The hexamethylpentalene dianion and other reagents for organometallic pentalene chemistry.
Ashley, Andrew E; Cowley, Andrew R; O'Hare, Dermot; Chemical communications (Cambridge, England)  (2007) 1512–1514; doi:10.1039/b702150j

data_7101844
_publ_section_title
;
 The hexamethylpentalene dianion and other reagents for organometallic
 pentalene chemistry.
;
_journal_issue                   15
_journal_name_full
'Chemical communications (Cambridge, England)'
_journal_page_first              1512
_journal_page_last               1514
_journal_paper_doi               10.1039/b702150j
_journal_year                    2007
_chemical_compound_source
;
synthesis as described
;
_chemical_formula_moiety         ' C20 H36 Sn2 '
_chemical_formula_sum            'C20 H36 Sn2'
_chemical_formula_weight         513.89
_chemical_name_systematic
;
?
;
_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
_cell_angle_alpha                99.4761(7)
_cell_angle_beta                 101.8991(7)
_cell_angle_gamma                102.8466(7)
_cell_formula_units_Z            2
_cell_length_a                   7.8927(2)
_cell_length_b                   10.0097(2)
_cell_length_c                   14.9792(3)
_cell_measurement_reflns_used    16301
_cell_measurement_temperature    150
_cell_measurement_theta_max      28
_cell_measurement_theta_min      5
_cell_volume                     1101.18(4)
_computing_cell_refinement
;
KappaCCD software 'DENZO' (Otwinowski & Minor, 1996)
;
_computing_data_collection
;
KappaCCD software 'Collect' (Nonius, 2000)
;
_computing_data_reduction
;
KappaCCD software 'DENZO' (Otwinowski & Minor, 1996)
;
_computing_publication_material
;
CRYSTALS (Watkin et al, 2001)
;
_computing_structure_refinement
;
CRYSTALS (Watkin et al, 2001)
;
_computing_structure_solution    'SIR92 (Giacovazzo et al, 1992)'
_diffrn_ambient_temperature      150
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.997
_diffrn_measurement_device_type
;
Nonius KappaCCD
;
_diffrn_measurement_method       \w
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.024
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            16301
_diffrn_reflns_theta_full        27.532
_diffrn_reflns_theta_max         27.532
_diffrn_reflns_theta_min         5.129
_diffrn_standards_decay_%        0.00
_diffrn_standards_interval_count 0
_diffrn_standards_interval_time  0
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    2.265
_exptl_absorpt_correction_T_max  0.67
_exptl_absorpt_correction_T_min  0.58
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
Denzo/Scalepack (Otwinowski & Minor, 1996)
;
_exptl_crystal_colour            ' pale yellow '
_exptl_crystal_density_diffrn    1.550
_exptl_crystal_description       ' prism '
_exptl_crystal_F_000             512
_exptl_crystal_size_max          0.24
_exptl_crystal_size_mid          0.18
_exptl_crystal_size_min          0.18
_exptl_crystal_thermal_history
;
The material was crystallised at ambient temperature. A suitable crystal
was cooled rapidly to 150K for single-crystal X-ray diffraction analysis.
;
_refine_diff_density_max         0.88
_refine_diff_density_min         -0.78
_refine_ls_extinction_method     None
_refine_ls_goodness_of_fit_ref   1.0405
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     271
_refine_ls_number_reflns         4143
_refine_ls_number_restraints     54
_refine_ls_R_factor_all          0.0315
_refine_ls_R_factor_gt           0.0246
_refine_ls_shift/su_max          0.036881
_refine_ls_structure_factor_coef F
_refine_ls_weighting_details
;
Method, part 1, Chebychev polynomial, (Watkin, 1994, Prince, 1982)
[weight] = 1.0/[A~0~*T~0~(x)+A~1~*T~1~(x) ... +A~n-1~]*T~n-1~(x)]
where A~i~ are the Chebychev coefficients listed below and x= Fcalc/Fmax
Method = Robust Weighting (Prince, 1982)
W = [weight] * [1-(deltaF/6*sigmaF)^2^]^2^
A~i~ are:
0.505 0.212 0.263
;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_all         0.0349
_refine_ls_wR_factor_gt          0.0290
_refine_ls_wR_factor_ref         0.0290
_reflns_limit_h_max              9
_reflns_limit_h_min              -10
_reflns_limit_k_max              12
_reflns_limit_k_min              -12
_reflns_limit_l_max              19
_reflns_limit_l_min              0
_reflns_number_gt                4143
_reflns_number_total             5011
_reflns_threshold_expression     I>3.00u(I)
_cod_data_source_file            b702150j.txt
_cod_data_source_block           arc1447
_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 
;
_cod_original_sg_symbol_H-M      'P -1 '
_cod_original_formula_sum        ' C20 H36 Sn2 '
_cod_database_code               7101844