With regard to the hydrogen bonding in complexes of pyridylureas, less is more. a role for shape complementarity and CH...O interactions?
Quinn, Jordan R.; Zimmerman, Steven C.; Organic letters 6 (2004) 1649–1652; doi:10.1021/ol0495016

data_1507098
_publ_contact_author
; 
Steven C. Zimmerman 
University of Illinois 
Department of Chemistry, MC-712 
600 South Mathews Avenue 
Urbana, Illinois  61801 
USA 
;
_publ_section_title
;
 With regard to the hydrogen bonding in complexes of pyridylureas, less is
 more. a role for shape complementarity and CH...O interactions?
;
_journal_issue                   10
_journal_name_full               'Organic letters'
_journal_page_first              1649
_journal_page_last               1652
_journal_paper_doi               10.1021/ol0495016
_journal_volume                  6
_journal_year                    2004
_chemical_formula_moiety         'C18 H14 N4 O2, C4 H8 O'
_chemical_formula_sum            'C22 H22 N4 O3'
_chemical_formula_weight         390.44
_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'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_audit_update_record
; 
2003-12-16   text and data added, srw 
;
_cell_angle_alpha                90.00
_cell_angle_beta                 110.099(4)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   11.785(4)
_cell_length_b                   12.738(4)
_cell_length_c                   14.103(4)
_cell_measurement_reflns_used    918
_cell_measurement_temperature    193(2)
_cell_measurement_theta_max      28.1
_cell_measurement_theta_min      2.4
_cell_volume                     1988.2(11)
_computing_cell_refinement       'SAINT V6.22 (Bruker, 2001)'
_computing_data_collection       'SMART V5.625 (Bruker, 2001)'
_computing_data_reduction        'SAINT V6.22 (Bruker, 2001)'
_computing_molecular_graphics    'SHELXTL V6.10 (Bruker, 2001)'
_computing_publication_material  'CIFTAB (Sheldrick, 2001)'
_computing_structure_refinement  'SHELXTL V6.10 (Bruker, 2001)'
_computing_structure_solution    'SHELXTL V6.10 (Bruker, 2001)'
_diffrn_ambient_temperature      193(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device       'Siemens Platform/CCD'
_diffrn_measurement_method       'profile data from \w scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'normal-focus sealed tube'
_diffrn_radiation_type           MoK\a
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_diffrn_radiation_wavelength_id  p19zas
_diffrn_reflns_av_R_equivalents  0.0398
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_diffrn_reflns_limit_h_max       14
_diffrn_reflns_limit_h_min       -14
_diffrn_reflns_limit_k_max       15
_diffrn_reflns_limit_k_min       -15
_diffrn_reflns_limit_l_max       16
_diffrn_reflns_limit_l_min       -16
_diffrn_reflns_number            15739
_diffrn_reflns_theta_full        25.36
_diffrn_reflns_theta_max         25.36
_diffrn_reflns_theta_min         1.84
_diffrn_standards_decay_%        2.9
_diffrn_standards_interval_time  205
_diffrn_standards_number         173
_exptl_absorpt_coefficient_mu    0.089
_exptl_absorpt_correction_T_max  0.9839
_exptl_absorpt_correction_T_min  0.9372
_exptl_absorpt_correction_type   integration
_exptl_absorpt_process_details   '(Bruker, 2001)'
_exptl_crystal_colour            yellow
_exptl_crystal_density_diffrn    1.304
_exptl_crystal_density_meas      ?
_exptl_crystal_description       columnar
_exptl_crystal_F_000             824
_exptl_crystal_id                p19zas
_exptl_crystal_preparation
; 
The data crystal was mounted using oil (Parantone-N, Exxon) to a 
0.5 mm cryo-loop (Hampton Research) with the (0 0 -1) scattering planes 
roughly normal to the spindle axis. 
;
_exptl_crystal_size_max          0.60
_exptl_crystal_size_mid          0.28
_exptl_crystal_size_min          0.20
_refine_diff_density_max         0.253
_refine_diff_density_min         -0.218
_refine_diff_density_rms         0.043
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.047
_refine_ls_hydrogen_treatment    noref
_refine_ls_matrix_type           full
_refine_ls_number_parameters     315
_refine_ls_number_reflns         3635
_refine_ls_number_restraints     172
_refine_ls_restrained_S_all      1.093
_refine_ls_R_factor_all          0.0779
_refine_ls_R_factor_gt           0.0498
_refine_ls_shift/su_max          0.004
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0712P)^2^+0.5111P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1254
_refine_ls_wR_factor_ref         0.1408
_reflns_number_gt                2502
_reflns_number_total             3635
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol0495016si20040316_094950.cif
_cod_data_source_block           p19zas
_cod_depositor_comments
;
The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic'
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_values 1715 2011-07-08 13:25:40Z adriana 

The following automatic conversions were performed:

'_exptl_crystal_density_meas' value 'not measured' was changed to '?'
- the value is perceived as not measured.

Automatic conversion script
Id: cif_fix_values 3008 2015-01-20 13:52:24Z robertas 
;
_cod_original_cell_volume        1988.2(10)
_cod_original_sg_symbol_Hall     '-P 2ybc '
_cod_original_sg_symbol_H-M      'P 21/c '
_cod_database_code               1507098