Student Explorations in the Collection and Interpretation of Thermochemical and Spectroscopic Data

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

2. Molecular Modeling Exercises

3. Molecular Modeling Exercises 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: Create Process Visualize

7. The Software: Create Process Visualize HyperChem Spartan PCModel Chem3D GaussView WebMO MOE Cache Many Others

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

9. The Software: Create Process Visualize 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. Example: Phenolphthalein Color Change 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. Compare theoretical uv/VIS spectra of the two forms H2In In2-

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 DH=+35 kJ potassium acetate  exothermic DH=-15 kJ Why? What factors are involved?

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

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

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

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

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

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

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

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 ...