α-NH~4~Fe(HAsO~4~)~2~
Ouerfelli, Najoua; Souilem, Amira; Zid, Mohamed Faouzi; Driss, Ahmed; Acta Crystallographica Section E 70 (2014) i21–i22; doi:10.1107/S1600536814008691

data_2239526
_publ_section_title
;
 \a-NH~4~Fe(HAsO~4~)~2~
;
_journal_coeditor_code           BR2238
_journal_issue                   6
_journal_name_full               'Acta Crystallographica Section E'
_journal_page_first              i21
_journal_page_last               i22
_journal_paper_doi               10.1107/S1600536814008691
_journal_volume                  70
_journal_year                    2014
_chemical_formula_iupac          '(N H4) Fe (H As O4)2'
_chemical_formula_moiety         'H4 N +, H2 As2 Fe O8 +'
_chemical_formula_structural     '(N H4) Fe (H As O4)2'
_chemical_formula_sum            'As2 Fe H6 N O8'
_chemical_formula_weight         353.75
_chemical_name_common
;
Ammonium iron(III) bis(hydrogen arsenate(V)
;
_chemical_name_systematic
;
Poly[ammonium bis(\m-hydrogen arsenato)ferrate(III)]
;
_space_group_IT_number           2
_symmetry_cell_setting           triclinic
_symmetry_space_group_name_Hall  '-P 1'
_symmetry_space_group_name_H-M   'P -1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                64.545(5)
_cell_angle_beta                 70.710(7)
_cell_angle_gamma                69.638(6)
_cell_formula_units_Z            3
_cell_length_a                   7.3473(7)
_cell_length_b                   9.1917(8)
_cell_length_c                   9.7504(9)
_cell_measurement_reflns_used    25
_cell_measurement_temperature    298(2)
_cell_measurement_theta_max      15
_cell_measurement_theta_min      11
_cell_volume                     544.55(9)
_computing_cell_refinement
'CAD-4 EXPRESS (Duisenberg, 1992; Mac\'i\<cek & Yordanov, 1992)'
_computing_data_collection
'CAD-4 EXPRESS (Duisenberg, 1992; Mac\'i\<cek & Yordanov, 1992)'
_computing_data_reduction        'XCAD4 (Harms & Wocadlo, 1995)'
_computing_molecular_graphics    'DIAMOND (Brandenburg & Putz, 2001)'
_computing_publication_material
'WinGX (Farrugia, 2012) and publCIF (Westrip, 2010)'
_computing_structure_refinement  'SHELXL97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      298(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'Enraf--Nonius CAD-4'
_diffrn_measurement_method       \w/2\q
_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  0.0212
_diffrn_reflns_av_sigmaI/netI    0.0279
_diffrn_reflns_limit_h_max       1
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       10
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       11
_diffrn_reflns_limit_l_min       -12
_diffrn_reflns_number            2737
_diffrn_reflns_theta_full        26.97
_diffrn_reflns_theta_max         26.97
_diffrn_reflns_theta_min         2.37
_diffrn_standards_decay_%        1.1
_diffrn_standards_interval_time  120
_diffrn_standards_number         2
_exptl_absorpt_coefficient_mu    11.136
_exptl_absorpt_correction_T_max  0.388
_exptl_absorpt_correction_T_min  0.187
_exptl_absorpt_correction_type   psi-scan
_exptl_absorpt_process_details   '(North <i>et al.</i>,  1968)'
_exptl_crystal_colour            green
_exptl_crystal_density_diffrn    3.236
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             507
_exptl_crystal_size_max          0.213
_exptl_crystal_size_mid          0.132
_exptl_crystal_size_min          0.085
_refine_diff_density_max         1.305
_refine_diff_density_min         -1.208
_refine_ls_extinction_coef       0.0048(7)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXL97 (Sheldrick, 2008)'
_refine_ls_goodness_of_fit_ref   1.050
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     197
_refine_ls_number_reflns         2373
_refine_ls_number_restraints     8
_refine_ls_restrained_S_all      1.049
_refine_ls_R_factor_all          0.0325
_refine_ls_R_factor_gt           0.0268
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0471P)^2^+0.7636P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0723
_refine_ls_wR_factor_ref         0.0754
_reflns_number_gt                2121
_reflns_number_total             2373
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            br2238sup1.cf
_cod_data_source_block           I
_cod_depositor_comments          'Adding full bibliography for 2239526.cif.'
_cod_database_code               2239526
_cod_database_fobs_code          2239526