Non-centrosymmetric Na~3~Nb~4~As~3~O~19~
Chérif, Saïda Fatma; Hizaoui, Khaled; Zid, Mohamed Faouzi; Driss, Ahmed; Acta Crystallographica Section E 68 (2012) i25–i26; doi:10.1107/S1600536812010537

data_2234381
_publ_section_title
;
 Non-centrosymmetric Na~3~Nb~4~As~3~O~19~
;
_journal_coeditor_code           RU2026
_journal_issue                   4
_journal_name_full               'Acta Crystallographica Section E'
_journal_page_first              i25
_journal_page_last               i26
_journal_paper_doi               10.1107/S1600536812010537
_journal_volume                  68
_journal_year                    2012
_chemical_formula_iupac          'Na3 Nb4 As3 O19'
_chemical_formula_moiety         'As3 Na3 Nb4 O19'
_chemical_formula_sum            'As3 Na3 Nb4 O19'
_chemical_formula_weight         969.37
_chemical_name_systematic
;
trisodium tetraniobium triarsenic nonadecaoxide
;
_space_group_IT_number           20
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'C 2c 2'
_symmetry_space_group_name_H-M   'C 2 2 21'
_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                   13.014(2)
_cell_length_b                   24.170(3)
_cell_length_c                   5.0880(9)
_cell_measurement_reflns_used    25
_cell_measurement_temperature    298(2)
_cell_measurement_theta_max      15
_cell_measurement_theta_min      10
_cell_volume                     1600.4(4)
_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, 1998)'
_computing_publication_material  'WinGX (Farrugia, 1999)'
_computing_structure_refinement  'SHELXL97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      298(2)
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_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  0.0412
_diffrn_reflns_av_sigmaI/netI    0.0466
_diffrn_reflns_limit_h_max       16
_diffrn_reflns_limit_h_min       -1
_diffrn_reflns_limit_k_max       30
_diffrn_reflns_limit_k_min       -1
_diffrn_reflns_limit_l_max       6
_diffrn_reflns_limit_l_min       -6
_diffrn_reflns_number            2116
_diffrn_reflns_theta_full        26.96
_diffrn_reflns_theta_max         26.96
_diffrn_reflns_theta_min         2.97
_diffrn_standards_decay_%        1
_diffrn_standards_interval_time  120
_diffrn_standards_number         2
_exptl_absorpt_coefficient_mu    9.134
_exptl_absorpt_correction_T_max  0.230
_exptl_absorpt_correction_T_min  0.083
_exptl_absorpt_correction_type   psi-scan
_exptl_absorpt_process_details   '(North <i>et al.</i>, 1968)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    4.023
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             1792
_exptl_crystal_size_max          0.35
_exptl_crystal_size_mid          0.25
_exptl_crystal_size_min          0.16
_refine_diff_density_max         0.750
_refine_diff_density_min         -0.912
_refine_ls_abs_structure_details 'Flack (1983), 718 Friedel pairs'
_refine_ls_abs_structure_Flack   0.019(16)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.032
_refine_ls_matrix_type           full
_refine_ls_number_parameters     159
_refine_ls_number_reflns         1757
_refine_ls_number_restraints     2
_refine_ls_restrained_S_all      1.031
_refine_ls_R_factor_all          0.0408
_refine_ls_R_factor_gt           0.0288
_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^)+(0.0368P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0712
_refine_ls_wR_factor_ref         0.0763
_reflns_number_gt                1516
_reflns_number_total             1757
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            ru2026.cif
_cod_data_source_block           I
_cod_original_cell_volume        1600.4(3)
_cod_database_code               2234381
_cod_database_fobs_code          2234381