Pseudosymmetry and phase transition in dimethyl 2,3-bis(tricyclo[3.3.1.1^3,7^]dec-2-ylidene)butanedioate
Bats, Jan W.; Grundl, Marc A.; Hashmi, A. Stephen K.; Acta Crystallographica Section C 57 (2001) 653–656; doi:10.1107/S0108270101003845

data_2011993
_publ_section_title
;
 Pseudosymmetry and phase transition in dimethyl
 2,3-bis(tricyclo[3.3.1.1^3,7^]dec-2-ylidene)butanedioate
;
_journal_issue                   5
_journal_name_full               'Acta Crystallographica Section C'
_journal_page_first              653
_journal_page_last               656
_journal_paper_doi               10.1107/S0108270101003845
_journal_volume                  57
_journal_year                    2001
_chemical_formula_moiety         'C26 H34 O4'
_chemical_formula_sum            'C26 H34 O4'
_chemical_formula_weight         410.53
_chemical_name_systematic
;
dimethyl 2,3-bis(tricyclo[3.3.1.1^3,7^]dec-2-ylidene)butanedioate
;
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 1'
_audit_creation_method           SHELXL97
_cell_angle_alpha                90
_cell_angle_beta                 91.086(12)
_cell_angle_gamma                90
_cell_formula_units_Z            8
_cell_length_a                   13.5686(9)
_cell_length_b                   16.0982(18)
_cell_length_c                   19.615(3)
_cell_measurement_reflns_used    318
_cell_measurement_temperature    204(2)
_cell_measurement_theta_max      23
_cell_measurement_theta_min      3
_cell_volume                     4283.7(9)
_computing_cell_refinement       SMART
_computing_data_collection       'SMART (Siemens, 1995)'
_computing_data_reduction        'SAINT (Siemens, 1995)'
_computing_molecular_graphics    'XP in SHELXTL (Sheldrick, 1996)'
_computing_publication_material  SHELXL97
_computing_structure_refinement  'SHELXL97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      204(2)
_diffrn_measured_fraction_theta_full .994
_diffrn_measured_fraction_theta_max .958
_diffrn_measurement_device_type  'Siemens SMART'
_diffrn_measurement_method       \w
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'normal-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     .71073
_diffrn_reflns_av_R_equivalents  .052
_diffrn_reflns_av_sigmaI/netI    .033
_diffrn_reflns_limit_h_max       18
_diffrn_reflns_limit_h_min       -18
_diffrn_reflns_limit_k_max       22
_diffrn_reflns_limit_k_min       -20
_diffrn_reflns_limit_l_max       26
_diffrn_reflns_limit_l_min       -27
_diffrn_reflns_number            74545
_diffrn_reflns_theta_full        29.00
_diffrn_reflns_theta_max         30.03
_diffrn_reflns_theta_min         1.96
_diffrn_standards_decay_%        .0
_diffrn_standards_interval_time  600
_diffrn_standards_number         708
_exptl_absorpt_coefficient_mu    .084
_exptl_absorpt_correction_T_max  .971
_exptl_absorpt_correction_T_min  .959
_exptl_absorpt_correction_type   numerical
_exptl_absorpt_process_details   'using six faces (SHELXTL; Sheldrick, 1996)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.273
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             1776
_exptl_crystal_size_max          .52
_exptl_crystal_size_mid          .44
_exptl_crystal_size_min          .40
_refine_diff_density_max         .55
_refine_diff_density_min         -.26
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.138
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     545
_refine_ls_number_reflns         12064
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.138
_refine_ls_R_factor_all          .101
_refine_ls_R_factor_gt           .059
_refine_ls_shift/su_max          <0.001
_refine_ls_shift/su_mean         .000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w = 1/[\s^2^(Fo^2^)+(0.06P)^2^+1.3P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_ref         .159
_reflns_number_gt                7584
_reflns_number_total             12064
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            sk1459.cif
_cod_data_source_block           I_at_204K
_cod_original_cell_volume        4283.7(8)
_cod_original_sg_symbol_H-M      'P 21/c'
_cod_database_code               2011993
_cod_database_fobs_code          2011993