Aromaticity of the Cyclobutadiene Dianion: Structural Characteristics and Magnetic Properties
Sekiguchi, Akira; Matsuo, Tsukasa; Tanaka, Masanobu; Organometallics 21 (2002) 1072–; doi:10.1021/om010902o

data_4076668
_publ_section_title
;
 Aromaticity of the Cyclobutadiene Dianion:&#x00A0; Structural
 Characteristics and Magnetic Properties
;
_journal_issue                   6
_journal_name_full               Organometallics
_journal_page_first              1072
_journal_paper_doi               10.1021/om010902o
_journal_volume                  21
_journal_year                    2002
_chemical_formula_sum            'C30 H48 Li2 O4 Si2'
_chemical_formula_weight         542.75
_chemical_name_systematic
; 
 1,2-Diphenyl-3,4-bis(trimethylsilylcyclobutadiene 
 bis[1,2-dimethoxyethane(lithium)]  
;
_space_group_IT_number           2
_symmetry_cell_setting           triclinic
_symmetry_space_group_name_Hall  '-P 1'
_symmetry_space_group_name_H-M   'P -1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                74.980(6)
_cell_angle_beta                 70.856(6)
_cell_angle_gamma                63.375(5)
_cell_formula_units_Z            2
_cell_length_a                   11.1150(12)
_cell_length_b                   11.0320(13)
_cell_length_c                   15.6610(11)
_cell_measurement_reflns_used    16195
_cell_measurement_temperature    120
_cell_measurement_theta_max      27.95
_cell_measurement_theta_min      2.35
_cell_volume                     1607.4(3)
_computing_cell_refinement       'HKL scalepack'
_computing_data_collection       'MacScience Xpress'
_computing_data_reduction        Denzo
_computing_molecular_graphics    ORTEP
_computing_publication_material  CIFTAB
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    SIR92
_diffrn_ambient_temperature      120
_diffrn_measured_fraction_theta_full 0.919
_diffrn_measured_fraction_theta_max 0.919
_diffrn_measurement_device_type  'MacScience DIP2030 Image plate'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'rotating anode'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71070
_diffrn_reflns_av_R_equivalents  0.0710
_diffrn_reflns_av_sigmaI/netI    0.0923
_diffrn_reflns_limit_h_max       14
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       14
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       20
_diffrn_reflns_limit_l_min       -18
_diffrn_reflns_number            16195
_diffrn_reflns_theta_full        27.95
_diffrn_reflns_theta_max         27.95
_diffrn_reflns_theta_min         2.35
_exptl_absorpt_coefficient_mu    0.141
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            Yellow-orange
_exptl_crystal_density_diffrn    1.121
_exptl_crystal_density_meas      ?
_exptl_crystal_description       Plate
_exptl_crystal_F_000             588
_exptl_crystal_size_max          0.30
_exptl_crystal_size_mid          0.25
_exptl_crystal_size_min          0.10
_refine_diff_density_max         0.295
_refine_diff_density_min         -0.398
_refine_diff_density_rms         0.073
_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   1.047
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     344
_refine_ls_number_reflns         7089
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.047
_refine_ls_R_factor_all          0.1214
_refine_ls_R_factor_gt           0.0671
_refine_ls_shift/su_max          0.007
_refine_ls_shift/su_mean         0.001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0654P)^2^+1.4645P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1503
_refine_ls_wR_factor_ref         0.1824
_reflns_number_gt                4395
_reflns_number_total             7089
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            om010902o.cif
_cod_data_source_block           shelxl
_cod_depositor_comments
;
The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Triclinic' changed to 'triclinic'
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 1715 2011-07-08 13:25:40Z adriana 

The following automatic conversions were performed:

'_exptl_crystal_density_meas' value 'not measured' 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      'P -1          '
_cod_database_code               4076668