Identification and optical features of the Pb4Ln2O7 series (Ln = La, Gd, Sm, Nd), genuine 2D-van der Waals oxides.
Colmont, Marie; Lemoine, Kevin; Roussel, Pascal; Kabbour, Houria; Olchowka, Jacob; Henry, Natacha; Hagemann, Hans; Mentré, Olivier; Chemical Communications  (2019) –; doi:10.1039/C8CC07707J

data_7122920
_publ_section_title
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 Identification and optical features of the Pb4Ln2O7 series (Ln = La, Gd,
 Sm, Nd), genuine 2D-van der Waals oxides.
;
_journal_name_full               'Chemical Communications'
_journal_paper_doi               10.1039/C8CC07707J
_journal_year                    2019
_chemical_formula_moiety         'La2 O7 Pb4'
_chemical_formula_sum            'La2 O7 Pb4'
_chemical_formula_weight         1218.61
_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   difmap
_atom_sites_solution_primary     direct
_audit_update_record
;
2018-09-25 deposited with the CCDC.
2019-01-31 downloaded from the CCDC.
;
_cell_angle_alpha                72.574(10)
_cell_angle_beta                 84.285(10)
_cell_angle_gamma                61.737(10)
_cell_formula_units_Z            2
_cell_length_a                   7.7054(10)
_cell_length_b                   7.7262(10)
_cell_length_c                   10.1822(10)
_cell_measurement_reflns_used    9593
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      26.29
_cell_measurement_theta_min      3.01
_cell_volume                     508.77(12)
_computing_cell_refinement       'USER DEFINED CELL REFINEMENT'
_computing_data_collection       'USER DEFINED DATA COLLECTION'
_computing_data_reduction        'USER DEFINED DATA REDUCTION'
_computing_molecular_graphics    'CAMERON (Watkin et al., 1996)'
_computing_publication_material  'CRYSTALS (Betteridge et al., 2003)'
_computing_structure_refinement  'CRYSTALS (Betteridge et al., 2003)'
_computing_structure_solution    'SHELXS 86 (Sheldrick, 1986)'
_diffrn_ambient_temperature      293
_diffrn_measured_fraction_theta_full 0.977
_diffrn_measured_fraction_theta_max 0.971
_diffrn_measurement_device       Serial
_diffrn_measurement_device_type  'Bruker SMART APEX2 area detector'
_diffrn_measurement_method       '\w and \f scans'
_diffrn_radiation_monochromator  'mirror optics'
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.050
_diffrn_reflns_limit_h_max       9
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       9
_diffrn_reflns_limit_k_min       -8
_diffrn_reflns_limit_l_max       12
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            2046
_diffrn_reflns_theta_full        25.930
_diffrn_reflns_theta_max         26.459
_diffrn_reflns_theta_min         2.099
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    74.151
_exptl_absorpt_correction_T_max  1.0000
_exptl_absorpt_correction_T_min  0.3922
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
SADABS-2012/1 (Bruker,2012) was used for absorption correction.
wR2(int) was 0.1722 before and 0.0793 after correction.
The Ratio of minimum to maximum transmission is 0.3922.
The \l/2 correction factor is 0.0015.
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    7.954
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             996
_exptl_crystal_size_max          0.126
_exptl_crystal_size_mid          0.095
_exptl_crystal_size_min          0.005
_refine_diff_density_max         7.04
_refine_diff_density_min         -4.45
_refine_ls_extinction_coef       0.77(19)
_refine_ls_extinction_method     'Larson (1970), Equation 22'
_refine_ls_goodness_of_fit_ref   0.9535
_refine_ls_hydrogen_treatment    noref
_refine_ls_matrix_type           full
_refine_ls_number_parameters     84
_refine_ls_number_reflns         1707
_refine_ls_number_restraints     0
_refine_ls_R_factor_all          0.0518
_refine_ls_R_factor_gt           0.0465
_refine_ls_shift/su_max          0.0004404
_refine_ls_shift/su_mean         0.0000431
_refine_ls_structure_factor_coef F
_refine_ls_weighting_details
;
 Method, part 1, Chebychev polynomial, (Watkin, 1994, Prince, 1982) 
 [weight] = 1.0/[A~0~*T~0~(x)+A~1~*T~1~(x) ... +A~n-1~]*T~n-1~(x)] 
 where A~i~ are the Chebychev coefficients listed below and x= Fcalc/Fmax 
 Method = Robust Weighting (Prince, 1982) 
 W = [weight] * [1-(deltaF/6*sigmaF)^2^]^2^ 
 A~i~ are: 
 0.517 0.410 0.345 
;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_all         0.0437
_refine_ls_wR_factor_gt          0.0405
_refine_ls_wR_factor_ref         0.0401
_reflns_limit_h_max              9
_reflns_limit_h_min              -9
_reflns_limit_k_max              9
_reflns_limit_k_min              -8
_reflns_limit_l_max              12
_reflns_limit_l_min              0
_reflns_number_gt                1780
_reflns_number_total             2046
_reflns_threshold_expression     I>2.0\s(I)
_oxford_diffrn_Wilson_B_factor   0.00
_oxford_diffrn_Wilson_scale      0.00
_oxford_refine_ls_r_factor_ref   0.0454
_oxford_refine_ls_scale          0.04358(13)
_oxford_reflns_number_all        2038
_oxford_reflns_threshold_expression_ref I>0.0\s(I)
_cod_data_source_file            c8cc07707j2.cif
_cod_data_source_block           1
_cod_original_sg_symbol_H-M      'P -1 '
_cod_database_code               7122920
_iucr_refine_instruction_details_constraints
;
BLOCK 
CONT SCALE 
CONT PB   (    1 ,X'S,U'S)  UNTIL LA   (    2 ) 
CONT O    (    3 ,X'S,U[ISO]) 
CONT LA   (    4 ,X'S,U'S)  UNTIL PB   (    5 ) 
CONT O    (    6 ,X'S,U[ISO])  UNTIL O    (    7 ) 
CONT PB   (    8 ,X'S,U'S) 
CONT O    (    9 ,X'S,U[ISO])  UNTIL O    (   11 ) 
CONT PB   (   12 ,X'S,U'S) 
CONT O    (   13 ,X'S,U[ISO]) 
CONT EXTPARAM 
END                                                                             
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_iucr_refine_instruction_details_restraints
;
NO 
REM   HREST   START (DO NOT REMOVE THIS LINE) 
REM   HREST   END (DO NOT REMOVE THIS LINE) 
END                                                                             
;