Two Hydrous Divalent-Metal Diarsenates
Wu, C.-H.; Chen, T.-C.; Wang, S.-L.; Acta Crystallographica Section C 52 (1996) 1326–1329; doi:10.1107/S0108270195016350

data_2004957
_publ_section_title
;
 Two Hydrous Divalent-Metal Diarsenates
;
_journal_issue                   6
_journal_name_full               'Acta Crystallographica Section C'
_journal_page_first              1326
_journal_page_last               1329
_journal_paper_doi               10.1107/S0108270195016350
_journal_volume                  52
_journal_year                    1996
_chemical_formula_iupac          'Mg2 As2 O7 , 2H2 O'
_chemical_formula_moiety         'Mg2 As2 O7 (H2 O)2'
_chemical_formula_sum            'As2 H4 Mg2 O9'
_chemical_formula_weight         346.5
_space_group_crystal_system      monoclinic
_space_group_IT_number           14
_space_group_name_Hall           '-P 2yn'
_space_group_name_H-M_alt        'P 1 21/n 1'
_symmetry_space_group_name_H-M   'P 1 21/n 1'
_atom_type_scat_source           'SHELXTL-Plus (Sheldrick, 1991)'
_cell_angle_alpha                90
_cell_angle_beta                 93.95(2)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   6.499(1)
_cell_length_b                   14.191(4)
_cell_length_c                   7.607(2)
_cell_measurement_reflns_used    16
_cell_measurement_temperature    296
_cell_measurement_theta_max      14.4
_cell_measurement_theta_min      6.6
_cell_volume                     699.9(3)
_computing_cell_refinement       SHELXTL-Plus
_computing_data_collection       'SHELXTL-Plus (Sheldrick, 1991)'
_computing_data_reduction        SHELXTL-Plus
_computing_molecular_graphics    SHELXTL-Plus
_computing_publication_material  SHELXTL-Plus
_computing_structure_refinement  SHELXTL-Plus
_computing_structure_solution    SHELXTL-Plus
_diffrn_measurement_device       'Siemens R3m/V diffractometer'
_diffrn_measurement_method       2\q--\q
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073\%A
_diffrn_reflns_av_R_equivalents  0.0232
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       -8
_diffrn_reflns_limit_k_max       18
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       9
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            1816
_diffrn_reflns_theta_max         27.5
_diffrn_standards_decay_%        none
_diffrn_standards_interval_count 50
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    9.75
_exptl_absorpt_correction_T_max  0.7541
_exptl_absorpt_correction_T_min  0.4183
_exptl_absorpt_correction_type
'empirical via \y scans (SHELXTL-Plus; Sheldrick, 1991)'
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    3.288
_exptl_crystal_density_meas      ?
_exptl_crystal_description       rod
_exptl_crystal_size_max          0.23
_exptl_crystal_size_mid          0.14
_exptl_crystal_size_min          0.13
_refine_diff_density_max         0.77
_refine_diff_density_min         -0.80
_refine_ls_abs_structure_details none
_refine_ls_extinction_coef       '\c = 0.0021(2)'
_refine_ls_extinction_method     'F* = F[1+0.002\cF~2~/sin(2\q)]^-1/4^'
_refine_ls_goodness_of_fit_obs   0.997
_refine_ls_hydrogen_treatment    noref
_refine_ls_number_parameters     119
_refine_ls_number_reflns         1333
_refine_ls_R_factor_obs          0.0253
_refine_ls_shift/esd_max         0.001
_refine_ls_structure_factor_coef F
_refine_ls_weighting_details     'w = 1/[\S~2~(F) + 0.0009F~2~]'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_obs         0.0278
_reflns_number_observed          1333
_reflns_number_total             1605
_reflns_observed_criterion       I>3\s(I)
_cod_data_source_file            br1130.cif
_cod_data_source_block           I
_cod_depositor_comments
;
The following automatic conversions were performed:
'_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic'
according to '/home/saulius/struct/CIF-dictionaries/cif_core.dic'
dictionary named 'cif_core.dic' version 2.4.1 from 2010-06-29.

Automatic conversion script
Id: cif_fix_enum 1527 2010-12-29 10:47:43Z saulius 

The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic'
according to /home/saulius/struct/CIF-dictionaries/cif_core.dic
dictionary named 'cif_core.dic' version 2.4.1 from 2010-06-29.

Automatic conversion script
Id: cif_fix_values 1715 2011-07-08 13:25:40Z adriana 

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 'w = 1/[\S~2~(F) + 0.0009F~2~]'
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~(F) +
0.0009F~2~]'.

Automatic conversion script
Id: cif_fix_values 3143 2015-03-26 13:38:13Z robertas 
;
_cod_original_cell_volume        699.9(8)
_cod_original_sg_symbol_H-M      'P 21/n'
_cod_database_code               2004957