# Ammonia is a strong or weak field ligand?

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## Main Question or Discussion Point

Ammonia is present in the spectrochemical series near the middle, just after water. Is it a strong field ligand, or a weak field ligand?

Also, take into consideration the complex $[Ni(NH_3)_4 Cl_2]$. Chloride ion is towards the left end of the spectrochemical series which means it is a weak field ligand. Will the complex be a high spin or a low spin one?

## Answers and Replies

TeethWhitener
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Also, take into consideration the complex [Ni(NH3)4Cl2][Ni(NH3)4Cl2][Ni(NH_3)_4 Cl_2]. Chloride ion is towards the left end of the spectrochemical series which means it is a weak field ligand. Will the complex be a high spin or a low spin one?
Draw out the d-orbital configurations for Ni(II) high spin and low spin. What do you notice?

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Draw out the d-orbital configurations for Ni(II) high spin and low spin. What do you notice?
Ni(II) has 8 electrons in its 3d-orbital.

For low-spin complex:
$t_{2g}: d_{xy}^2 \, d_{yz}^2 \, d_{xz}^2$
$e_g: d_{x^2-y^2}^2 \, d_{z^2}^0$

For high-spin complex:
$t_{2g}: d_{xy}^2 \, d_{yz}^2 \, d_{xz}^2$
$e_g: d_{x^2-y^1}^2 \, d_{z^2}^1$

What conclusion can I draw from these?

mjc123
Homework Helper
Not that high-spin Ni(II) has nine d electrons, certainly.

TeethWhitener
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Also remember Hund’s Rule.

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My mistake. Corrected ones:

For low-spin complex:
$t_{2g}: d_{xy}^2 \, d_{yz}^2 \, d_{xz}^2$
$e_g: d_{x^2-y^2}^1 \, d_{z^2}^1$

For high-spin complex:
$t_{2g}: d_{xy}^2 \, d_{yz}^2 \, d_{xz}^2$
$e_g: d_{x^2-y^1}^1 \, d_{z^2}^1$

Both are same. Understood. Thanks @TeethWhitener

What about the first question:

Ammonia is present in the spectrochemical series near the middle, just after water. Is it a strong field ligand, or a weak field ligand?

TeethWhitener