The ammonium chromium(III) alum NH~4~Cr(SO~4~)~2~.12H~2~O
Rempfer, Nora; Lerner, Hans-Wolfram; Bolte, Michael; Acta Crystallographica, Section E 60 (2004) i80–i81; doi:10.1107/S1600536804011900

data_2203958
_publ_section_title
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The ammonium chromium(III) alum NH~4~Cr(SO~4~)~2~.12H~2~O
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_journal_issue                   7
_journal_name_full               'Acta Crystallographica, Section E'
_journal_page_first              i80
_journal_page_last               i81
_journal_paper_doi               10.1107/S1600536804011900
_journal_volume                  60
_journal_year                    2004
_chemical_formula_iupac          'N H4 Cr (S O 4)2, 12H2 O'
_chemical_formula_moiety         'N H4 1+, Cr (H 2 O)6 3+, ( S O4 2-)2, 6(H2 O)'
_chemical_formula_structural     '(N H4) Cr (H 2 O)6 (S O 4)2 (H2 O)6'
_chemical_formula_sum            'Cr H28 N O20 S2'
_chemical_formula_weight         478.35
_space_group_IT_number           205
_space_group_name_Hall           '-P 2ac 2ab 3'
_space_group_name_H-M_alt        'P a -3'
_symmetry_cell_setting           cubic
_symmetry_space_group_name_Hall  '-P 2ac 2ab 3'
_symmetry_space_group_name_H-M   'P a -3'
_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                   12.2491(12)
_cell_length_b                   12.2491(12)
_cell_length_c                   12.2491(12)
_cell_measurement_reflns_used    4846
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      27.6
_cell_measurement_theta_min      3.7
_cell_volume                     1837.9(3)
_computing_cell_refinement       X-AREA
_computing_data_collection       'X-AREA (Stoe & Cie, 2001)'
_computing_data_reduction        X-AREA
_computing_molecular_graphics    'XP in SHELXTL-Plus (Sheldrick, 1991)'
_computing_publication_material  'SHELXL97 and PLATON (Spek, 1990)'
_computing_structure_refinement  'SHELXL97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 0.986
_diffrn_measured_fraction_theta_max 0.986
_diffrn_measurement_device_type  'Stoe IPDS-II two-circle'
_diffrn_measurement_method       \w
_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  0.0257
_diffrn_reflns_av_sigmaI/netI    0.0176
_diffrn_reflns_limit_h_max       15
_diffrn_reflns_limit_h_min       -12
_diffrn_reflns_limit_k_max       3
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       15
_diffrn_reflns_limit_l_min       -15
_diffrn_reflns_number            5024
_diffrn_reflns_theta_full        27.72
_diffrn_reflns_theta_max         27.72
_diffrn_reflns_theta_min         3.72
_diffrn_standards_decay_%        0
_diffrn_standards_interval_time  0
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.943
_exptl_absorpt_correction_T_max  0.8487
_exptl_absorpt_correction_T_min  0.8054
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   '(MULABS; Spek, 1990; Blessing, 1995)'
_exptl_crystal_colour            violet
_exptl_crystal_density_diffrn    1.729
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             1004
_exptl_crystal_size_max          0.24
_exptl_crystal_size_mid          0.22
_exptl_crystal_size_min          0.18
_refine_diff_density_max         0.287
_refine_diff_density_min         -0.358
_refine_ls_extinction_coef       0.090(3)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL97
_refine_ls_goodness_of_fit_ref   1.037
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     58
_refine_ls_number_reflns         714
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.037
_refine_ls_R_factor_all          0.0245
_refine_ls_R_factor_gt           0.0190
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w = 1/[\s^2^(Fo^2^)+(0.0348P)^2^] where P = (Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0496
_refine_ls_wR_factor_ref         0.0506
_reflns_number_gt                613
_reflns_number_total             714
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            wm6019.cif
_cod_database_code               2203958