Metallic and Metalloid Compounds

Metals may become locked up in the bottom sediments of aquatic systems by chemical reactions, where they may remain for many years. However, metal solubility increases if the pH falls and they become more mobile. In fact, one of the knock-on effects of acid rain is the transport of metals to lower levels in the soil profile, where they may damage deep-rooted plants and contaminate groundwater. A 

In addition to health concerns, the presence of metal ions in water can bring about side effects such as bad taste, increase in turbidity and coloration, staining of fixtures in contact with water, and the like. Iron and manganese ions may also promote bacterial growth with its concomitant drawbacks (e.g., foul smell). Fortunately many methods of treatment are available, as discussed in Chapter 10. 

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S. Clark A new method for the analysis of metal and metalloidal compounds , Thesis, Leicester Polytechnic, 1988, pp. 204-206. 

Oxidation of sulfur entities of metal sulfides to obtain energy is an example of direct dissolving action under aerobic conditions (Kurek, 2002). When oxidized metal compounds [e.g., Fe(III), Mn(IV), As(V)] act as electron acceptors, anaerobic respiration becomes an example of direct dissolving action under anaerobic conditions (Ahmann et al., 1994 Ehrlich, 2002). Volatilization of metals and metalloids or biomethylated metals and metalloid compounds from the soil into the atmosphere can be a mechanism of detoxification of toxic elements such as Hg, As, and Se for microorganisms (Gadd, 1993). 

The other major group of binary metal and metalloid compounds to be gas chromatographed at normal temperatures is that of halides. The major practical difficulty for these compounds often lies in their high reactivity and extensive precautions have to be taken to ensure maximum inertness of the whole chromatographic and sample handling system. In particular, care must be exercised to avoid hydrolysis during injection. 

While the existence of stable M—C bonds has long been regarded as a normal part of the chemistry of the non-transition metals and metalloids, compounds containing transition metal-to-carbon a bonds have only in recent years been made in substantial numbers. The reasons for the relative rarity of such compounds are still a subject for investigation, but several points seem clear. First, an important pathway for decomposition of M—R bonds is by a shift of a / -hydrogen atom, followed by olefin elimination, viz. H... 

Feld MANN J, Grumping R and Hirner AV (1994) Determination of volatile metal and metalloid compounds in gases from domestic waste deposits with GC/ICP-MS. Fresenius J Anal Chem 350 228-234. 

Biosorption is the process of removing metals and metalloid compounds and particulates from a solution using dead or alive biomass and cellular products (e.g. polysaccharides). In... 

Atomic emission spectral detection of metallic elements in GC shows something of an irony while detection limits and selectivities are usually better than for non-metals, because of greater emission intensities and absence of background interferences in the spectral region monitored, GC applications for metallic compounds in general are less common than for non-metals. However, many volatile binary metal and metalloid compounds, organometallic and metal chelate compounds can be quantitatively gas chromatographed [1], and some of the possible GC-... 

Metals and metalloids that form alkyl compounds, eg, methylmercury and methylarsenic acid, tributjltin, deserve special concern because these compounds are volatile and accumulate in cells they are poisonous to the central nervous system of higher organisms. Because methylmercury or other metal alkyls may be produced at a rate faster than it is degraded by other organisms, it may accumulate in higher organisms such as fish. Hg species are also reduced to elementary Hg which is soluble in water but lost by volatilization to the atmosphere (40). 

Azoles can form stable compounds in which metallic and metalloid atoms are linked to nitrogen. For example, pyrazoles and imidazoles Af-substituted by B, Si, P and Hg groups are made in this way. Imidazoles with a free NH group can be Af-trimethylsilylated and Af-cyanated (with cyanogen bromide). Imidazoles of low basicity can be Af-nitrated. 

Substances which have an adverse effect on the oxygen balance, particularly ammonia, nitrates The following metalloids and metals and their compounds ... 

A quite surprising development, even to experienced workers in elemental-fluorine chemistry, has been the synthesis of trifluoromethyl organometallic compounds by direct fluorination of metal alkyls (25). Even more surprising is the fact that, for certain metal and metalloid systems, such as the reaction of elemental fluorine with tetramethyl-germane, this t5rpe of low-temperature synthesis is a practical method 26) for the laboratory preparation of the perfluoro analog. 

Infrared Intensities of Metal Carbonyl Stretching Vibrations, 10, 199 Infrared and Raman Studies of w-Complexes, 1, 239 Insertion Reactions of Compounds of Metals and Metalloids, 5, 225 Insertion Reactions of Transition Metal-Carbon o-Bonded Compounds I Carbon Monoxide Insertion, 11, 88... 

Parts 1 through 5 of this chapter provide an outline of the reactions involved in the biodegradation of aliphatic esters, ethers, nitramines, phosphonates and sulfonates, and organic compounds of metals and metalloids. 

PART 5 DEGRADATION OF ORGANIC COMPOUNDS OF METALS AND METALLOIDS... 

Although knowledge on the biodegradation of these compounds is sparse, a number of them are important in industrial processes. Formation of methylated derivatives may take place in metals and metalloids belonging to groups 15 and 16 of the periodic table, and a few of group 14. These have been discussed in a critical review (Thayer 2002) and in Chapter 3, Part 4, and they have been noted in the context of the bacterial resistance to metals and metalloids. Since carbon monoxide has been considered as an organic compound (Chapter 7, Part 1), it is consistent to make brief comments on metal carbonyls. 

There are distinct structural types of organic compounds containing metals and metalloids. The first contain covalent carbon-metal bonds and are strictly organometallic compounds, for example, the alkylated compounds of Hg, Sn and Pb, and of Li, Mg, and A1 (and formerly Hg), which have been extensively used in laboratory organic synthesis, and A1(C2H5)3 that is a component of the... 

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