1. 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

2. 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

5. 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

6. Monoclinic Model ADP's

7. 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

23. Test P-1 Model for Twinning

24. Overlapped k = 0 Layer

26. Rav (Monoclinic – 2/m) = 21% on F(calc) Model

27. Refined Model in P-1 All H-atoms Found and rerined

28. 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 …..

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