Mercury-phosphorus coupling

Analyses of P NMR spectra of solid [HgPCy3(OAc)2]2 performed by Bryce and co-workers provided a new experimental value of AVpHg, 4700 300 Hz, indicative of anisotropy in the indirect nuclear mercury-phosphorus coupling arising due to non-Fermi contact contributions to /. This result is within the known range of A /pHg values. 

Table 13. One-bond mercury—phosphorus coupling constant...

Phosphoryl radicals [10, 18, 38-42] tend to add to double bonds. Owing to the exceptionally high constants of hyperfine coupling of the unpaired electron with the phosphorus nucleus, phosphoryl radicals can be utilized as paramagnetic reporters [10]. Phosphoryl radicals have been prepared by photolysis of diphosphoryl mercury compounds (Scheme 6.5). 

The reducing agents usually employed are phosphorus and hydriodic acid, or the zinc-copper or the aluminium-mercury couple. The couples have the advantage of readily yielding a pure gas, and are of wide application. 

In the case of aromatic bodies the temperature has an important influence on the part of the molecules the chlorine or bromine will attack in the cold in the presence of carriers, the halogen enters the nucleus, while at the boiling point the side chain is attacked. The carriers most frequently used are iron, aluminium-mercury couple, iodine, halides of phosphorus, antimony, iron, aluminium, sulphur or pyridine. The halogen is always more active in sunlight, or in ultra-violet light. 

The substantially larger values of M-p for phosphorus trans to chlorine compared with phosphorus trans to phosphorus correlate with shorter M-P bonds trans to chlorine for a number of metals and oxidation states tungsten(IV), rhodium(I) and (III), platinum(II) and (IV), and linear mercury(II) (15). By analogy with the discussion of the results for the platinum(II) complexes, this indicates the dominance of the (P sMSp)2 term in Equation 1 for couplings with a variety of M, but as discussed earlier it is difficult to determine the extent of variation of... 

A combination of IPC and inductively coupled plasma (ICP) MS was extensively explored for the speciation of phosphorus, arsenic, selenium, cadmium, mercury, and chromium compounds [108-118] because it provides specific and sensitive element detection. Selenium IPC speciation was joined to atomic fluorescent spectrometry via an interface in which all selenium species were reduced by thiourea before conventional hydride generation [119], Coupling IPC separation of monomethyl and mercuric Hg in biotic samples by formation of their thiourea complexes with cold vapor generation and atomic fluorescence detection was successfully validated [120]. The coupling of IPC with atomic absorption spectrometry was also used for online speciation of Cr(III) and Cr(VI) [121] and arsenic compounds employing hydride generation [122]. 

IPC-ICP-MS was extensively explored for the speciation of phosphorus, arsenic, selenium, cadmium, mercury, and chromium compounds [4-17] because it provides specific and sensitive element detection. Selenium IPC speciation took also advantage of coupling with atomic fluorescent spectrometry via an interface in which all selenium species are reduced by thiourea before conventional hydride generation... 

For chlorination in the liquid phase, chlorine gas is led into the liquid and is dispersed in the form of fine bubbles. In most chlorina-tions heat and a catalyst are employed. Phosphorus and its halides, sulfur and its halides, iron, aluminum chloride, antimony chloride, and iodine are among the common catalysts used for chlorinations. For laboratory use red phosphorus, iron, and thionyl chloride give good results. Aluminum chloride (or aluminum-mercury couple), although a very efficient catalyst, clogs the disperser. The use of actinic light is sometimes used to promote chlorination in the liquid phase, and is extensively used in the vapor phase. The action of the catalysts is assumed to activate a few chlorine molecules which initiate chain reactions. For example, in the chlorination of benzene the reaction begins with the dissociation of a few molecules of chlorine to atoms ... 

Heavy metals, boron (B(V)), arsenic and total phosphorus were determined in the fraction < 20 pm to improve the comparability of the results. This fraction was separated from the freeze-dried and non-milled samples by ultrasonic sieving (Ackermann 1980). Metals were analysed after microwave-assisted digestion with aqua regia at 180 °C in closed vessels by inductively coupled plasma optical emission spectroscopy, atomic fluorescence spectroscopy (mercury) and hydride atomic absorption spectroscopy (arsenic). 

The ASTM F 1185 designation specifies chemical and crystallographic requirements for hydroxyapatite applied to the surfaces of surgical implants. Elemental analyses for calcium and phosphorus will confirm the expected stoichiometry of hydroxyapatite. The calcium and phosphorus contents will be determined by a suitable method such as ion chromatography. A quantitative X-ray diffraction analysis will determine a hydroxyapatite content of at least 95%. The concentration of deleterious trace elements such as arsenic, cadmium, mercury and lead will be assessed for hydroxyapatite derived from natural resources. The analysis of other trace elements may be required, based on the conditions, apparatus or environments specific to the manufacturing techniques and raw materials. Inductively coupled plasma/mass spectroscopy (ICP/MS), atomic absorption (AAS) or the... 

All major ash elements and some trace elements are determined in coal or fly ash by inductively coupled plasma emission spectrometry. Parr oxygen bomb combustion followed by ion selective electrode. X-ray fluorescence or atomic absorption spectrom-etric measurements are used to determine halogens, sulfur, nitrogen, mercury, arsenic, selenium, and phosphorus. Hydride generation-atomic absorption spectrometry is used to determine traces of As,... 

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