Experimental verification of a subtle low-temperature phase transition suggested by DFT-D energy minimisation
Bond, Andrew D.; Solanko, Katarzyna A.; van de Streek, Jacco; Neumann, Marcus A.; CrystEngComm 13 (2011) 1768–; doi:10.1039/c0ce00676a

data_7210531
_publ_section_title
;
 Experimental verification of a subtle low-temperature phase transition
 suggested by DFT-D energy minimisation
;
_journal_issue                   6
_journal_name_full               CrystEngComm
_journal_page_first              1768
_journal_paper_doi               10.1039/c0ce00676a
_journal_volume                  13
_journal_year                    2011
_chemical_formula_moiety         'C20 H14 Cl4 O'
_chemical_formula_sum            'C20 H14 Cl4 O'
_chemical_formula_weight         412.11
_chemical_name_common            2,6-bis(2,4-dichlorobenzylidene)cyclohexanone
_space_group_IT_number           61
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  '-P 2ac 2ab'
_symmetry_space_group_name_H-M   'P b c a'
_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            8
_cell_length_a                   14.4059(11)
_cell_length_b                   7.9797(3)
_cell_length_c                   31.467(2)
_cell_measurement_reflns_used    2999
_cell_measurement_temperature    250(2)
_cell_measurement_theta_max      23.57
_cell_measurement_theta_min      2.59
_cell_volume                     3617.3(4)
_computing_cell_refinement       'SAINT v.7.68a (Bruker, 2010)'
_computing_data_collection       'APEX2 v2010.1-2 (Bruker, 2010)'
_computing_data_reduction        SAINT
_computing_molecular_graphics    SHELXTL
_computing_publication_material  SHELXTL
_computing_structure_refinement  SHELXTL
_computing_structure_solution    'SHELXTL v.6.12 (Sheldrick, 2008)'
_diffrn_ambient_temperature      250(2)
_diffrn_measured_fraction_theta_full 0.985
_diffrn_measured_fraction_theta_max 0.985
_diffrn_measurement_device_type  'Bruker Nonius X8APEX-II CCD'
_diffrn_measurement_method       '\w and \f 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  0.0615
_diffrn_reflns_av_sigmaI/netI    0.0500
_diffrn_reflns_limit_h_max       17
_diffrn_reflns_limit_h_min       -17
_diffrn_reflns_limit_k_max       6
_diffrn_reflns_limit_k_min       -9
_diffrn_reflns_limit_l_max       37
_diffrn_reflns_limit_l_min       -37
_diffrn_reflns_number            21985
_diffrn_reflns_theta_full        25.03
_diffrn_reflns_theta_max         25.03
_diffrn_reflns_theta_min         3.81
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.660
_exptl_absorpt_correction_T_max  0.974
_exptl_absorpt_correction_T_min  0.000
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'SADABS (Sheldrick, 2008)'
_exptl_crystal_colour            yellow
_exptl_crystal_density_diffrn    1.513
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       lath
_exptl_crystal_F_000             1680
_exptl_crystal_size_max          0.20
_exptl_crystal_size_mid          0.08
_exptl_crystal_size_min          0.04
_refine_diff_density_max         0.223
_refine_diff_density_min         -0.332
_refine_diff_density_rms         0.050
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.020
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     226
_refine_ls_number_reflns         3157
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.020
_refine_ls_R_factor_all          0.0817
_refine_ls_R_factor_gt           0.0400
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0253P)^2^+1.8806P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0705
_refine_ls_wR_factor_ref         0.0839
_reflns_number_gt                2068
_reflns_number_total             3157
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            c0ce00676a.txt
_cod_data_source_block           250K
_cod_database_code               7210531