Phosphorus exchange

While the phosphorus exchange is 130 times faster than the antimony exchange for the same basic process the energies of activation (16 and 19 kcal.mole ) are similar. No light sensitivity was observed in the P exchange. 

This equatorial axial phosphorus exchange shows that in the most stable diastereoisomer, the phosphine is in the axial position while the phosphite, the best 7r-acceptor is located in the equatorial position. This behavior contrasts with the coordination mode found for the BINAPHOS in which the phosphine occupies the equatorial position and the phosphite the axial position. 

Figure 6.10 A Equatorial-apical phosphorus exchange. B Equatorial-equatorial phosphorus exchange. Reproduced from Ref. [39] with per-...

The synthesis of phospholes involving the oxidative coupling of dienes with zirconocenes followed by zirconium-phosphorus exchange upon addition of dihalogenophosphine (Fagan-Nugent method) has been used extensively in the last few years for the preparation of functionalized phospholes. For example, 1-chlorophospholes 162 and... 

Smith R. E., Harrison W. G., and Harris L. (1985) Phosphorus exchange in marine microplankton communities near Hawaii. Mar. Biol. 86, 75-84. 

Holm, N. G. (1978). Phosphorus exchange through the sediment-water interface Mechanism studies of dynamic processes in the Baltic Sea. Ph.D. thesis, Contr. in Microbial Geochemistry, Department of Geology, University of Stockholm. 

The synthesis of the parent compound is not possible by method 1. It is achieved by reaction of penta-l,4-diyne 17 with dibutyltin hydride forming stannacyclohexa-1,4-diene 18 by a cyclization/ addition sequence. Tin-phosphorus exchange by phosphorus tribromide converts 18 into dihydro-A -phosphinine 19 which, on dehydration with DBU (Ashe 1971), yields the phosphabenzene ... 

FIGURE 9.21 Schematic showing phosphorus exchange between solid phase and solution phase. (Modified from Froelich, 1988.)... 

PHOSPHORUS EXCHANGE BETWEEN SOIL AND OVERLYING WATER COLUMN... 

The processes affecting phosphorus exchange at the soil/sediment-water interface include... 

The energy barrier for the fluxional processes is lower when the steric bulkiness of the ortho substituent of the ligand decreased. The lowest energy barriers correspond to equatorial-axial phosphorus exchange in complexes containing seven-membered chelate rings. 

Figure 8. (A) Equatorial-axial phosphorus exchange. (B) Equatorial-equatorial pho horus...

Iridium. The F NMR spectrum of (58) shows two different CeFs groups at low temperature which exchange. Phosphorus exchange in [(dppm)Ir( = CFi2)(CO)] -I- has been studied. ... 

After bromination, two different procedures were tested for a bromine-phosphorus exchange. The first one is the Michaelis-Arbuzow reaction in the presence of transition metal salt catalysts [41,42] the second one is a P-C coupling reaction catalyzed by Pd (0) complexes [43-45]. Both reactions are usually carried out without any solvent. It was foimd that the reaction conditions of the P - C coupling reaction could be adapted to the application of polymeric substrates [65]. 

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