1. Student Explorations in the Collection and Interpretation of Thermochemical and Spectroscopic Data Theory and Experiment: James B. Foresman York College of PA York PA 17405 USA JForesma@YCP.EDU http://goose.ycp.edu/~jforesma

2. Molecular Modeling Exercises

3. Context: Laboratory Setting (so time to solution is a consideration)

4. Molecular Modeling Exercises Focus: Visualizing Chemistry (linking benchtop to molecular level)

5. Molecular Modeling Exercises Outcome: Understanding Computer Models and Programs (both the mechanics of using the tools and realizing the strengths and limitations of the models)

6. The Software: CreateProcessVisualize

7. The Software: CreateProcessVisualize HyperChem Spartan PCModel Chem3D GaussView WebMO MOE Cache Many Others

8. The Software: CreateProcessVisualize HyperChem Spartan PCModel Chem3D GaussView WebMO MOE Cache Many Others HyperChem Spartan PCModel Chem3D Gaussian ADF Jaguar Gamess Many Others

9. The Software: CreateProcessVisualize HyperChem Spartan PCModel Chem3D GaussView WebMO MOE Cache Many Others HyperChem Spartan PCModel Chem3D Gaussian ADF Jaguar Gamess Many Others HyperChem Spartan PCModel Chem3D GaussView Molekel gOpenMol T3D, MOE Many Others

10. Example: Phenolphthalein Color Change Acid-Base titrations are routinely performed in introductory courses. Why does the solution containing the indicator turn pink?

11. Example: Phenolphthalein Color Change

12. www.cambridgesoft.com

13. Example: Phenolphthalein Color Change www.gaussian.com

14. Example: Phenolphthalein Color Change www.cambridgesoft.com

15. Name to Structure in ChemDraw, paste into Chem3D

16. Reoptimize the structure without hydrogens …

17. H 2 In In 2- Compare theoretical uv/VIS spectra of the two forms

18. Compare HOMO and LUMO Orbitals of the two forms HOMO Of Protonated form

19. Compare HOMO and LUMO Orbitals of the two forms LUMO Of Protonated form

20. Compare HOMO and LUMO Orbitals of the two forms HOMO Of Dianion form

21. Compare HOMO and LUMO Orbitals of the two forms LUMO Of Dianion form

22. Example: Heat of Solution Students can use a primitive device to measure the temperature change when a solid is added to water. potassium nitrate  endothermic  H=+35 kJ potassium acetate  exothermic  H=-15 kJ Why? What factors are involved?

23. www.gaussian.com Example: Heat of Solution

27. Example: Comparing Azulene and Naphthalene Students can measure heats of combustion. Also they can compare IR, uv-VIS, and NMR spectra of these two isomers. What electronic details account for the differences that are observed?

28. www.webmo.net Example: Comparing Azulene and Naphthalene

37. azulene naphthalene Heats of Combustion [kJ/mol] -5291 -5156  H iso = -135 kJ/mol Example: Comparing Azulene and Naphthalene

38.  H iso Theoretical and Experimental Estimates Huckel-46 kJ/mol AM1-177 HF/6-31G(d)-181 B3LYP/6-31G(d)-141 CBS-Q-147

39.  H iso Theoretical and Experimental Estimates Huckel-46 kJ/mol AM1-177 HF/6-31G(d)-181 B3LYP/6-31G(d)-141 CBS-Q-147 Gas phase Expt-148

40. Example: Electronic Spectrum of a Vanadium Complex Students prepare and obtain the uv-VIS spectrum of vanadyl acetylacetonate and attempt to classify the transitions as: d-d d-ligand ligand-ligand ligand-metal

41. www.serenasoft.com Example: Electronic Spectrum of a Vanadium Complex

42. www.gaussian.com Example: Electronic Spectrum of a Vanadium Complex

43. www.cscs.ch/molekel/ Example: Electronic Spectrum of a Vanadium Complex

44. student obtained spectra for VO(acac)2

45. more concentrated sample...

47. load gaussian output file into Molekel and examine optimized B3LYP LANL2DZ distances...

48. load gaussian cubes into Molekel, subtract ground from excited state for this d-d transition

49. other transitions can be visualized...

52. NBO analysis on ground state...

53. can be compared to excited states: d-d

54. ligand-d can be compared to excited states:

55. Example: 2-Nitroaniline C-13 NMR Spectrum Students can obtain the carbon and proton NMR spectra of this compound and make assignments based on comparisons to nitrobenzene and aniline. Use theory to explain any differences in the predictions made by substituent additivity.

56. 2-nitroaniline

61. Example: Sulfur Hexafluoride Intermolecular Forces Students collect PVT data for a sample of SF 6 at high pressures (critical temp is 45 o C) Second Virial Coefficients are examined: comparison is made to: literature reference model potentials

62. Several model potentials can be tested and then B(T) is graphed according to this equation:

65. Example: Isoflurane Conformers and VCD Spectra Students work as a team to explore the various rotational and optical isomers of this flexible small molecule. IR and VCD spectra are obtained for each. Comparison is made to literature spectra (no VCD instrument yet) Application of Boltzmann Distribution function Exercise suggested by the paper: Biedermann, Cheeseman, Frisch, Schurig, Gutman, Agranat, J. Org. Chem. 1999, 64, 3878

66. www.chemcomp.com Example: Isoflurane Conformers and VCD Spectra

67. MOE builder interface...

68. MOE conformational search... results are exported to a database containing structures and energies

69. Gaussian IR and VCD computations...

70. Thanks Carl Salter, Moravian College Don Clarke, Fordham University Wayne Anderson, Bloomsburg University Hans Peter Luthi, ETH Zurich Stefan Portmann, CSCS/ETH Zurich