New mixed aluminium‒chromium diarsenate
Bouhassine, Mohamad Alem; Boughzala, Habib; Acta Crystallographica Section E 73 (2017) 345–348; doi:10.1107/S2056989017001797

data_2242241
_publ_section_title
;
 New mixed aluminium--chromium diarsenate
;
_journal_coeditor_code           PJ2041
_journal_issue                   3
_journal_name_full               'Acta Crystallographica Section E'
_journal_page_first              345
_journal_page_last               348
_journal_paper_doi               10.1107/S2056989017001797
_journal_volume                  73
_journal_year                    2017
_chemical_formula_iupac          'K Cr0.25 Al0.75 As2 O7'
_chemical_formula_moiety         'Al0.75 As2 Cr0.25 K O7'
_chemical_formula_sum            'Al0.75 As2 Cr0.25 K O7'
_chemical_formula_weight         334.17
_chemical_name_systematic
;
Potassium chromium aluminium diarsenate, KCr~1/4~Al~3/4~As~2~O~7~
;
_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_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                96.57(2)
_cell_angle_beta                 104.45(3)
_cell_angle_gamma                103.08(4)
_cell_formula_units_Z            2
_cell_length_a                   6.243(3)
_cell_length_b                   6.349(3)
_cell_length_c                   8.153(4)
_cell_measurement_reflns_used    25
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      27
_cell_measurement_theta_min      3.8
_cell_volume                     299.8(3)
_computing_cell_refinement
;
CAD-4 EXPRESS (Enraf--Nonius, 1994)
;
_computing_data_collection
;
CAD-4 EXPRESS (Enraf--Nonius, 1994)
;
_computing_data_reduction
;
XCAD4 (Harms & Wocadlo, 1995)
;
_computing_molecular_graphics
;
DIAMOND (Brandenburg, 2008)
;
_computing_publication_material
;
publCIF (Westrip, 2010)
;
_computing_structure_refinement
;
SHELXL97 (Sheldrick, 2008)
;
_computing_structure_solution
;
SHELXS97 (Sheldrick, 2008)
;
_diffrn_ambient_temperature      293(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  0.0136
_diffrn_reflns_av_sigmaI/netI    0.0223
_diffrn_reflns_limit_h_max       7
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -8
_diffrn_reflns_limit_l_max       11
_diffrn_reflns_limit_l_min       -11
_diffrn_reflns_number            1628
_diffrn_reflns_theta_full        29.95
_diffrn_reflns_theta_max         29.95
_diffrn_reflns_theta_min         2.62
_diffrn_standards_decay_%        1.1
_diffrn_standards_interval_time  120
_diffrn_standards_number         2
_exptl_absorpt_coefficient_mu    12.366
_exptl_absorpt_correction_T_max  0.1820
_exptl_absorpt_correction_T_min  0.0788
_exptl_absorpt_correction_type   psi-scan
_exptl_absorpt_process_details
;
(North <i>et al.</i>,  1968)
;
_exptl_crystal_colour            Green
_exptl_crystal_density_diffrn    3.702
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       Triclinic
_exptl_crystal_F_000             314
_exptl_crystal_size_max          0.40
_exptl_crystal_size_mid          0.30
_exptl_crystal_size_min          0.20
_refine_diff_density_max         0.585
_refine_diff_density_min         -1.088
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.081
_refine_ls_matrix_type           full
_refine_ls_number_parameters     104
_refine_ls_number_reflns         1479
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.081
_refine_ls_R_factor_all          0.0286
_refine_ls_R_factor_gt           0.0230
_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^)+(0.0303P)^2^+0.5924P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0566
_refine_ls_wR_factor_ref         0.0586
_reflns_number_gt                1306
_reflns_number_total             1479
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            pj2041sup1.cif
_cod_data_source_block           I
_cod_original_cell_volume        299.8(8)
_cod_original_sg_symbol_Hall     '-p 1'
_cod_database_code               2242241
_cod_database_fobs_code 2242241