Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Sleepy on August 17, 2005, 04:40:43 PM
-
How can you tell this is a tetrahedral? Cis- [Co(en)2 Cl2]+
And that it is a optical isomer
-
i am not sure what the cpd is exaclty ??? (+)-Cis-Co2Cl2
so Cl Cl
\ /
Co--Co
this is what I am seeing with the Cis-isomer. To be tetrahedral, Co would need two lone pairs of electrons. Which I believe it does. So it would look something like below. where : and .. are lone pairs.
Cl Cl
\ /
: --Co--Co-- :
/ \
.. ..
The tetrahedral is formed between the Two Co's and one Cl and two lone pairs like this:
Cl
/
Co--Co-- : with all angles 120 degrees.
\
..
The (+) if at the beginning of the name means it rotates ( I think + is clockwise) in polarized light.
I hope i did this right, cause I'm not sure about the cpd. But you can also use HyperChem on the computers to find symmetry or structure. I am not at home so I can't use HyperChem right now.
Hope this helps...and hope its right. :)
-
The complex is octahedral like all those of trivalent cobalt, not tetrahedral. Octahedral complexes are chiral (have optical isomers) if they contain three chelate rings as in [Co(oxalate)3]3-; or if there are two rings and the remaining groups are cis, as in cis [Co(ethylenediamine)2Cl2]+. If you build models this will become clear. Trans [Co(ethylenediamine)2Cl2]+ has both chelate rings in the same plane, therefore has a plane of symmetry and is not chiral.
-
The complex is octahedral like all those of trivalent cobalt, not tetrahedral. Octahedral complexes are chiral (have optical isomers) if they contain three chelate rings as in [Co(oxalate)3]3-; or if there are two rings and the remaining groups are cis, as in cis [Co(ethylenediamine)2Cl2]+. If you build models this will become clear. Trans [Co(ethylenediamine)2Cl2]+ has both chelate rings in the same plane, therefore has a plane of symmetry and is not chiral.
so is Cis-[Co(ethylenediamine)2Cl2]+ the actual cpd.....boy it really helps to know what it is I was going to try and explain . :)
-
For trans-isomer exchange one NH2-group and Cl. Both Cl and Both NH2 groups are in the plane. For enantiomer exchange NH2 groups in plane. +1 charge is missing at Co!