Metalloids compounds

Metals may also be linked through an oxygen or nitrogen atom to form a stable metal complex without a carbon-metal bond. These include metal complexes of ethylenediamine tetraacetate (EDTA), diethylenetriamine pentaacetate (DTPA), or ethylenediamine tetramethylphosphonate (EDTMP). Metalloid compounds include antimonyl gluconate and bismuth salicylate. 

Since these structures are formed by filling the open spaces in the diamond and wurtzite structures, they have high atomic densities. This implies high valence electron densities and therefore considerable stability which is manifested by high melting points and elastic stiffnesses. They behave more like metal-metalloid compounds than like pure metals. That is, like covalent compounds embedded in metals. 

Also metal-metalloid compounds tend to retain their hardnesses as temper-atures become elevated. These compounds have been discussed in Chapter 10. 

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

Challenger, F., Higginbottom, C. and Ellis, L. (1933) The formation of organo-metalloidal compounds by microorganisms. Part I. Trimethylarsine and dimethylarsine. Journal of the Chemical Society, 95-101. 

Among possible methods available to accomplish the synthesis of an alkyl- or aryl-metal or -metalloid compound, organo-... 

K. Jones and E. F. Mooney FIuorine-19 Nuclear Magnetic Resonance Spectroscopy, pp. 261-421 (410), esp. pp. 340-369, Organometallic and metalloid compounds. 

Speciation studies have been focused on relatively few elements, mainly aluminum, antimony, arsenic, chromium, lead, mercury, selenium, and tin. The primary species of these elements studied with ICP-MS detection are presented in Table 3 and they include different oxidation states, alkylated metal and/or metalloid compounds, selenoaminoacids, and selenopeptides. In addition, applications in studies of the pharmacokinetics of metal-based drugs (Pt, V, Au), metalloporphyrins (Ni, V, Fe, etc.), heavy metals in phytochelatins (Cd, Cu, Zn, Hg, etc.) and in humic substances should be mentioned. 

Intramolecular coordination in organo-metal (metalloid) compounds... 

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. 

The Diels-Alder reactions of two-coordinate metalloid compounds and their A derivatives have been one of the most useful applications of these compounds for the synthesis of unsaturated heterobicyclic compounds. The two-coordinate heterocycles have the potential to react as dieno-philes or as dienes. As dienophiles, reaction across the M=C bond gives the possibility of synthesizing a range of fused-ring compounds. Thus dimethyl 2//-phosphole reacts with a diene to give... 

Intermetallic and metalloid compounds may also be preparedby methods other than those described in the preceding sections. However, these other processes have so far been used only in special cases, since the necessary conditions tend to limit their general applicability. 

Some intermetallic or metalloid compounds may also be obtained by high-temperature electrolysis of liquid melts of the corresponding metal compounds. Secondary reactions sometimes play an Important role in this case. This method, developed mainly by Andrieux and Dodero [7], has so far been used for borides (see p. 1798), silicides (see p. 1796 f.), phosphides, arsenides and carbides. 

W. Jeitschko, Structural Chemistry of Transition Metal-Metalloid Compounds, in MTP International Review of Science, Inorg. Chem., Series 2, Vol. 5, Butterworths, London, 1974, pp, 219-281. 

Addition to 1,1 -bis(trihalomethyl)-2,2-dicyanoethylenes by various metalloid compounds (59) has been reported. Again the HSAB principle is followed. 

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