Final Exam based on

Syllabus: Structure & Bonding 160:344 Spring 2007

 

  1. Basic Principles of Quantum Chemistry

The Four Grand Approximations: (a two-way street)

Q1) State them in mathematical terms and give examples from chemical principles

i) Born-Oppenheimer

ii)Orbital

iii)LCAO-MO

iv)Gaussian

Lab 1. Orbitals as functions; Maple

Q2) Use the results of your lab on HHe+ to demonstrate how i) exponents of AO’s show electronegativity differences and relative sizes of atoms and ii) how the LCAO coefficients show electron density distributions in molecules.

 

Lab 2. GaussView; Gaussian03

Symmetry

Q3a) Determine the symmetry group of the two molecules on the left of the board;

Q3b) determine the symmetry group of the molecule on the rhs of the board and verify your decision by using GaussView.

 

  1. Calculated Properties

 

States and Orbitals: (Beyond the Orbital Approximation)

UV-Vis Spectroscopy

Lab 3. H2, HeH+, LiH2+, H2C=O

Q4) Detail the results of your experiment using the CIS method to determine the absorption and emission spectra of your substituted carbonyls. Indicate the nature of the first three states for the optimized geometry. Locate and optimize the geometries for the n and pi to pi* transitions. Give orbital energy diagrams and electronic energy state diagrams plotted against the C=O distance. Comment on the optimized geometries of the states.

Singlet, Triplet…, d orbitals

Lab 4. Inorganic Complexes: high spin – low spin

Q5) Detail the results of your experiments to determine whether the ground state is a singlet or quintet in your series from [FeF6]3- to [Fe(CN)]6-

Q6) Pick any complex and find the d orbital energy levels and plot the pictures of the d orbitals. Compare your results to pictures for octahedral complexes using Crystal Field Theory found in your first year chemistry text. What might be lifting the degeneracy expected for octahedral complexes?

Vibrational States: IR Spectroscopy

Lab 5. Normal modes; resonance and electronegativity

 

Nuclear Magnetic Resonance

Chemical Shift

Lab 6. Functional groups revisited; resonance and electronegativity

Nucleus Independent Chemical Shift

Lab 7. Aromaticity

 

  1. Energetics

 

Equilibrium and Transition State Geometries

Lab 8. Rotational Barriers

Thermodynamic Properties

Lab 9. Chemical Reactions; mechanisms

Q7) Discuss the results of your series of Diels-Alder cycloadditions of 5-membered heterocyclic dienes and ene.

i)                How did you assure yourself that the geometries of the reactants, products , and TS were the best possible within the theoretical method you used?

ii)               Did a trend in “early and late” TS structures appear?

iii)             How good were the correlations of Ea vs. deltE and Ea vs. rC…C? From these results would you expect Hammond’s Postulate to be applicable to this reaction (why or why not)?

iv)             Comment on the aromaticity of the isolated diene and of the TS.

Solvent

Lab 10. Solvent Reaction Field

Q8) For those who got to this point, did the results or trends in the D-A reaction change appreciably in nonpolar and polar solvents? Name the effects of solvation in water that are missing from the SRF method.

  1. The Solid State and Polymers

Lab 11. Band Structure; conformation; energetic

Q9) What were your calculated energy differences for the a, g, ag, and gg’ conformations of polyethylene?