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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