Questions tagged [symmetry]
The description of the symmetry present in molecules. Molecular symmetry is useful for explaining or predicting of a molecule's chemical properties.
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A and B irreducible representations?
In character tables, I know that A and B are one-dimensional irreducible representations, but what is the difference them?
And why do some character tables list them as A1/A2, B1/B2 and others have ...
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Is perovskite symmetric under exchange of A and B atoms?
A perovskite is any crystal with the general formula $\ce{ABX3}$ where if the $\ce{B}$ atoms form a cube, an $\ce{A}$ atom sits in its center and the $\ce{X}$ atoms sit between neighboring $\ce{B}$ ...
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Why doesn't 1,3-dichloro-2,4-dimethylcyclobutane have a plane of symmetry?
In (1R,2R,3S,4S)-1,3-dichloro-2,4-dimethylcyclobutane, are the blue lines not planes of symmetry?
My book says it has a centre of symmetry, but not a plane of symmetry. But if I took a cut ...
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Are there different types of symmetry? [duplicate]
What factor does the symmetry of a molecule play?
For example, I know water is asymmetric so does this therefore make water polar (I know in fact that is is)? It may sound ignorant due to my lack of ...
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Find moment of inertia around two axes of sulphur dioxide
Problem:
Find the moment of inertia for 2 axes of $\ce{SO2}$. The rotational constants are given in $\pu{MHz}$. The answer is required to be $10^{-46}\rm~ kg\cdot m^2$, 7 digit accuracy.
I ...
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Does an axis of symmetry determine chiralty?
What I've understood about chirality and elements of symmetry:
A molecule that is not superposable on its mirror image is said to be chiral.
Plane of symmetry:
An imaginary plane cutting a compound ...
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Why is 2-methyl-2,3-pentadiene achiral (allene)?
2-Methyl-2,3-pentadiene is achiral. Why?
Centre of symmetry
Plane of symmetry
C2 axis of symmetry
Centre and Plane of symmetry.
I've drawn the structure:
So far I've dealt ...
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Structure and Vibrational Spectroscopy
What are the irreducible representations of the C-O stretching modes in free CO, $\ce{[Fe(CO)5][Fe(CO)4]^2-}$?
I think Free CO irreducible representation is A2.
For $\ce{[Fe(CO)5]}$ irreducible ...
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Analysis of metal carbonyl bonding in Fe(CO)5 using molecular orbitals
I am really struggling with this question we have been set in class:
Metal-carbonyl bonding: Conceptionally, one can build up $\ce{[Fe(CO)5]}$ from the $\ce{Fe(CO)4}$ fragment plus free $\ce{CO}$ in ...
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Creating Molecular Orbital and Walsh Diagrams
Does anyone know of a good website to create your own MO and Walsh diagrams? Could you potentially make them on a software package such as excel?
Any advice on this would be greatly appreciated.
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Is there an example of a closed shell molecule with a permanent ground state magnetic dipole?
It seems that molecules of point group C$_{n}$ and C$_{nh}$ can in principle support a permanent magnetic dipole moment (Barron, 2004). However, I cannot think of any closed shell molecules that ...
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What is difference between T1g and T2g?
I know that the “$\mathrm{g}$” stands for symmetry of octahedral shape, but how are labels “1” and “2” given in $\mathrm{A_{1g}}$ and $\mathrm{A_{2g}}$ representations too…
Is it related to group ...
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Why does benzene have a D6h point group?
I understand the fact that the molecule has a principal axis of rotation of C6 however when following the point gorup flow chart why is the answer to the second question NO when it contains two C3 ...
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What kind of bonds can form between benzene and transition metals in π-complexes?
I'm trying to draw the six π-orbitals (3 bonding, which are filled, and 3 anti-bonding) of a benzene ring when it complexes with metal d-orbitals and which metal orbitals have the correct symmetry ($\...
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Why can anthracene, but not phenanthrene, take part in Diels–Alder reactions?
Both anthracene and phenanthrene seem to be structurally similar, with three aromatic rings. The middle rings in particular seem to be similarly activated towards cycloadditions.
