CCD data and shelxl-93 refinement

Xiang Ouyang ouyang at argus.cem.msu.edu
Mon Dec 16 19:32:19 EST 1996


Dear Dr.Sheldrick

Thank you for your post-reply.
The R(sigma) for the data is 0.0472. The |E*E|-1 is 0.993 and the R(int)
for Crystal system H and Lattice type P are 0.057(P-3),
0.065(P-3m1,P-31m,P-6, P6/m) and 0.70(P6/mmm). I have attached a file
generated by the xprep program to this post.
It may be a twinned crystal, so we are tried to solve it with the
acentric space group P6cc. It could be twinned from three monoclic
cells, too. I have not tried this option yet. Another posibility for the
very high R1 might be caused by the 20 solvent molecule CH2Cl2. 
Thank you again

Xiang Ouyang
Dept. of Chem.
Michgan State University
ouyang at argus.cem.msu.edu
 

gsheldr at shelx.uni-ac.gwdg.de wrote:
> 
> Reply to message from Xiang Ouyang "CCD data and shelxl-93 refinement"
> 
> Dear Dr Ouyang
> 
> I strongly recommend processing Siemens CCD data with the program called
> SADABS before refining with SHELXL-93.  SADABS not only applies an
> empirical absorption correction, it also puts the sigma(I) values onto
> an approximately absolute scale.  It is avaliable free to Siemens CCD users
> only.  If the crystal is triclinic it is important to make several different
> phi or omega scans to get enough redundancy for SADABS to work well, for high
> symmetry crystals the standard scans are adequate, so it should work well on
> your data (however it must be told the correct Laue group, probably 6/mmm).
> 
> You cannot fudge the bad sigmas with the WGHT card in SHELXL-93,  With HKLF
> you can multiply the sigmas by a constant, but this is unlikely to be a good
> approach.
> 
> P6cc may well be the right space group, though there is a possibility of
> merohedral twinning in such cases (what are the mean E^2-1 value and the
> Rint values for the various possible Laue groups ?).
> 
> Sincerely, George Sheldrick
-------------- next part --------------

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+  XPREP - DATA PREPARATION & RECIPROCAL SPACE EXPLORATION Ver. 5.03 / IRIX  +
+  COPYRIGHT(c) 1990-5 Siemens Analytical X-ray Insts.  All Rights Reserved  +
+  check                                   started at 19:13:45 on 16-Dec-96  +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


Original cell in Angstroms and degrees:

   46.861   46.860   22.782    89.97    90.06   119.96

  115133 Reflections read from file check.hkl; mean (I/sigma) =   11.64


Lattice exceptions:  P      A      B      C      I      F     Obv    Rev    All

N (total) =           0  57099  56993  57644  57094  85868  76642  76560 115133
N (int>3sigma) =      0  44689  44843  45750  44734  67641  60693  60744  91124
Mean intensity =    0.0    5.8    5.7    6.6    5.8    6.0    6.5    6.5    6.6
Mean int/sigma =    0.0   11.3   11.3   11.8   11.3   11.5   11.6   11.6   11.7

Lattice type: P chosen          Volume:     43342.21

-------------------------------------------------------------------------------

DETERMINATION OF REDUCED (NIGGLI) CELL

Transformation from original cell (HKLF-matrix): 
    0.0000  0.0000  1.0000    0.0000  1.0000  0.0000   -1.0000  0.0000  0.0000

Unitcell:      22.782   46.860   46.861   60.04   89.94   89.97

Niggli form:     a.a =    519.02      b.b =   2195.86      c.c =   2195.95
                 b.c =   1096.63      a.c =      1.12      a.b =      0.56

