Arsenic compounds structural information

In chemical combination, arsenic can exist in oxidation state III or V and can have a coordination number of 3, 4, 5, or 6. In marine samples, arsenic is mainly found in the V oxidation state, although, usually as a consequence of biological factors, arsenic (III) compounds can also occur and may at times be predominant. The properties and analysis of the various arsenic-containing compounds of significance in marine arsenic research are briefly discussed, and information is provided on their synthesis. For ease of reference, the arsenic compounds frequently mentioned by name (or abbreviation/acronym) are listed in Table IV together with their structure numbers. 

It might be thought that the vibrational analysis for PC1 F5 was redundant, since the electron diffraction data provided complete structural information. This is not quite true the two studies were in fact complementary. In the radial distribution functions obtained from electron diffraction, some of the peaks were ill-resolved their better resolution in order to obtain accurate structural parameters was assisted by the amplitudes of vibration which can be calculated by normal coordinate analysis. The vibrational study was also valuable when, in 1987, the same team tackled the structural characterisation of the analogous arsenic compounds. These presented some experimental difficulties, because they are thermally less stable than their phosphorus analogues they tend to decompose to give As(III) species, e.g. 

The identification of arsenic compounds using element-specific detectors in general is based on matching the retention time with known standards. This works perfectly as long as known standards are available. When unknown signals are obtained in a chromatogram, ICP-MS cannot provide any structural information and other detectors must be applied. 

Resonance (ESR). The effects of radiation on arsenic, antimony and bismuth compounds are, however, considerably less documented a compilation of the corresponding information has been published in Landolt-Bomstein and this subject is periodically reviewed in Specialist Reports of the Royal Chemical Society. The purpose of this chapter is not to present an exhaustive compilation of all the species produced by radiolysis of organic compounds which contain an As, Sb or Bi atom, but only to deal with the most important types of radiogenic radicals formed from these compounds and, when possible, to compare the structures of these radicals with those of the corresponding phosphorous species. 

This review expands on the chapter by Atkinson in the first edition of Comprehensive Heterocyclic Chemistry (CHEC-I) <84CHEC-I(l)539> by detailing certain areas and highlighting the higher coordination states available to arsenic, antimony, and bismuth. Some new topics, such as the 1,1 -biheteroles and coordination compounds, are added. Experimental structural methods and thermodynamic aspects are expanded and include new information. 

There are many common features to the structural chemistry of rare earth compounds formed by the tetrahedral oxoanions RXO4, where X is a pentavalent element (P, As, V, Cr). Nevertheless, considerably less structural and other information is available for the rare earth arsenates than for the phosphates and vanadates. 

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