Refinement of the crystal structures of the tetrahedro-tetrasilicides K~4~Si~4~, Rb~4~Si~4~ and Cs~4~Si~4~
von Schnering, H. G.; Schwarz, M.; Chang, J.-H.; Peters, K.; Peters, E.-M.; Nesper, R.; Zeitschrift für Kristallographie - New Crystal Structures 220 (2005) 525–527; doi:

data_8102921
_publ_section_title
;
Refinement of the crystal structures of the tetrahedro-tetrasilicides 
K~4~Si~4~, Rb~4~Si~4~ and Cs~4~Si~4~
;
_journal_issue                   4
_journal_name_full
'Zeitschrift f\"ur Kristallographie - New Crystal Structures'
_journal_page_first              525
_journal_page_last               527
_journal_volume                  220
_journal_year                    2005
_chemical_formula_sum            'K4 Si4'
_chemical_formula_weight         268.74
_chemical_name_systematic
; 
 tetrapotassium tetrahedro-tetrasilicide 
;
_space_group_IT_number           218
_symmetry_cell_setting           cubic
_symmetry_space_group_name_Hall  'P -4n 2 3'
_symmetry_space_group_name_H-M   'P -4 3 n'
_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            8
_cell_length_a                   12.620(1)
_cell_length_b                   12.620(1)
_cell_length_c                   12.620(1)
_cell_measurement_temperature    293(2)
_cell_volume                     2009.9(3)
_computing_molecular_graphics    'Atoms 6.0 [11]'
_computing_structure_refinement  'SHELXL-97 [10] (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 [10] (Sheldrick, 1990)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.947
_diffrn_measured_fraction_theta_max 0.947
_diffrn_measurement_device_type  'Syntex P-1'
_diffrn_measurement_method       omega/2theta
_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  0.0296
_diffrn_reflns_av_sigmaI/netI    0.0202
_diffrn_reflns_limit_h_max       16
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       16
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       16
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            2042
_diffrn_reflns_theta_full        27.51
_diffrn_reflns_theta_max         27.51
_diffrn_reflns_theta_min         2.28
_exptl_absorpt_coefficient_mu    2.165
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   '11 hkl, Psi-Scan'
_exptl_crystal_colour            'black shiny'
_exptl_crystal_density_diffrn    1.776
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       '{100} and {110}'
_exptl_crystal_F_000             1056
_exptl_crystal_size_max          0.5
_exptl_crystal_size_mid          0.5
_exptl_crystal_size_min          0.5
_refine_diff_density_max         0.270
_refine_diff_density_min         -0.157
_refine_diff_density_rms         0.042
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.10(9)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.999
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     25
_refine_ls_number_reflns         425
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.999
_refine_ls_R_factor_all          0.0209
_refine_ls_R_factor_gt           0.0172
_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^)+(0.0257P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0401
_refine_ls_wR_factor_ref         0.0414
_reflns_number_gt                403
_reflns_number_total             425
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            409852.cff
_cod_data_source_block           ksi
_cod_original_sg_symbol_H-M      P-43n
_cod_database_code               8102921