bis and tris

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204301116
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Joined: Fri Sep 26, 2014 2:02 pm

bis and tris

Postby 204301116 » Wed Dec 10, 2014 12:04 am

How do you know when to use bis and tris as opposed to di, tri, tetra.. ?

Shreyesi Srivastava 2D
Posts: 11
Joined: Fri Sep 26, 2014 2:02 pm

Re: bis and tris

Postby Shreyesi Srivastava 2D » Wed Dec 10, 2014 12:17 am

You use bi and tri when the compound already has a di/tri type naming in it. For example, ethylenediamine already has di because it is referring to its two amine compounds; in this case, you would use bis if you had two of these. It would be called bisethylenediamine.

Helen Leka 1H
Posts: 10
Joined: Fri Sep 26, 2014 2:02 pm

Re: bis and tris

Postby Helen Leka 1H » Wed Dec 10, 2014 4:01 pm

Also, you would use bis, tris, etc when the compound is polydentate meaning it has more than on central atom. Monodentates like chlorine use the prefixes di, tri, tetra etc.

Elif Kesaf 3L
Posts: 2
Joined: Fri Sep 26, 2014 2:02 pm

Re: bis and tris

Postby Elif Kesaf 3L » Fri Dec 12, 2014 2:59 pm

There are two situations in which you use bis, tris, tetrakis etc.:

1) if the ligand already contains a Greek prefix
e.g. Ethylenediamine (en) has the Greek prefix "di". Therefore, when there are two molecules of ethylenediamine in a coordination compound, instead of saying diethylenediamine, you say bisethylenediamine.

2) when the ligand is a polydentate (able to attach at more than one binding site)
e.g. Again, ethylenediamine is a bidentate; it attaches the transition metal at two binding sites. Therefore, when there are two molecules of ethylenediamine in a coordination compound, we say bisethylenediamine, not diethylenediamine.

Some other polydentates are:
-oxalato (C2O42-) is bidentate
-edta is hexadentate

**Don't forget that water (H2O) is not polydentate; it is monodentate. Therefore, for water, you use di,tri, tetra..., NOT bis, tris, tetrakis...

Information source: textbook page 683 (Toolbox 16.1) For more information, refer to textbook page 683.


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