Reflection Data Analysis Tools in PLATON

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Reflection Data Analysis Tools in PLATON
Problem from Bruker Discussion
List Triclinic or Monoclinic?
Ni-complex In P-1,Z'2 a 11.869 b 5.562 c
13.67 Alpha 90.08 Beta 116.38 Gamma
90.06 R1 10 WR2 31
Ton Spek, Utrecht University, The
Netherlands Bruker User Meeting Bad Herrenalb,
Sept. 23, 2012
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Triclinic, Monoclinic ?

• The New SHELXT program offers a starting model in
  P-1 and Pn and P21/n
• PLATON/ADDSYM happily offers a structure in P21/n
  that resembles the solution in P-1

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Alternative Monoclinic Model
In P21/n, Z'1 A 11.869 B 5.562 C
13.67 Alpha 90 Beta 116.38 Gamma 90 R1
17 WR2 53 Poor ADP's
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Monoclinic Model ADP's
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Looking at the Data

• - Investigate thePrimary Data
• - Images, Integration
• - HKL File
• - Redundancy, Laue Symmetry (Rav)
• - Space Group Extinctions
• - Investigate the Refinement Data
• - Analysis of Variance
• - Twinning
• With Tools Available in PLATON

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Test P-1 Model for Twinning
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Overlapped k 0 Layer
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Rav (Monoclinic 2/m) 21 on F(calc) Model
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Refined Model in P-1
All H-atoms Found and rerined
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In Conclusion

• Three additional parameters had to be introduced
  to obtain a nice looking refinement result in
  P-1
• - A twinning parameter
• - Two population parameters Ni1 0.88, Ni2 0.43
• The residual problem explain the non 1.0
  population parameters for Ni.
• - Go back to the chemist ..

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Thanks !

• Example taken from the very
• active and interesting
• Bruker User Discussion List
• Maintained by Ilia Guzai
• Problem and data communicated by
• Babu Varghese

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