All Questions
Tagged with symmetry molecular-structure
23
questions
-2
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0
answers
40
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Are all helicenes optically active? Aren't they having a plane of symmetry? [closed]
Are all helicenes optically active?
Aren't they having a plane of symmetry or centre of symmetry?
Please give a detailed explanation
- 7
0
votes
0
answers
128
views
When does the angle between the planes in tetrahedral molecule with central atom deviate from 90°?
Consider an atom X bonded to four other atoms A, B, C, D in a tetrahedral fashion with sp³ hybridisation. If A, B, C, D are the same, every bond angle is 109.47°, and the angle between the planes ...
- 340
0
votes
1
answer
272
views
Of 2-bromobutan-2-ol and trans-1,2-dimethylcyclobutane which is chiral as well as dissymmetric?
In an examination I was asked to determine the molecules which are chiral as well as dissymmetric. There were four options, and among them, two were achiral, as they had an improper axis of symmetry. ...
- 371
12
votes
2
answers
4k
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How are there two C3 rotation axes in ammonia?
If we look at the character table for the $C_\mathrm{3v}$ point group (which $\ce{NH3}$ is an example of), we see that these are the symmetry elements ${E, 2 C_3, 3 \sigma_v}$ present in the molecule. ...
- 682
1
vote
0
answers
101
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$Q_3$ is symmetric with respect to the $\sigma_v$ operation?
I am currently studying the textbook Infrared and Raman Spectroscopy: Principles and Spectral Interpretation, second edition, by Peter J. Larkin. Section 8. Symmetry: Infrared and Raman Active ...
- 1,083
5
votes
1
answer
554
views
Is there a geometrically intuitive explanation of the equivalence of the numbers of irreducible representations and symmetry classes?
In group theory, as used in chemistry, we’re familiar with the idea that the number of irreducible representations of a symmetry group equals the number of classes of symmetry operations, e.g. three ...
- 223
4
votes
1
answer
554
views
Do we consider the spatial orientation of a molecular orbital while assigning plane of symmetry?
I am following the video lectures by Neeraj Saini sir and in this video$^{\dagger}$ he said that $\ce{CO2}$ has infinite planes of symmetry.
But I think that if we take into account the orientation of ...
user88957
7
votes
1
answer
5k
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In what way trans alkenes are more symmetric than cis alkenes?
While providing the reason for the higher melting point of trans molecules, everyone says that trans molecules are more symmetric than cis molecules. An example can be found over here, where the OP ...
user88957
1
vote
1
answer
863
views
Determine and draw planes and axes of symmetry of a molecule using software (VESTA or Mercury)
I designed the $\text{MoS}_2$ molecule (bilayer), with polytype 2H in the VESTA. My goal is to draw the plans and axes of symmetry of the bilayer set. According to the information in the literature, ...
- 203
0
votes
1
answer
560
views
Are there optically active molecules in which all atoms lie in the same plane?
I've learnt that when a molecule is non-superposable on its mirror image, it exists as a pair of enantiomers and is optically active. Absence of plane of symmetry is given to be one of the properties ...
- 2,080
6
votes
2
answers
636
views
Chromium cyanide complexes
I have rarely seen any chromium $(\ce{Cr})$ square planar complexes and I have been told that $\ce{[Cr(CN)4]-}$ is tetrahedral.
So, if the statement is actually correct, are there any other known ...
- 333
3
votes
1
answer
561
views
Number of stereoisomers of polysubstituted cubane
The molecule given below is a substituted cubane.
a) How many stereoisomers exist for this molecule?
b) How many pairs of enantiomers are possible?
How do I calculate the number of stereoisomers? ...
- 203
3
votes
1
answer
1k
views
AB5E type molecule
In $\ce{AB5E}$-type molecules, why are the lone pairs in axial bonds?
If the lone pair is present in axial bonds it repels four other bonds. On the other hand if the lone pair is in equatorial ...
- 226
2
votes
0
answers
132
views
Theory of symmetry breaking in water?
As we all know $\ce{H2O}$ is bent ($C_\mathrm{2v}$) in its ground state equilibrium structure, rather than linear ($D_\mathrm{\infty h}$), which can be readily understood e.g. from the MO diagram of ...
1
vote
1
answer
83
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Reading Stereographs
On an old paper, I found an interesting representation of some symmetry operations: stereographs.
Online I found a set of symmetry operations and related stereographs (see: http://newton.ex.ac.uk/...
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