Structure and Bonding Studies of Organic and Organometallic SNSN Rings: A Progress Report INOR 507 T

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Structure and Bonding Studies of Organic and
Organometallic SNSN RingsA Progress
ReportINOR 507 - Talk

• Allen D. Hunter, S. Aucot, M. Wheatley, F.
  Blockhuys, A. Zibarev, S. J. Coles, J. D.
  Woollins, C. Van Alsenoy, M. B. Hursthouse, A. M.
  Slawin, and N. K. Hansen.
• adhunter_at_cc.ysu.edu

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NSNS Heterocyclic Materials, Why?

• NxSy Chemistry
• Rich Structural Diversity
• Rings
• Cages
• Chains
• Bonding

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NSNS Heterocyclic Materials, Why?

• NxSy Chemistry
• Rich Organometallic and Organic Chemistry

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NSNS Heterocyclic Materials, Why?

• NxSy Chemistry
• Interesting Bonding
• Structural Analogies to Current Aromatic
  Materials
• Potential for Materials Applications

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Hunters Interest in NSNS Chemistry

• 2000-2001 Sabbatical Goals
• Crystallographic Education Project
• Experience in Main Group Chemistry
• Application of Diffraction Methods to
  Understanding Chemical Bonding
• St. Andrews University
• Woollins Slawin Groups

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Hunters Interest in NSNS Chemistry

• Overall Goal The application of structural
  methods to better understand the chemistry,
  bonding, and materials properties of NSNS
  heterocyclic materials
• The BEONS Collaboration Bonding and
  Electronic/Optical Studies of NS and Related
  Heterocyclic Ring Compounds Potentials for
  Materials Applications

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The BEONS Collaboration
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Hunters Interest in NSNS Chemistry

• Initial Focus
• (4), 5, (6) Membered NSNS Heterocyclic Rings

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Previous Work by Team

• Antwerp, Novosibirsk, St. Andrews, Edinburgh
  (Rankin)

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LnM(NSNS) Questions

• CCDB

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LnM(NSNS) Questions

• CCDB

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(?5-C5R5)M(NSNS)

• (?5-C5H5)Co(NSNS), Preliminary X-Ray
  Crystallographic Results

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(?5-C5H5)Co(NSNS)

• Deformation Map of Cyclopentadienyl Ligand

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(?5-C5H5)Co(NSNS)

• Deformation Map of Heterocyclic Ring

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(?5-C5H5)Co(NSNS)

• Preliminary DFT Theoretical Results

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(?5-C5H5)Co(NSNS) Theoretical Approach

• various methods and (combinations of) basis sets
  have been used to gauge the effect of both on the
  geometry of CpCoNSNS
• B3LYP/6-311G
• B3LYP/6-311G() with no polarization function
  on Co
• B3LYP/aug-cc-pVDZ, the correlation-corrected
  double-zeta basis set with polarization
  functions, augmented with diffuse functions,
  6-311G on Co
• B3LYP/6-311G(3) with 3-21G on Co

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(?5-C5H5)Co(NSNS) Geometry

• B3LYP/6-311G() Preferred

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(?5-C5H5)Co(NSNS) Geometry

• Molecular Electrostatic Potentials Calculated
• negative areas depict the path of approach of an
  electrophilic species

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(?5-C5H5)Co(NSNS) Geometry

• the two N atoms generate potential wells of
  almost equal depth
• the S-minima are shallower and disappear
• from a kinetic point of view a H will approach
  both sites equally easily
• from a thermodynamic point of view, protonation
  of the 4-position is favored (10 kcal.mol-1)

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(?5-C5H5)Co(NSNS) Geometry

• Calculated Difference Electron Densities
• electron density in the C5H5 plane

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(?5-C5H5)Co(NSNS) Geometry

• Calculated Difference Electron Densities
• in the CoNSNS plane

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(?5-C5H5)Co(NSNS) Geometry

• Calculated Difference Electron Densities
• free electron pairs on N atoms are well-defined
• free electron pairs on S atoms are less
  well-defined
• SN bond maxima in electron density are
  unexpectedly low, in comparison with the free
  electron pairs on N
• striking d-type density on Co

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Where Now?

• Complete Calculations
• Integrate Results

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Acknowledgements

• Collaborators
• St. Andrews University J. Derek Woollins,
  Alexandra M. Slawin, Steven Aucot, Mathew
  Wheatley
• University of Antwerp Frank Blockhuys, Kris Van
  Alsenoy
• UHP in Nancy Slimane Dahaoui, Niels Hansen,
  Claude Lecomte
• University of Southampton Simon J. Coles
  Michael B. Hursthouse
• RAS, Novosibirsk Andrey Zibarev

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Acknowledgements

• J. Derek Woollins, St. Andrews University
• National Science Foundation
• INT 0086313
• Youngstown State University
• Sabbatical