in the range of 30-3S kcal/mol so that enantiomerically pure phosphines are stable at room temperature but racemize by inversion at elevated tempeiatuies. Asymmetrically substituted tetracoordinate phosphorus compounds such as phosphonium salts and phosphine oxides are also chiral. Scheme 2.1 includes some examples of chiral phosphorus compounds. 

Whereas the barrier for pyramidal inversion is low for second-row elements, the heavier elements have much higher barriers to inversion. The preferred bonding angle at trivalent phosphorus and sulfur is about 100°, and thus a greater distortion is required to reach a planar transition state. Typical barriers for trisubstituted phosphines are BOSS kcal/mol, whereas for sulfoxides the barriers are about 35-45 kcal/mol. Many phosphines and sulfoxides have been isolated in enantiomerically enriched form, and they undergo racemization by pyramidal inversion only at high temperature. ... 

Speziale and his co-workers have carried out comprehensive studies of the reactions of phosphorus compounds. It has been shown 108) that the reaction of N,N-dialkyl-a-trichloroacetamides (127) with phosphites and phosphines gives trichlorovinylamines (128). In general the trialkyl-phosphines gave somewhat higher yields (60 to 83%) and purer products... 

The recommended names for these compounds (phosphinic acid and phosphinates) have not yet gained wide acceptance for inorganic compounds but are generally used for organophosphorus derivatives. Hypophosphites can be made by healing white phosphorus in aqueous alkali ... 

Besides the thiocyanates, just mentioned, other 5-donor complexes which are of interest are the dialkyl sulfides, [MCl3(SR2)3], produced by the action of SR2 on ethanolic RhCl3 or on [IrClg] ". Phosphorus and arsenic compounds are obtained in similar fashion, and the best known are the yellow to orange complexes, [ML3X3], (M = Rh, Ir X = Cl, Br, I L = trialkyl or triaryl phosphine or arsine). These compounds may exist as either mer or fac isomers, and these are normally distinguished by their proton nmr spectra (a distinction previously made by the measurement of dipole moments). An especially... 

Diphenyl-2-thienylphosphine is expected to serve as a bidentate ligand by coordination of either the phosphorus and sulfur atoms or the phosphorus atom and TT-electrons of the heteroring. Reaction of this phosphine with [Rc2(CO)lo] yields the species where both the sulfur and phosphorus atoms serve as the donor sites (960M786). 

The initial step of olefin formation is a nucleophilic addition of the negatively polarized ylide carbon center (see the resonance structure 1 above) to the carbonyl carbon center of an aldehyde or ketone. A betain 8 is thus formed, which can cyclize to give the oxaphosphetane 9 as an intermediate. The latter decomposes to yield a trisubstituted phosphine oxide 4—e.g. triphenylphosphine oxide (with R = Ph) and an alkene 3. The driving force for that reaction is the formation of the strong double bond between phosphorus and oxygen ... 

Phosphine oxides, e.g., di-/ -octadecylphosphine oxide, are oxidized to phos-phinic acids by hydrogen peroxide. With chlorine or phosphorus pentachloride, phosphine oxides form dialkylphosphinyl chlorides, R2P(0)C1, which can be easily hydrolyzed to phosphinic acids [162,165] see Eqs. (96) and (97) ... 

A comparison of bromine and phosphorus compounds on the flammability of PET fiber shows phosphorus (as phosphine oxide) to be 3.7 times more effective than bromine (Table 1). No synergy was observed. Nevertheless, phosphorus was shown to be more effective than antimony normally used as a synergist, resulting in a higher oxygen index at a lower concentration (Table 2). 

A cluster with five Au atoms exists in Au5(dppm)3[(Ph2P)2CH]KN03)2. This cluster has a AU4 core, with an additional Au incorporated in the phosphine ligand, linearly coordinated between a phosphorus and a carbon from the methanido bridge (IV) ... 

The stability of phosphinous amides depends, to a large extent, on the substituents at phosphorus and nitrogen. Normally, tetrasubstituted and N,P,P-trisubstituted phosphinous amides are stable and well-known compounds. The parent compound H2PNH2 is a volatile compound that is formed on hydrolysis of a solid state solution mixture of magnesium phosphide and magnesium... 

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