Rb<sub>2</sub>Ca<sub>2</sub>Si<sub>2</sub>O<sub>7</sub>: a new alkali alkaline-earth silicate based on [Si<sub>2</sub>O<sub>7</sub>]<sup>6-</sup> anions.
Kahlenberg, Volker; Acta crystallographica. Section C, Structural chemistry 81 (2025) 146–155; doi:10.1107/S2053229625001196

data_2312757
_publ_section_title
;
 Rb<sub>2</sub>Ca<sub>2</sub>Si<sub>2</sub>O<sub>7</sub>: a new alkali
 alkaline-earth silicate based on
 [Si<sub>2</sub>O<sub>7</sub>]<sup>6-</sup> anions.
;
_journal_coeditor_code           EF3065
_journal_issue                   'Pt 3'
_journal_name_full
'Acta crystallographica. Section C, Structural chemistry'
_journal_page_first              146
_journal_page_last               155
_journal_paper_doi               10.1107/S2053229625001196
_journal_volume                  81
_journal_year                    2025
_chemical_formula_iupac          'Rb2 Ca2 Si2 O7'
_chemical_formula_sum            'Ca2 O7 Rb2 Si2'
_chemical_formula_weight         419.28
_chemical_name_systematic
;
Dirubidium dicalcium pyrosilicate
;
_space_group_IT_number           59
_space_group_name_Hall           '-P 2ab 2a'
_space_group_name_H-M_alt        'P m m n :2'
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_H-M   'P m m n :2'
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_conform_dict_name         cif_core.dic
_audit_conform_dict_version      2.4.3
_audit_creation_method           'WinGX routine CIF_UPDATE'
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   5.7363(6)
_cell_length_b                   13.8532(12)
_cell_length_c                   9.9330(10)
_cell_measurement_reflns_used    2256
_cell_measurement_temperature    288(2)
_cell_measurement_theta_max      29.495
_cell_measurement_theta_min      5.002
_cell_volume                     789.34(13)
_computing_cell_refinement
;
CrysAlis PRO (Rigaku OD, 2020)
;
_computing_data_collection
;
CrysAlis PRO (Rigaku OD, 2020)
;
_computing_data_reduction
;
CrysAlis PRO (Rigaku OD, 2020)
;
_computing_structure_refinement
;
SHELXL97 (Sheldrick, 2008)
;
_computing_structure_solution
;
SIR2002 (Burla <i>et al.</i>,  2003)
;
_diffrn_ambient_temperature      288(2)
_diffrn_detector                 'CCD plate'
_diffrn_detector_area_resol_mean 10.3575
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.997
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type  'Xcalibur, Ruby, Gemini ultra'
_diffrn_measurement_method       '\w scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0584
_diffrn_reflns_av_unetI/netI     0.0232
_diffrn_reflns_limit_h_max       7
_diffrn_reflns_limit_h_min       -7
_diffrn_reflns_limit_k_max       17
_diffrn_reflns_limit_k_min       -17
_diffrn_reflns_limit_l_max       12
_diffrn_reflns_limit_l_min       -12
_diffrn_reflns_number            10834
_diffrn_reflns_theta_full        26.35
_diffrn_reflns_theta_max         26.35
_diffrn_reflns_theta_min         3.59
_diffrn_source                   'fine-focus sealed X-ray tube'
_exptl_absorpt_coefficient_mu    14
_exptl_absorpt_correction_T_max  0.678
_exptl_absorpt_correction_T_min  0.121
_exptl_absorpt_correction_type   analytical
_exptl_absorpt_process_details
;
[CrysAlis PRO (Rigaku OD, 2020), based on expressions derived by Clark &
Reid (1995)]
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    3.528
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       'thin plate'
_exptl_crystal_F_000             792
_exptl_crystal_size_max          0.323
_exptl_crystal_size_mid          0.1
_exptl_crystal_size_min          0.036
_refine_diff_density_max         0.862
_refine_diff_density_min         -0.696
_refine_ls_extinction_coef       0.0100(5)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method
;
SHELXL97 (Sheldrick, 2008)
;
_refine_ls_goodness_of_fit_ref   1.057
_refine_ls_matrix_type           full
_refine_ls_number_parameters     78
_refine_ls_number_reflns         931
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.057
_refine_ls_R_factor_all          0.0395
_refine_ls_R_factor_gt           0.0299
_refine_ls_shift/su_max          0
_refine_ls_shift/su_mean         0
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0295P)^2^+3.6732P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0717
_refine_ls_wR_factor_ref         0.0761
_reflns_number_gt                773
_reflns_number_total             931
_reflns_threshold_expression     >2\s(I)
_cod_data_source_file            ef3065.cif
_cod_data_source_block           RT
_cod_depositor_comments
'Adding full bibliography for 2312757--2312758.cif.'
_cod_original_sg_symbol_H-M      'P m m n'
_cod_database_code               2312757