On the nature of non-covalent interactions in isomers of 2,5-dichloro-1,4-benzoquinone dimers - ground- and excited-state properties.
Vijaya Pandiyan, B.; Deepa, P.; Kolandaivel, P.; Physical chemistry chemical physics : PCCP 16 (2014) 19928–19940; doi:10.1039/c4cp02484b

data_7218036
_publ_section_title
;
 On the nature of non-covalent interactions in isomers of
 2,5-dichloro-1,4-benzoquinone dimers - ground- and excited-state
 properties.
;
_journal_issue                   37
_journal_name_full               'Physical chemistry chemical physics : PCCP'
_journal_page_first              19928
_journal_page_last               19940
_journal_paper_doi               10.1039/c4cp02484b
_journal_volume                  16
_journal_year                    2014
_chemical_formula_moiety         'C6 H2 Cl2 O2'
_chemical_formula_sum            'C6 H2 Cl2 O2'
_chemical_formula_weight         176.98
_chemical_name_common            '2,5-dichloro 1,4-benzoquinone'
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_Int_Tables_number      14
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 1'
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_conform_dict_location     ftp://ftp.iucr.org/pub/cif_core.dic
_audit_conform_dict_name         cif_core.dic
_audit_conform_dict_version      2.3
_audit_creation_date             '12-Oct-10 T00:48:47-00:00'
_audit_creation_method           'XD routine XDCIF'
_cell_angle_alpha                90
_cell_angle_beta                 92.604(2)
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   6.0187(3)
_cell_length_b                   5.3451(3)
_cell_length_c                   9.9651(4)
_cell_measurement_reflns_used    1243
_cell_measurement_temperature    90(2)
_cell_measurement_theta_max      50.14
_cell_measurement_theta_min      3.39
_cell_volume                     320.25(3)
_computing_cell_refinement       'SAINTPLUS (BRUKER-AXS)'
_computing_data_collection       'KAPPA APEX II (BRUKER-AXS)'
_computing_data_reduction        'SAINTPLUS (BRUKER-AXS)'
_computing_molecular_graphics    'XD2006 (Volkov et al, 2006)'
_computing_publication_material  'XD2006 (Volkov et al, 2006)'
_computing_structure_refinement  'XD2006 (Volkov et al, 2006)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      90(2)
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.997
_diffrn_measurement_device_type  'Bruker Kappa APEX II CCD detector'
_diffrn_measurement_method       '\f and \w scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_probe          x-ray
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0248
_diffrn_reflns_av_sigmaI/netI    0.0254
_diffrn_reflns_limit_h_max       12
_diffrn_reflns_limit_h_min       -12
_diffrn_reflns_limit_k_max       11
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       21
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            41047
_diffrn_reflns_theta_full        50.14
_diffrn_reflns_theta_max         50.13
_diffrn_reflns_theta_min         2.36
_exptl_absorpt_coefficient_mu    0.931
_exptl_absorpt_correction_T_max  0.8503
_exptl_absorpt_correction_T_min  0.8213
_exptl_absorpt_correction_type   analytical
_exptl_absorpt_process_details   'Bruker AXS, 2008'
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.835
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             176
_exptl_crystal_size_max          0.22
_exptl_crystal_size_mid          0.20
_exptl_crystal_size_min          0.18
_refine_diff_density_max         0.176
_refine_diff_density_min         -0.170
_refine_diff_density_rms         0.034
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.003
_refine_ls_matrix_type           full
_refine_ls_number_parameters     147
_refine_ls_number_reflns         3014
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.003
_refine_ls_R_factor_all          0.0157
_refine_ls_R_factor_gt           0.0116
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef F
_refine_ls_weighting_details
;

calc w2 = 1/[s^2^(Fo^2^)]

;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_ref         0.0160
_reflns_number_gt                3014
_reflns_number_total             3380
_reflns_threshold_expression     >3sigma(I)
_cod_data_source_file            c4cp02484b2.cif
_cod_data_source_block           XB
_cod_depositor_comments
;
The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic'
according to
/usr/data/users/saulius/crontab/automatic-downloads/current/RSC/lib/dictionaries/cif_core.dic
dictionary named 'cif_core.dic' version 2.4.2 from 2011-04-26.

Automatic conversion script
Id: cif_fix_values 2281 2013-09-26 08:29:07Z andrius 
;
_cod_original_sg_symbol_H-M      'P 21/c'
_cod_database_code               7218036
_atom_site_anharm_details
;

The atomic anharmonic pdf is approximated by a Gram-Charlier expansion

about the harmonic pdf, according to the expression :

P(u) = (1 + Cijk*Hijk/3! + Dijkl*Hijkl/4!)*P(0)

The coefficients Cijk and Dijkl are refined in the least squares procedure.

The reported coefficients Cijk are multiplied by 1000 and Dijkl by 10000.

;