(tBu2MeSi)2Sn=Sn(SiMetBu2)2: a distannene with a >Sn=Sn< double bond that is stable both in the solid state and in solution.
Lee, Vladimir Ya; Fukawa, Tomohide; Nakamoto, Masaaki; Sekiguchi, Akira; Tumanskii, Boris L; Karni, Miriam; Apeloig, Yitzhak; Journal of the American Chemical Society 128 (2006) 11643–11651; doi:10.1021/ja063322x

data_4101579
_publ_section_title
;
 (tBu2MeSi)2Sn=Sn(SiMetBu2)2: a distannene with a &gt;Sn=Sn&lt; double
 bond that is stable both in the solid state and in solution.
;
_journal_issue                   35
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              11643
_journal_page_last               11651
_journal_paper_doi               10.1021/ja063322x
_journal_volume                  128
_journal_year                    2006
_chemical_formula_sum            'C44 H90 Si4 Sn2'
_chemical_formula_weight         968.90
_chemical_name_systematic
;
(t-Bu2MeSi)2Sn-Sn(SiMet-Bu2)2C(Ph)=CH
;
_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                75.877(2)
_cell_angle_beta                 87.714(3)
_cell_angle_gamma                68.845(2)
_cell_formula_units_Z            2
_cell_length_a                   11.7250(3)
_cell_length_b                   13.0250(6)
_cell_length_c                   18.7090(8)
_cell_measurement_reflns_used    25788
_cell_measurement_temperature    120
_cell_measurement_theta_max      28.01
_cell_measurement_theta_min      2.13
_cell_volume                     2580.44(18)
_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    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      120
_diffrn_measured_fraction_theta_full 0.911
_diffrn_measured_fraction_theta_max 0.911
_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  0.024
_diffrn_reflns_av_sigmaI/netI    0.0432
_diffrn_reflns_limit_h_max       14
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       17
_diffrn_reflns_limit_k_min       -15
_diffrn_reflns_limit_l_max       24
_diffrn_reflns_limit_l_min       -24
_diffrn_reflns_number            25788
_diffrn_reflns_theta_full        28.01
_diffrn_reflns_theta_max         28.01
_diffrn_reflns_theta_min         2.13
_exptl_absorpt_coefficient_mu    1.087
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            yellow
_exptl_crystal_density_diffrn    1.247
_exptl_crystal_density_meas      ?
_exptl_crystal_density_method    .
_exptl_crystal_description       plate
_exptl_crystal_F_000             1020
_exptl_crystal_size_max          0.40
_exptl_crystal_size_mid          0.10
_exptl_crystal_size_min          0.05
_refine_diff_density_max         0.896
_refine_diff_density_min         -1.270
_refine_diff_density_rms         0.087
_refine_ls_extinction_coef       0.0094(4)
_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   1.034
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     506
_refine_ls_number_reflns         11379
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.034
_refine_ls_R_factor_all          0.0422
_refine_ls_R_factor_gt           0.0335
_refine_ls_shift/su_max          0.002
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0539P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0881
_refine_ls_wR_factor_ref         0.0914
_reflns_number_gt                9339
_reflns_number_total             11379
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ja063322xsi20060512_062506.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_enum 1527 2010-12-29 10:47:43Z saulius 

The following automatic conversions were performed:

'_refine_ls_hydrogen_treatment' value 'constr.' was replaced with the
value 'constr' as specified in the replacement file
'src/cod-tools/trunk/data/replacement-values/replacement_values.lst'.

Automatic conversion script
Id: cif_fix_values 5376 2017-05-30 11:51:03Z andrius 
;
_cod_original_sg_symbol_H-M      'P -1          '
_cod_database_code               4101579