Reactions of Group III and IV Transition Metals with CS2 and OCS

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Reactions of Group III and IV Transition Metals
with CS2 and OCS

• Alexander B. BakerDr. Lester Andrews

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Outline

• Background and Experimental methods
• Group III with CS2
• Group IV with CS2
• Group IV with OCS
• Conclusions and Future Goals

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Motivation for the Study

• Carbon dioxide studies with transition metals are
  relatively abundant.
• Carbon disulfide experiments are not.
• Heterocumulenes deserve further study
• Possible sources of C1 chemistry.
• Potential roles in biochemistry, materials
  science and catalysis.

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Why Matrix Isolation?

• Matrix Isolation Spectroscopy remains
  underutilized for studies of CS2, CO2, and OCS
• Our lab has previously published studies
• No study of OCS has been performed with
  transition metals and matrix isolation.

w/CO2
w/CS2 and CO2
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Matrix Isolation
1064nm
10-7 Torr
7K
FT-IR
MetalTarget
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Molecular Modeling

• Gaussian 98 package
• Methods
• DFT
• BPW91
• B3LYP
• Medium/Large Basis Sets
• 6-311G(2d,p)
• SDD pseudo-potentials on metal atoms

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Experiments
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Primary Insertion ProductLa CS2 and Isotopes
13C32S2
12C34S2
12C32S2
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Secondary Insertion ProductSc CS2 and
Isotopes
M
S
S
C
13C32S2
12C34S2
12C32S2
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Metal Sulfur StretchY CS2 and Isotopes
13C32S2
12C34S2
12C32S2
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Sample Data (Sc CS2)
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An Interesting Result
M
S
C
S
Energy
2.7 kcal/mol
M
C
S
S
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CO InsertionGroup IV OCS
Hf OCS
Zr OCS
Ti OCS
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Conclusions

• Group III and Group IV transition metals react
  with CS2
• Primary and Secondary insertion products are
  formed and are interconvertible
• Group IV metals react with OCS
• Both CS and CO insertion
• More information needed to draw comparisons
  between CS2, CO2 and OCS.

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Future Work with CS2

• Experimental
• Refine Laser power and photolysis
• A deeper look at sulfur chemistry
• FTIR and UV-Vis together
• Theory
• Triplet state calculations for Group IV CS2
• MP2 and Coupled Cluster Calculations
• Natural Bond Order and population calculations
• Overall
• Group III OCS merits further examination

Thank you Dr. Andrews, Jonathan T. Lyon,
Han-Gook Cho, Binyong Liang, Mingfei
Zhou Funding NSF 03-52487, IGERT (NSF) 99-72790
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References

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p Back-Bonding
s Bonding
p Back Bonding
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S4 Isomerization

• 8 kcal/mol energy difference between the two
  states
• Considerable Energy Overlap between the two
  excited states
• Allows dynamic rearrangement between the two
  isomers
• The Matrix then traps the product.

Hassanzadeh, P. Andrews, L. J. Phys. Chem. 1992,
96, 6579
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Relativistic Effects

• As Z increases, the electron must have a higher
  kinetic energy to avoid collisions with the
  nucleus.
• Einstein proposed that the mass of a particle is
  dependant on its speed
• Vibrational frequency red shifts due to higher
  mass.

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