The gas-phase structure of octaphenyloctasilsesquioxane Si8O12Ph8 and the crystal structures of Si8O12(p-tolyl)8 and Si8O12(p-ClCH2C6H4)8.
Zakharov, Alexander V.; Masters, Sarah L.; Wann, Derek A.; Shlykov, Sergei A.; Girichev, Georgiy V.; Arrowsmith, Sophie; Cordes, David B.; Lickiss, Paul D.; White, Andrew J. P.; Dalton transactions (Cambridge, England : 2003) 39 (2010) 6960–6966; doi:10.1039/c000664e

data_7025428
_publ_section_title
;
 The gas-phase structure of octaphenyloctasilsesquioxane Si8O12Ph8 and the
 crystal structures of Si8O12(p-tolyl)8 and Si8O12(p-ClCH2C6H4)8.
;
_journal_issue                   30
_journal_name_full
'Dalton transactions (Cambridge, England : 2003)'
_journal_page_first              6960
_journal_page_last               6966
_journal_paper_doi               10.1039/c000664e
_journal_volume                  39
_journal_year                    2010
_chemical_formula_moiety         'C56 H56 O12 Si8, 6(C3 H6 O)'
_chemical_formula_sum            'C74 H92 O18 Si8'
_chemical_formula_weight         1494.20
_chemical_name_systematic
;
?
;
_space_group_IT_number           87
_symmetry_cell_setting           tetragonal
_symmetry_space_group_name_Hall  '-I 4'
_symmetry_space_group_name_H-M   'I 4/m'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   19.4815(3)
_cell_length_b                   19.4815(3)
_cell_length_c                   20.9445(4)
_cell_measurement_reflns_used    4372
_cell_measurement_temperature    173(2)
_cell_measurement_theta_max      70.8155
_cell_measurement_theta_min      3.0898
_cell_volume                     7949.0(2)
_computing_cell_refinement       'CrysAlis RED, Oxford Diffraction Ltd'
_computing_data_collection       'CrysAlis CCD, Oxford Diffraction Ltd'
_computing_data_reduction        'CrysAlis RED, Oxford Diffraction Ltd'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      173(2)
_diffrn_detector_area_resol_mean 8.2556
_diffrn_measured_fraction_theta_full 0.985
_diffrn_measured_fraction_theta_max 0.969
_diffrn_measurement_device_type  'OD Xcalibur PX Ultra'
_diffrn_measurement_method       'phi and omega scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'Enhance Ultra (Cu) X-ray Source'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54184
_diffrn_reflns_av_R_equivalents  0.0449
_diffrn_reflns_av_sigmaI/netI    0.0442
_diffrn_reflns_limit_h_max       16
_diffrn_reflns_limit_h_min       -19
_diffrn_reflns_limit_k_max       23
_diffrn_reflns_limit_k_min       -22
_diffrn_reflns_limit_l_max       21
_diffrn_reflns_limit_l_min       -24
_diffrn_reflns_number            11196
_diffrn_reflns_theta_full        68.50
_diffrn_reflns_theta_max         70.96
_diffrn_reflns_theta_min         3.10
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    1.809
_exptl_absorpt_correction_T_max  0.834
_exptl_absorpt_correction_T_min  0.794
_exptl_absorpt_correction_type   analytical
_exptl_absorpt_process_details
;
CrysAlisPro, Oxford Diffraction Ltd.,
Version 1.171.33.48 (release 15-09-2009 CrysAlis171 .NET)
(compiled Sep 15 2009,11:49:04)
Analytical numeric absorption correction using a multifaceted crystal
model based on expressions derived by R.C. Clark & J.S. Reid.
(Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897)
;
_exptl_crystal_colour            Colourless
_exptl_crystal_density_diffrn    1.249
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       needles
_exptl_crystal_F_000             3168
_exptl_crystal_size_max          0.16
_exptl_crystal_size_mid          0.14
_exptl_crystal_size_min          0.12
_platon_squeeze_details
;
SQUEEZE suggests 809 e/cell = 50.6 e/asu.
The solvents used were dcm = CH2Cl2 = 42e and acetone = C3H6O = 32e
From the non-SQUEEZE version, the shape and flat electron density profile
slightly favours acetone over dcm, but both are possible so the choice
is somewhat arbitrary. Acetone was chosen.
1.5acetone = 48e, so solvent modelled as 1.5acetone/asu = 6acetone/cage.

From SQUEEZE, asu C4.5 H9 O1.5 low, so UNIT C72 H144 O24 low,
i.e. C224 H224 O48 Si32
;
_refine_diff_density_max         0.632
_refine_diff_density_min         -0.442
_refine_diff_density_rms         0.065
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.015
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     195
_refine_ls_number_reflns         3830
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.015
_refine_ls_R_factor_all          0.0844
_refine_ls_R_factor_gt           0.0626
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1169P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1699
_refine_ls_wR_factor_ref         0.1813
_reflns_number_gt                2579
_reflns_number_total             3830
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            c000664e.txt
_cod_data_source_block           2
_cod_depositor_comments
;
The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Tetragonal' changed to 'tetragonal'
according to /home/saulius/struct/CIF-dictionaries/cif_core.dic
dictionary named 'cif_core.dic' version 2.4.2 from 2011-04-26.

Automatic conversion script
Id: cif_fix_values 1891 2012-01-12 08:04:46Z andrius 
;
_cod_original_sg_symbol_H-M      I4/m
_cod_database_code               7025428