✔ 最佳答案
Is there a typo?
Is it (NPCl2)3 or anything else instead?
2012-02-12 17:29:55 補充：
For (NPCl2)3, its structure is as follow :
圖片參考：
http://imgcld.yimg.com/8/n/HA00656648/o/701202080086113873435680.jpg
It can be found on wiki.
It is a trimer of NPCl2.
To deduce the structure of these kinds of compounds(diimer/trimer/...),
we can first count the number of bonds that commonly can be formed by the atoms.
Use (NPCl2)3 as example,
Nitrogen: 3
Chlorine: 1
Phosphorus: 3
the one that forms most bonds is usually the center atom.
However, in this case, N and P is the same.
So, we can see the less common forms,
P sometimes can form 5 bonds while N cannot(because of the orbital stuff).
So, we would use P as the center atom.
Then, draw the easiest ones, Cl, first, we can have
圖片參考：
http://imgcld.yimg.com/8/n/HA00656648/o/701202080086113873435681.jpg
Next, we add N(no matter single bond or double bond because when repeating, it will be just the same)
We may have
圖片參考：
http://imgcld.yimg.com/8/n/HA00656648/o/701202080086113873435692.jpg
Last, repeat it.
The key is to find out the center atom and the number of bonds it forms.
As metioned above: use the atom that can form most bonds, normally, as the center atom.
("normally" means not to concern the special cases like Cl can form up to seven bonds in ClO4-/N can form up to four bonds in NO2+/etc.)
While encountering cases that there are same ones(P and N), determine the possibility of atoms to hybridize and form more bonds. But still "common" is very important, do not concern the extremities.
Ask if you don't understand!