-------------------------------------------------------------------------------

SEARCH FOR HIGHER METRIC SYMMETRY

------------------------------------------------------------------------------
Option A: FOM = 0.073 deg.   HEXAGONAL     P-lattice   R(int) = 0.057 [ 66000]
Cell:   46.861  46.860  22.782   89.97   90.06  119.96    Volume:     43342.20
Matrix: 1.0000  0.0000  0.0000  0.0000  1.0000  0.0000  0.0000  0.0000  1.0000
------------------------------------------------------------------------------
Option B: FOM = 0.060 deg.   ORTHORHOMBIC  C-lattice   R(int) = 0.060 [ 75637]
Cell:   46.889  81.148  22.782   90.05   90.03   90.00    Volume:     86684.41
Matrix:-1.0000 -1.0000  0.0000 -1.0000  1.0000  0.0000  0.0000  0.0000 -1.0000
------------------------------------------------------------------------------
Option C: FOM = 0.065 deg.   ORTHORHOMBIC  C-lattice   R(int) = 0.061 [ 75926]
Cell:   46.860  81.198  22.782   89.95   89.97   90.04    Volume:     86684.42
Matrix: 0.0000  1.0000  0.0000 -2.0000 -1.0000  0.0000  0.0000  0.0000  1.0000
------------------------------------------------------------------------------
Option D: FOM = 0.073 deg.   ORTHORHOMBIC  C-lattice   R(int) = 0.059 [ 76014]
Cell:   46.861  81.197  22.782   90.00   89.94   89.96    Volume:     86684.42
Matrix:-1.0000  0.0000  0.0000 -1.0000 -2.0000  0.0000  0.0000  0.0000  1.0000
------------------------------------------------------------------------------
Option E: FOM = 0.030 deg.   MONOCLINIC    C-lattice   R(int) = 0.049 [ 50058]
Cell:   81.148  46.889  22.782   90.03   90.05   90.00    Volume:     86684.41
Matrix: 1.0000 -1.0000  0.0000  1.0000  1.0000  0.0000  0.0000  0.0000  1.0000
------------------------------------------------------------------------------
Option F: FOM = 0.041 deg.   MONOCLINIC    C-lattice   R(int) = 0.049 [ 50863]
Cell:   46.861  81.197  22.782   90.00   90.06   89.96    Volume:     86684.42
Matrix: 1.0000  0.0000  0.0000  1.0000  2.0000  0.0000  0.0000  0.0000  1.0000
------------------------------------------------------------------------------
Option G: FOM = 0.049 deg.   MONOCLINIC    C-lattice   R(int) = 0.050 [ 49480]
Cell:   81.198  46.860  22.782   89.97   90.05   89.96    Volume:     86684.42
Matrix: 2.0000  1.0000  0.0000  0.0000  1.0000  0.0000  0.0000  0.0000  1.0000
------------------------------------------------------------------------------
Option H: FOM = 0.052 deg.   MONOCLINIC    C-lattice   R(int) = 0.049 [ 48039]
Cell:   46.889  81.148  22.782   89.95   90.03   90.00    Volume:     86684.41
Matrix: 1.0000  1.0000  0.0000 -1.0000  1.0000  0.0000  0.0000  0.0000  1.0000
------------------------------------------------------------------------------
Option I: FOM = 0.060 deg.   MONOCLINIC    P-lattice   R(int) = 0.051 [ 48183]
Cell:   46.860  22.782  46.861   90.06  119.96   89.97    Volume:     43342.21
Matrix: 0.0000  1.0000  0.0000  0.0000  0.0000  1.0000  1.0000  0.0000  0.0000

Option A selected

-------------------------------------------------------------------------------

SPACE GROUP DETERMINATION


Lattice exceptions:  P      A      B      C      I      F     Obv    Rev    All

N (total) =           0  57099  56993  57644  57094  85868  76642  76560 115133
N (int>3sigma) =      0  44689  44843  45750  44734  67641  60693  60744  91124
Mean intensity =    0.0    5.8    5.7    6.6    5.8    6.0    6.5    6.5    6.6
Mean int/sigma =    0.0   11.3   11.3   11.8   11.3   11.5   11.6   11.6   11.7


Crystal system H and Lattice type P selected

Mean |E*E-1| = 0.993 [expected .968 centrosym and .736 non-centrosym]

Chiral flag NOT set



Systematic absence exceptions:

        61/65 62=31  63    -c-   --c 

N        30    24    15  1559  1139
N I>3s   28    23    13   793   583
<I>   404.1 501.6  11.8   1.0   0.9
<I/s>  29.8  31.0  24.0   4.8   4.5


Option  Space Group  No.  Type  Axes  CSD  R(int) N(eq)  Syst. Abs.   CFOM

[A] P-3            #147  centro   1    54  0.057 66000   0.0 /  4.5   6.13
[B] P3             #143  chiral   1    15  0.057 66000   0.0 /  4.5  17.09
[C] P-3m1          #164  centro   1    19  0.065 87911   0.0 /  4.5   7.37
[D] P321           #150  chiral   1     6  0.065 87911   0.0 /  4.5  23.18
[E] P3m1           #156  non-cen  1     1  0.065 87911   0.0 /  4.5  58.90
[F] P31m           #157  non-cen  1     4  0.065 88256   0.0 /  4.5  28.84
[G] P-31m          #162  centro   1     0  0.065 88256   0.0 /  4.5 102.31
[H] P312           #149  chiral   1     0  0.065 88256   0.0 /  4.5 108.84
[I] P-6            #174  non-cen  1     2  0.065 87994   0.0 /  4.5  42.28
[J] P6             #168  chiral   1     2  0.065 87994   0.0 /  4.5  42.28
[K] P6/m           #175  centro   1     1  0.065 87994   0.0 /  4.5  52.42
[L] P6/mmm         #191  centro   1     3  0.070100385   0.0 /  4.5  27.58
[M] P-62m          #189  non-cen  1     3  0.070100385   0.0 /  4.5  34.11
[N] P622           #177  chiral   1     2  0.070100385   0.0 /  4.5  42.45
[O] P-6m2          #187  non-cen  1     0  0.070100385   0.0 /  4.5 109.11
[P] P6mm           #183  non-cen  1     0  0.070100385   0.0 /  4.5 109.11

Option [A] chosen

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