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Jahn-Teller Distortions in Square Planar Complexes?
A Jahn-Teller distortion is predicted whenever a non-linear symmetric molecule has degenerate orbitals and has unequal electron occupation in those degenerate orbitals. Of course, this most often is ...
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Racemic compound widely available
Can racemic compounds be found at the local drug store non-prescription? Where might one be found most readily/cheaply? Only one chiral center is needed. More may actually be unhelpful. The purpose ...
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How derive g and u symmetry labels for orbitals?
When asked whether a molecule has an inversion center, we "invert" the coordinates of all atoms; i.e. move each atom from its position through the center of symmetry and to a new position equidistant ...
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Why does (2z²-x²-y², x²-y²) have -1 trace in the character table of Td for C3 rotation?
I'm trying to understand the irreducible rep for $(2z^2-x^2-y^2, x^2-y^2)$ in the $T_\mathrm{d}$ point group. Specifically, for $C_3$ rotations, a trace of $-1$ is listed in the character table for ...
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Symmetrize nearly symmetric molecule
In the overall good paper of Beruski et. al.,[1] an algorithm of how to symmetrize an "almost symmetric" molecule by symmetrizing the distance matrix is given for the example of Methane.
The ...
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How many peaks would there be in H1 NMR of ethene?
Since the bonds can't rotate, would there be 2 peaks? Likewise, how many peaks would there be in trans-but-2-ene and cis-but-2-ene?
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Orbital mixing in square planar D4h complexes
Consider a square planar $\ce{ML4}$ complex with $D_\mathrm{4h}$ symmetry. Which orbital should the $\mathrm{a_{1g}}$ SALC of the ligands mix with, $\mathrm{3d}_{z^2}$ or $\mathrm{4s}$? Both of those ...
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Are all molecular structures symmetric?
Are all molecular structure symmetric either in relation to a plane within itself or in relation to other molecules? Are there any completely asymmetrical structures when looking at molecular geometry?...
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Equivalent hydrogens in 2,3-dimethylbutane
So while calculating for the relative yield of monochlorination for 2,3-dimethylbutane, I was counting the primary hydrogens, I counted 6, but in fact it was 12. Why is it 12? How do you find ...
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Are molecules chiral if a rotation leads back to the same compound?
I understand that if you rotate a molecule and it has the same configuration as its enantiomer, then it is indeed the same compound as the enantiomer (meso), and hence is achiral (despite having ...
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Amplitudes and phases of transform of an image
I have recorded an image of a large macromolecule and after several types of image analysis, have obtained a rotationally averaged image, that is not quite perfect, but appears to show 6-fold symmetry....
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Does symmetry lower the energy of molecules?
Why does nature "prefer" symmetry? Why is symmetry energy-lowering? I keep hearing statements along the lines of this tossed around by chemists. Here are some examples:
https://physics.stackexchange....
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Equivalent points for 3 fold and 6 fold symmetry
In a crystal Lattice how to find the equivalent points for 3 fold and 6 fold symmetry?
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Why does symmetry have to be maintained in molecular orbitals?
Using the example of $\ce{XeF4}$:
What is the physical explanation enforcing the symmetry of the $\ce{1b_{1g}}$ orbital on the fluorine atoms? Why isn't the symmetry of a nonbonding orbital arbitrary?...
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Symmetry representations for acetonitrile (CH3CN)
Can anybody share the symmetry labels for acetonitrile ($\ce{CH3CN}$), please?
I mean to assign the symmetry labels to orbitals of acetonitrile
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Why are square planar coordination compounds with four different ligands optically inactive?
Why do square planar coordination compounds of type $\ce{[Mabcd]}$ not show optical activity, although they contain 4 different ligands (i.e. chiral central metal atom)?
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How to get the reducible representations of the B-B and the B-Cl bond of B2Cl4
I just can't seem to get the correct answer to this symmetry question in my book. "Introduction to molecular symmetry J.S.Ogden."
I am trying to find the reducible representations of both the $\ce{B-...
