Two tetramethylxanthenediones
Jeyakanthan, J.; Shanmuga Sundara Raj, S.; Velmurugan, D.; Hoong-Kun Fun; Murugan, P.; Acta Crystallographica Section C 55 (1999) 1515–1517; doi:10.1107/S0108270199006393

data_2008894
_publ_section_title
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 Two tetramethylxanthenediones
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_journal_issue                   9
_journal_name_full               'Acta Crystallographica Section C'
_journal_page_first              1515
_journal_page_last               1517
_journal_paper_doi               10.1107/S0108270199006393
_journal_volume                  55
_journal_year                    1999
_chemical_formula_sum            'C17 H22 O3'
_chemical_formula_weight         274.35
_chemical_name_systematic
;
1,2,3,4,5,6,7,8-octahydro-3,3,6,6-tetramethylxanthen-1,8-dione
;
_space_group_IT_number           2
_symmetry_cell_setting           triclinic
_symmetry_space_group_name_Hall  '-P 1'
_symmetry_space_group_name_H-M   'P -1'
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_cell_angle_beta                 96.074(11)
_cell_angle_gamma                101.302(10)
_cell_formula_units_Z            2
_cell_length_a                   7.1458(8)
_cell_length_b                   9.7690(12)
_cell_length_c                   11.886(2)
_cell_measurement_reflns_used    27
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      24.84
_cell_measurement_theta_min      9.07
_cell_volume                     746.65(19)
_computing_cell_refinement       XSCANS
_computing_data_collection       'XSCANS (Siemens, 1994)'
_computing_data_reduction        XSCANS
_computing_molecular_graphics    'ORTEPIII (Johnson & Burnett, 1997)'
_computing_publication_material  'SHELXTL and PARST (Nardelli, 1995)'
_computing_structure_refinement  SHELXTL
_computing_structure_solution    'SHELXTL (Siemens, 1996)'
_diffrn_ambient_temperature      293(2)
_diffrn_measurement_device       'Siemens P4'
_diffrn_measurement_method       '\q/2\q scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.030
_diffrn_reflns_av_sigmaI/netI    0.044
_diffrn_reflns_limit_h_max       9
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_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       15
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_diffrn_standards_decay_%        <2
_diffrn_standards_interval_count 97
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    0.082
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.220
_exptl_crystal_density_meas      ?
_exptl_crystal_description       'rectangular block'
_exptl_crystal_F_000             296
_exptl_crystal_size_max          0.64
_exptl_crystal_size_mid          0.28
_exptl_crystal_size_min          0.24
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_refine_diff_density_min         -0.20
_refine_ls_extinction_coef       0.011(5)
_refine_ls_extinction_method     'SHELXTL (Siemens, 1996)'
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_refine_ls_restrained_S_obs      1.131
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_refine_ls_R_factor_obs          0.044
_refine_ls_shift/esd_max         <0.001
_refine_ls_shift/esd_mean        0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w = 1/[\s^2^(Fo^2^)+(0.0772P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_all         0.139
_refine_ls_wR_factor_obs         0.123
_reflns_number_observed          2301
_reflns_number_total             3333
_reflns_observed_criterion       I>2\s(I)
_cod_data_source_file            fr1174.cif
_cod_data_source_block           I
_cod_depositor_comments
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The following automatic conversions were performed:

'_exptl_crystal_density_meas' value 'not measured' was changed to '?'
- the value is perceived as not measured.

Automatic conversion script
Id: cif_fix_values 3008 2015-01-20 13:52:24Z robertas 

The following automatic conversions were performed:

'_refine_ls_weighting_scheme' value 'calc w =
1/[\s^2^(Fo^2^)+(0.0772P)^2^] where P=(Fo^2^+2Fc^2^)/3' was changed
to 'calc'. New tag '_refine_ls_weighting_details' was created. The
value of the new tag was set to 'w = 1/[\s^2^(Fo^2^)+(0.0772P)^2^]
where P=(Fo^2^+2Fc^2^)/3'.

Automatic conversion script
Id: cif_fix_values 3143 2015-03-26 13:38:13Z robertas 
;
_cod_original_cell_volume        746.6(2)
_cod_database_code               2008894