html5-img
1 / 19

An Introduction to the Chemistry of Chromium

An Introduction to the Chemistry of Chromium. Ethan Englund Augustana College 05.10.02. Chromium Chemistry. Chromium - Comes form the Greek word “chroma” meaning colored. First Identified in the PbCrO 4 Multiple Oxidation States . Cr(Acac) 3. Full Name is Chromium Acetylacetonate

gayora
Download Presentation

An Introduction to the Chemistry of Chromium

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. An Introduction to the Chemistry of Chromium Ethan Englund Augustana College 05.10.02

  2. Chromium Chemistry • Chromium - Comes form the Greek word “chroma” meaning colored. • First Identified in the PbCrO4 • Multiple Oxidation States

  3. Cr(Acac)3 • Full Name is Chromium Acetylacetonate • Octahedral Complex of Cr III • Optically Active

  4. Chromium Acac Synthesis • Acetylacetone is added to a solution containing Cr (III) ions and urea. • The solution is heated thoroughly for around 1 ~ 2 hours. • Yields a deep red solution with dark red precipitate.

  5. The Ultra Violet Spectrum of Cr(Acac)3

  6. Chromium d Orbital Split • Cr (III) - Typical d3 octahedral metal ion. • Ligand Field Strength Unimportant

  7. Visible Spectrum • Obvious Color • D  D Transitions • From this, the LFSE (o) and B can be determined.

  8. Interpreting Spectrum Data: Tunabe - Sugano Diagram • From this, one can determine the Racah parameter. • Also can give the Octahedral Splitting Energy

  9. Symmetry and Optical Activity • D3 Symmetry • Optical activity possible because of the enantiomers. • Right Hand Screw Vs. Left Hand Screw Formation

  10. Cr(Acac)3 Enatiomers

  11. The Joys of Computational Chem • Above: The Elctrostatic Potential Graphed on the Electron Density via ZINDO on CAChe

  12. Singly and Doubly Occupied Orbitals Prediction based on Jaguar: B88 LYP Some Oddities in the Predictions

  13. T2g Vs. eg Orbitals • Seem to show dx2-y2 orbitals • Along with dz2 indicate eg

  14. Chromium Acetate • Bidentate Acetate Ligands • Metal-Metal Bond • Computational methods and approaches

  15. The Formation of a Delta Bond in a Cr(II) Complex • Commonly referred to as a quadruple bond. • Has 8 available valence electrons • Bond Order of 4

  16. Orbital View of the Quadruple Bond • The d orbitals of the delta bond • dx2-y2 orbitals occupied M-L bonds

  17. Conclusion • Transition Metal Computational Work Continues to Gain Interest • The Chromium Chemistry described shows a lot of generalities in transition metal chemistry

  18. Bibliography • Atkins, Shriver. Inorganic Chemistry: Third Edition. Freeman and Company N.Y. 1999 • Gray, Swanson, Crawford. Project ACAC: An Experimental Investigation In Synthesis and Structure. Bogden and Quigley Inc. Belmont, Ca. 1972

  19. Appreciation goes out to… • Dr. Viste for his invaluable Quantum/Computational advise • Dr. Lindbeck for her guidance in advanced inorganic chemistry • Augustana College

More Related