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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

What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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waht is hydrating power of lithium carbonates
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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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