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Group 13 halides are used as synthons for their organometallic derivatives, [link] and [link] .

Lewis acid-base complexes

All of the trihalides are strong Lewis acids, and as such react with Lewis base compounds to form Lewis acid-base complexes, [link] . The extent of the equilibrium is dependant on the Lewis acidity of the trihalide and the basicity of the Lewis base. For example, with BCl 3 , oxygen donor ligands result in approximately 50:50 ratio of BCl 3 and BCl 3 L, while for nitrogen donor ligands the equilibrium is shifted to the formation of the complex.

The general structure of the Lewis acid-base complexes is such that the Group 13 element is close to tetrahedral ( [link] ). However, for aluminum and the heavier Group 13 elements, more than one ligand can coordinate ( [link] ) up to a maximum of six.

Molecular structure of a typical Group 13 metal trihalide Lewis acid-base complex: AlBr 3 (9-fluorenone). Adapted from C. S. Branch, S. G. Bott, and A. R. Barron, J. Organomet. Chem ., 2003, 666 , 23.
Molecular structure of AlBr 3 (9-fluorenone) 2 . Adapted from C. S. Branch, S. G. Bott, and A. R. Barron, J. Organomet. Chem ., 2003, 666 , 23.

It should be noted that the dimeric form of MX 3 ( [link] ) can be thought of as mutual Lewis acid-base complexes, in which a Lewis basic lone pair of a halide on one MX 3 unit donates to the Lewis acidic metal on another MX 3 unit.


Generally the fluorides are insoluble in water while the heavier halides are more soluble. However, BF 3 , BCl 3 , and BBr 3 all decompose in the presence of water, [link] . In the case of the fluoride, the HF formed reacts with BF 3 to form fluoroboric acid, [link] . However, there is also a minor equilibrium (2-3%) resulting in the formation of the BF 3 complex of OH - and H 3 O + , [link] .

While the boron compounds (and AlBr 3 ) decompose even in moist air, AlCl 3 reacts more slowly to make aluminum chlorohydrate (ACH) which has the general formula Al n Cl 3n-m (OH) m . While ACH has been proposed to exist as a number of cluster species, it is actually a range of nanoparticles.

ACH is also known as polyaluminum chloride (PAC). The latter name is often used in water purification, where ACH is preferred over alum derivatives (Al 2 (SO 4 ) 3 ). The combination of ACH and a high molecular weight quaternized ammonium polymer (e.g., dially dimethyl ammonium chloride (DADMAC)), has been known as an effective combination as a flocculant in water treatment process to remove dissolved organic matter and colloidal particles present in suspension.

Aluminum chlorohydrate (ACH) and aluminum-zirconium compounds, are frequently used as the active ingredient in antiperspirants. The mode of action of most aluminum-based compounds involves the dramatic change in the particle size from nano to micro as a function of pH and electrolyte changes on the skin (as compared to the antiperspirant stick or suspension) and hence forming a gel plug in the duct of the sweat gland. The plugs prevent the gland from excreting liquid and are removed over time by the natural sloughing of the skin. A further mechanism of action involves the absorption of 3-methyl-2-hexenoic acid ( [link] ). Human perspiration is odorless until bacteria ferment it. Bacteria thrive in hot, humid environments such as the underarm. When adult armpits are washed with alkaline pH soaps, the skin loses its acid mantel (pH = 4.5 - 6), raising the skin pH and disrupting the skin barrier. The bacteria thrive in the basic environment, and feed on the sweat from the apocrine glands and on dead skin and hair cells, releasing 3-methyl-2-hexenoic acid, which is the primary cause of body odor. As with all carboxylic acids, 3-methyl-2-hexenoic acid, reacts in a facile manner with the surface of the alumina nanoparticles. Aluminum chloride salts also have a slight astringent effect on the pores; causing them to contract, further preventing sweat from reaching the surface of the skin.

Questions & Answers

can someone help me with some logarithmic and exponential equations.
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it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
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oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
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The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
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Differences Between Laspeyres and Paasche Indices
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No. 7x -4y is simplified from 4x + (3y + 3x) -7y
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. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
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Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
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In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
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Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
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Source:  OpenStax, Chemistry of the main group elements. OpenStax CNX. Aug 20, 2010 Download for free at http://cnx.org/content/col11124/1.25
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