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Symmetry representations
I'm Having a real struggle trying to understand symmetry representations matrices and character tables. Is there anyone who would be kind enough to help me out here? I understand it is probably a ...
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Symmetry C3V For MeCl
Methyl chloride belongs to the $C_{3\mathrm{v}}$ point group. This is because it has a $C_3$ axis down the $\ce{Cl-C}$ bond.
However what I do not understand is how it has three vertical mirror ...
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General methods of Analysis for FTIR Results
What can we say about a molecule from the position and number of bands in FTIR spectrum. I know that the more symmetric a molecule is, the less number of bands it has. What else can we say, for ...
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How does B2Cl4 have two perpendicular c2' axes?
I have been looking at the symmetry of $\ce{B2Cl4}$ and was cannot understand how it has two perpendicular $C_2'$ axes?
I understand it has a $C_2(z)$, $S_4(z)$ and two dihedral planes bisecting ...
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Finding the irreducible representation which an orbital transforms under [duplicate]
I have some major confusion on irreducible representations. An example of a problem I have is
Based on the character table for the point group of each of the follwing molecules, which irreducible ...
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What are t2g and eg in CFT?
In the crystal field theory (CFT), when the splitting of the d-orbital occurs, it gets divided into two parts.
The upper part with higher energy is the $\mathrm{e_g}$ and the lower part with lower ...
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Accessible statement on the intuition and usefulness of group theory to chemistry
I am writing a lesson plan for high school students who are studying group theory,
and I am having difficulty in relating the subject matter to the real world.
I have quite a few examples using the ...
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How can I find the symmetry labels of atomic orbitals in a molecule?
What are the symmetry labels for the p and d orbitals of platinum in $\ce{[PtCl4]^2-}$?
I understand how to find the point group of a molecule, but am not sure how to use the character table to find ...
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When is it true that more nodes equals higher energy?
Consider all the MOs of some isolated molecule. (It could be a single
atom too; I'll use MO to refer to AOs as well.) Number them in
increasing order of the number of nodes (node = surface where the ...
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Dipole moment of symmetrical molecules
While studying dipole moment in organic chemistry, I got stuck at a particular statement written in the book :
Symmetrical molecules without lone pairs of electrons will have $\mu = 0.$
The main ...
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An example to illustrate the difference between an inversion operation and a twofold rotation
Reading in Atkin's Inorganic Chemistry book, I cam accross:
Although an inversion and a twofold rotation may sometimes achieve the
same effect, that is not the case in general and the two ...
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Determining the lowest rank non-vanishing multipole moment [closed]
I have been told that the multipole moments of rank 0,1,2,3,...n have respectively 1,3,5,7,...2n+1 components which transform like the spherical harmonics of rank 0,1,2,3,...n. How do I use the ...
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Symmetry and stability of a molecule (Jahn-Teller Distortion)
I've taught in my class that if a molecule posses high degree of symmetry it's stability will be more,in other words symmetry and stability are directly proportional. Is this statement correct? And if ...
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Molecular chirality and optical rotation
Why does having molecular chirality result in optical rotation? The dissymetry or chirality of molecules translates to the rotation of plane polarized light, the magnitude and direction depending on ...
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Group Theory and Chemistry for Undergraduate Thesis
I am advising a student on her senior math thesis. She would like to involve chemistry somehow (her other major). I know no chemistry. I have read in several places that representation theory ...
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How do I determine the crystal field splitting for an arbitrary point group?
How can I figure out the degeneracy of the d orbitals for a site that has a given point group? Specifically I'm interested in $D_{3d}$ and $D_{3h}$, but it would be good to know how to do it in the ...
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Are chiral quasicrystals possible?
Quasicrystals are materials that have long-range atomic order but lack the translational symmetry of conventional crystals. All quasicrystalline tilings and packings I have read about thus far, whilst ...
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Are all cubic point groups encountered?
My symmetry lecture notes state that there are seven high-symmetry 3D point groups, which have more than one rotation axis of order greater than 2: $T$, $T_d$, $T_h$, $O$, $O_h$, $I$, $I_h$. I ...
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