2. Draw the following molecules and ions and identify if they have (a) a centre of inversion and (b) an S4 axis. Show these symmetry elements as a point for (a) or a line for (b), where applicable. (i) CO₂, (ii) C₂H₂, (iii) BF3, (iv) SO4²-

2. Draw the following molecules and ions and identify if they have (a) a centre of inversion and (b) an S4 axis. Show these symmetry elements as a point for (a) or a line for (b), where applicable. (i) CO₂, (ii) C₂H₂, (iii) BF3, (iv) SO4²-

Organic Chemistry: A Guided Inquiry

2nd Edition

ISBN:9780618974122

Author:Andrei Straumanis

Publisher:Andrei Straumanis

ChapterL3: Carbon (13c) Nmr Spectroscopy

Section: Chapter Questions

Problem 1E

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Similar questions

Identify the symmetry elements present in the following objects. a The Eiffel Tower. You may have to look up a picture of it if you dont remember its shape b Any book ignore the printing. c An octagonal wood block. d A jack from the set of jacks pictured here: Note that some of the points end differently.
In your own words, explain why an object that has more symmetry elements is said to have higher symmetry than an object with fewer symmetry elements.
3
List the symmetry elements of the following molecules and name the point groups to which they belong: (a) staggered CH3CH3, (b) chair and boat cyclohexane, (c) B2H6, (d) [Co(en)3]3+, where en is 1,2-diaminoethane (ignore its detailed structure), (e) crown-shaped S8. Which of these molecules can be (i) polar, (ii) chiral?
Neopentane, C(CH3)4, has Tď symmetry, with character table provided below. Suppose the characters of a reducible representation of this point group are x(E) = 17, x(C3) = 2, x(C₂) = 5, x(S4) = -3, and x(od) = -5 (this is shown explicitly in the last row of the character table). (a) Use the T₁ irreducible representation to determine the order of the point group using the Little Orthogonality Theorem (Vallance Eq. 1.15.13, see Problem 3). (b) Determine how many times each irreducible representation in Ta is contained in this reducible representation. Td A₁ A₂ E Τ1 T₂ r E 1 1 2 3 3 17 8C3 1 1 -1 1 0 0 2 3C₂ 1 1 2 -1 6S4 1 -1 1 101 1.5 7 0 1 713 7. 1.5 -1 -1 60d -3 -1 -1 -5
(iv) Show the symmetry operations for all the symmetry elements present, and determine the transformation matrices by choosing the basis set as (a) all the atoms in A (b) CO groups in C molecules. NH2 CI H CI Со. ''CO OC CI H. 'N' NH2 CO A B
PCl3 belong to C3V point group ? (b) Write down the totally symmetric representation of the point group of PCl3. (c) What is a symmetry-adapted linear combination of atomic orbitals? (d) Construct a linear-combination of 3s(Cl) atomic orbitals, ?1, such that ?1 belongs to the totally symmetric representation of the point group of PCl3. (e) Construct a linear-combination of 3p(Cl) atomic orbitals, ?2, such that ?2 belongs to the totally symmetric representation of the point group of PCl3.
Assign the following molecules to point groups: (i) HF, (ii) IF7 (pentagonal bipyramid), (iii) CIF3 (T-shaped), (iv) Fe2(CO)9 (Image 3), (v) cubane (C8H8), (vi) tetrafluorocubane (C8H4F4) (Image 4).
4. (a) Identify the principal (z) rotational axis for all molecules provided below. (b) Provide a complete list of symmetry operations for each of the following molecules. (c) Which molecules posses identical sets of symmetry operations? Me Me Me Me H3N NH3 NO Oc-FeCO ON-F CO
Å L. Y → X 5 3 Consider the trimethylenecyclopropane molecule (point group D3h). Each carbon atom has a pz orbital to contribute to the pi- MOs of the molecule. Take these 6 pz orbitais as a basis set and answer the following questions: A) How do they divide into subsets of symmetry - equivalent orbitals? B) What representations are spanned by each subset? C) What are the 6 normalized
(a) Identify the symmetry elements in ethene and in allene, and assign each molecule to a point group. (b) Consider the biphenyl molecule, Ph–Ph, in which different conformations are possible according to the value of the dihedral angle between the planes of the two benzene rings: if this angle is 0°, the molecule is planar, if it is 90°, the two rings are perpendicular to one another. For each of the following dihedral angles, identify the symmetry elements present and hence assign the point group: (i) 0°, (ii) 90°, (iii) 45°, (iv) 60°.
(i) the point group to which pyridine (C5H§N) belongs; (ii) the number of internal degrees of freedom for pyridine; (ii) the irreducible representation for pyridine; (iv) the number of IR active C-H stretching modes for pyridine; (v) the number of Raman active C-H stretching modes for pyridine.