Formation of Nets of Corner-Shared Bicapped Gold Squares in SrAu3Ge: How a BaAl4- Type Derivative Reconciles Fewer Valence Electrons and the Origin of Its Uniaxial Negative Thermal Expansion
Qisheng Lin; John D Corbett; Journal of the American Chemical Society 134 (2012) 4877–4884; doi:10.1021/ja211625w

data_4117646
_publ_section_title
;
 Formation of Nets of Corner-Shared Bicapped Gold Squares in SrAu3Ge: How
 a BaAl4- Type Derivative Reconciles Fewer Valence Electrons and the
 Origin of Its Uniaxial Negative Thermal Expansion
;
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              4877
_journal_page_last               4884
_journal_paper_doi               10.1021/ja211625w
_journal_volume                  134
_journal_year                    2012
_chemical_formula_sum            'Au3 Ge Sr'
_chemical_formula_weight         751.11
_chemical_name_systematic
; 
 ? 
;
_space_group_IT_number           129
_symmetry_cell_setting           tetragonal
_symmetry_space_group_name_Hall  '-P 4a 2a'
_symmetry_space_group_name_H-M   'P 4/n m m :2'
_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            2
_cell_length_a                   6.2638(10)
_cell_length_b                   6.2638(10)
_cell_length_c                   5.5082(9)
_cell_measurement_reflns_used    1231
_cell_measurement_temperature    173(2)
_cell_measurement_theta_max      28.15
_cell_measurement_theta_min      3.70
_cell_volume                     216.12(6)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      173(2)
_diffrn_measured_fraction_theta_full 0.994
_diffrn_measured_fraction_theta_max 0.994
_diffrn_measurement_device_type  'smart apex ccd'
_diffrn_measurement_method       w/
_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  0.0404
_diffrn_reflns_av_sigmaI/netI    0.0249
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       -7
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -5
_diffrn_reflns_limit_l_max       7
_diffrn_reflns_limit_l_min       -7
_diffrn_reflns_number            1231
_diffrn_reflns_theta_full        28.15
_diffrn_reflns_theta_max         28.15
_diffrn_reflns_theta_min         3.70
_exptl_absorpt_coefficient_mu    120.287
_exptl_absorpt_correction_T_max  0.182
_exptl_absorpt_correction_T_min  0.063
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   SADABS
_exptl_crystal_density_diffrn    11.533
_exptl_crystal_F_000             614
_exptl_crystal_size_max          0.026
_exptl_crystal_size_mid          0.020
_exptl_crystal_size_min          0.014
_refine_diff_density_max         2.013
_refine_diff_density_min         -1.975
_refine_diff_density_rms         0.590
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.223
_refine_ls_matrix_type           full
_refine_ls_number_parameters     13
_refine_ls_number_reflns         174
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.223
_refine_ls_R_factor_all          0.0284
_refine_ls_R_factor_gt           0.0223
_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^)+(0.0247P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0499
_refine_ls_wR_factor_ref         0.0511
_reflns_number_gt                156
_reflns_number_total             174
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ja211625w_si_002_2.cif
_cod_data_source_block           SrAu3Ge_173K
_cod_original_sg_symbol_H-M      'P 4/n m m'
_cod_database_code               4117646