First structural evidence for multiple alkali metals between sandwich decks in a metallocene.
Jeletic, Matthew; Perras, Frédéric A; Gorelsky, Serge I.; Le Roy, Jennifer J.; Korobkov, Ilia; Bryce, David L.; Murugesu, Muralee; Dalton transactions (Cambridge, England : 2003) 41 (2012) 8060–8066; doi:10.1039/c2dt30164d

data_7019304
_publ_section_title
;
 First structural evidence for multiple alkali metals between sandwich
 decks in a metallocene.
;
_journal_issue                   26
_journal_name_full
'Dalton transactions (Cambridge, England : 2003)'
_journal_page_first              8060
_journal_page_last               8066
_journal_paper_doi               10.1039/c2dt30164d
_journal_volume                  41
_journal_year                    2012
_chemical_formula_sum            'C22 H40 Na2 O2 Si2'
_chemical_formula_weight         438.70
_chemical_name_systematic
;
?
;
_space_group_IT_number           63
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  '-C 2c 2'
_symmetry_space_group_name_H-M   'C m c m'
_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                   7.3962(2)
_cell_length_b                   20.1718(4)
_cell_length_c                   17.1472(3)
_cell_measurement_reflns_used    9939
_cell_measurement_temperature    200(2)
_cell_measurement_theta_max      28.25
_cell_measurement_theta_min      2.34
_cell_volume                     2558.27(10)
_computing_cell_refinement       'APEX II, Bruker (2009)'
_computing_data_collection       'APEX II, Bruker (2009)'
_computing_data_reduction        'XPREP, Bruker (2009)'
_computing_molecular_graphics    'SHELXTL, Bruker (2004)'
_computing_publication_material  'SHELXTL, Bruker (2004)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      200(2)
_diffrn_measured_fraction_theta_full 0.891
_diffrn_measured_fraction_theta_max 0.891
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_diffrn_measurement_method       '\f and \w scans'
_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  0.0350
_diffrn_reflns_av_sigmaI/netI    0.0183
_diffrn_reflns_limit_h_max       9
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       26
_diffrn_reflns_limit_k_min       -26
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_limit_l_min       -20
_diffrn_reflns_number            20049
_diffrn_reflns_theta_full        28.31
_diffrn_reflns_theta_max         28.31
_diffrn_reflns_theta_min         2.02
_exptl_absorpt_coefficient_mu    0.187
_exptl_absorpt_correction_T_max  0.9725
_exptl_absorpt_correction_T_min  0.9689
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'SADABS, Bruker (2003)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.139
_exptl_crystal_density_meas      ?
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             952
_exptl_crystal_size_max          0.17
_exptl_crystal_size_mid          0.15
_exptl_crystal_size_min          0.15
_refine_diff_density_max         0.384
_refine_diff_density_min         -0.416
_refine_diff_density_rms         0.055
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.043
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     84
_refine_ls_number_reflns         1576
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.043
_refine_ls_R_factor_all          0.0498
_refine_ls_R_factor_gt           0.0399
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0665P)^2^+2.7777P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1110
_refine_ls_wR_factor_ref         0.1192
_reflns_number_gt                1322
_reflns_number_total             1576
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            c2dt30164d.txt
_cod_data_source_block           mm085
_cod_depositor_comments
;
The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Orthorhombic' changed to
'orthorhombic' according to
/home/saulius/struct/CIF-dictionaries/cif_core.dic dictionary named
'cif_core.dic' version 2.4.1 from 2010-06-29.

Automatic conversion script
Id: cif_fix_values 1891 2012-01-12 08:04:46Z andrius 

The following automatic conversions were performed:

'_exptl_crystal_density_meas' value 'n/a' was changed to '?' - the
value is perceived as not measured.

Automatic conversion script
Id: cif_fix_values 3008 2015-01-20 13:52:24Z robertas 
;
_cod_original_sg_symbol_H-M      Cmcm
_cod_database_code               7019304