Reflection Data Analysis Tools in PLATON

Problemfrom Bruker Discussion

List:Triclinic

orMonoclinic?

Ni-complexIn P-1,Z'=2:a = 11.869b = 5.562c = 13.67

Alpha = 90.08Beta = 116.38

Gamma = 90.06R1 = 10%

WR2 = 31%Ton Spek, Utrecht University, The Netherlands

Bruker User Meeting Bad Herrenalb, Sept. 23, 2012

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

Alternative Monoclinic Model

In P21/n, Z'=1:

A = 11.869B = 5.562C = 13.67Alpha = 90

Beta = 116.38Gamma = 90

R1 = 17%WR2 = 53%

Poor ADP's

Monoclinic Model ADP's

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

Test P-1 Model for Twinning

Overlapped k = 0 Layer

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

Refined Model in P-1

All H-atoms Found and

rerined

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 …..

Thanks !

Example taken from the veryactive and interesting

Bruker User Discussion ListMaintained by Ilia Guzai

Problem and data communicated by Babu Varghese