TM charge

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bonnie_schmitz_1F
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TM charge

Postby bonnie_schmitz_1F » Wed Nov 28, 2018 1:13 pm

In class today, we saw how the nickel in [Ni (NH3)4 Cl] Cl 2 H2O had a charge of positive 2. I understand that the charge of +2 comes from the -1 charge on both of the Chlorine atoms, but how does the chlorine outside of the coordination compound affect the charge of the TM? Are the compounds outside of the coordination compound also bound to the TM?

daisyjimenezt
Posts: 30
Joined: Fri Sep 28, 2018 12:26 am

Re: TM charge

Postby daisyjimenezt » Wed Nov 28, 2018 2:38 pm

bonnie_schmitz_3K wrote:In class today, we saw how the nickel in [Ni (NH3)4 Cl] Cl 2 H2O had a charge of positive 2. I understand that the charge of +2 comes from the -1 charge on both of the Chlorine atoms, but how does the chlorine outside of the coordination compound affect the charge of the TM? Are the compounds outside of the coordination compound also bound to the TM?

I have the same question and also, the CL is outside the coordination sphere so why does it affect any charge

Ray Guo 4C
Posts: 90
Joined: Fri Sep 28, 2018 12:15 am

Re: TM charge

Postby Ray Guo 4C » Wed Nov 28, 2018 2:39 pm

Yes, the chlorine ions are bound to the metal. The metal forms ionic bonds with chlorine ions and coordinate covalent bonds with ligands. You can consider this as adding a few ligands to an ionic compound.

Sam Kelly 1K
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Joined: Fri Sep 28, 2018 12:16 am

Re: TM charge

Postby Sam Kelly 1K » Wed Nov 28, 2018 2:47 pm

One way to think of it is by looking at the coordination compound, [Ni(NH3)4 Cl] Cl . 2H2O in this case, as a more complex version of something like HCl, where the H is replaced by the the [Ni(NH3)4 Cl] complex. I'm not exactly sure about the relationship between the complex and the Cl outside of the brackets, but I think it's similar to something like [NH4+]Cl-, which is connected by an ionic bond

Matthew Tran 1H
Posts: 165
Joined: Fri Sep 28, 2018 12:16 am

Re: TM charge

Postby Matthew Tran 1H » Wed Nov 28, 2018 7:34 pm

The chloride ion inside the brackets are part of the coordination sphere while the chloride ion outside the brackets is not. The reason why we use the brackets is to show which ions/ligands are bonded to the transition metal. I agree with Sam here; the coordination compound and the chloride ion have an ionic bond. We can use this to determine the oxidation number of Ni. Since we know the chloride ion has a -1 charge, due to the ionic bond, the overall charge of the coordination compound it +1. Looking inside the brackets, chloride has a -1 charge and ammonia is neutral so in order for the coordination compound to have an overall charge of +1, Ni must have a +2 charge or oxidation number.


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