The first example of a molecule-based ferroelectric with barium cation: catena-(μ2-nitrito-O,O)-bi-aqua-(18-crown-6)-barium nitrite
Fu, Da-Wei; Zhang, Yi; Cai, Hong-Ling; Zhu, Hao-miao; Chen, Xue-yuan; Xiong, Ren-Gen; Journal of Materials Chemistry 22 (2012) 17525–; doi:10.1039/c2jm32662k

data_7208615
_publ_section_title
;
 The first example of a molecule-based ferroelectric with barium cation:
 catena-(\m2-nitrito-O,O)-bi-aqua-(18-crown-6)-barium nitrite
;
_journal_issue                   34
_journal_name_full               'Journal of Materials Chemistry'
_journal_page_first              17525
_journal_paper_doi               10.1039/c2jm32662k
_journal_volume                  22
_journal_year                    2012
_chemical_formula_sum            'C12 H28 Ba N2 O12'
_chemical_formula_weight         529.70
_space_group_IT_number           62
_symmetry_space_group_name_Hall  '-P 2ac 2n'
_symmetry_space_group_name_H-M   'P n m a'
_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                   17.573(4)
_cell_length_b                   17.510(4)
_cell_length_c                   6.8305(14)
_cell_measurement_temperature    293(2)
_cell_volume                     2101.8(8)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.995
_diffrn_measured_fraction_theta_max 0.995
_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  0.0845
_diffrn_reflns_av_sigmaI/netI    0.0534
_diffrn_reflns_limit_h_max       22
_diffrn_reflns_limit_h_min       -22
_diffrn_reflns_limit_k_max       22
_diffrn_reflns_limit_k_min       -22
_diffrn_reflns_limit_l_max       8
_diffrn_reflns_limit_l_min       -8
_diffrn_reflns_number            21216
_diffrn_reflns_theta_full        27.47
_diffrn_reflns_theta_max         27.47
_diffrn_reflns_theta_min         2.33
_exptl_absorpt_coefficient_mu    1.948
_exptl_crystal_density_diffrn    1.674
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             1064
_refine_diff_density_max         1.443
_refine_diff_density_min         -1.233
_refine_diff_density_rms         0.197
_refine_ls_extinction_coef       0.037(3)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   1.144
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     143
_refine_ls_number_reflns         2471
_refine_ls_number_restraints     2
_refine_ls_restrained_S_all      1.171
_refine_ls_R_factor_all          0.0737
_refine_ls_R_factor_gt           0.0580
_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^)+(0.0801P)^2^+0.1889P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1420
_refine_ls_wR_factor_ref         0.1541
_reflns_number_gt                1962
_reflns_number_total             2471
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            c2jm32662k.txt
_cod_data_source_block           3
_cod_original_sg_symbol_H-M      'P nma'
_cod_database_code               7208615