Sapling 5

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Karina Rodriguez 2H
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Joined: Wed Sep 30, 2020 9:34 pm

Sapling 5

Postby Karina Rodriguez 2H » Sun Dec 06, 2020 7:48 pm

Can anyone explain how to calculate the coordination number for [Co(en)2(CO)2]Br ? Also what does the (en) refer to?

Nathan Lao 2I
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Re: Sapling 5

Postby Nathan Lao 2I » Sun Dec 06, 2020 7:52 pm

Hi! En refers to the ethylenediamine ligand, C2H4(NH2)2, and is a bidentate ligand. This means that it will bond to the cobalt ion at two sites. Using this information, the two en ligands will make 4 bonds. Add the two CO bonds and you'll get a total of 6 bonds, or a coordination number of 6.

Xinyu Li 1C
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Re: Sapling 5

Postby Xinyu Li 1C » Sun Dec 06, 2020 7:53 pm

(en) refers to NH2CH2CH2NH2, or ethylenediamine. It's a bidentate ligand (coordination number=2). And chlorine is a monodentate ligand (coordination number=1). So together, the coordination number for [Co(en)2(CO)2]Br is 2*2+2*1=6.

Megan Lu 3D
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Re: Sapling 5

Postby Megan Lu 3D » Sun Dec 06, 2020 9:18 pm

Hi! Like others have explained above, (en) is the ethylenediamine ligand, or NH2CH2CH2NH2 (you can find this in Table 9C.1), which is a bidentate ligand.

To calculate the coordination number, we would consider the number of bonds that the metal (Co) can form with the ligands (en and CO). There are two en ligands, with each forming two bonds, and two CO ligands, with each forming one bond as a monodentate. Thus, we can do 2(2) + 2(1) = 6 total bonds, our coordination number. Hope this helps!

Andrew Yoon 3L
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Re: Sapling 5

Postby Andrew Yoon 3L » Sun Dec 06, 2020 10:06 pm

(en) refers to ethylenediamine ligand, or NH2CH2CH2NH2. Ethylenediamine ligand is a bidentate ligand which has a coordination number of 2, and since there are 2 of en, the coordination number would 4. For CO, since there are 2 of it, it will form one ligand each as a monodentate, which will have a coordination number of 2. So in total, the coordination number would be 6.

Thomas Gimeno
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Re: Sapling 5

Postby Thomas Gimeno » Sun Dec 06, 2020 10:21 pm

En is a ring and contributes 2 to the coordinate number. The cl2 contributes another two to the coordinate number so the total number is 4. This is because the coordinate number is just the number of atoms/molecules the central metal is bound to.

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Re: Sapling 5

Postby rhettfarmer-3H » Sun Dec 06, 2020 11:14 pm

yeah for sure, this question is a little tricky in the sense that you have to know you ligands. SO we have 2 different ligands en and we have two of them and we have two CO. For this problem it seems like oh there is simply a coordination number of 4 but wait. En is bidentate so we have to add 2 for each en. SO 4 from the two en and 2 for each monodentate CO. We get a coordination number of 6.

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