Hydrogen Bonding in Crystal Structures ofN,N‘-Bis(3-pyridyl)urea. Why Is the N−H···O Tape Synthon Absent in Diaryl Ureas with Electron-Withdrawing Groups?
Reddy, L. Sreenivas; Basavoju, Srinivas; Vangala, Venu R.; Nangia, Ashwini; Crystal Growth & Design 6 (2006) 161–; doi:10.1021/cg0580152

data_4504808
_publ_section_title
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 Hydrogen Bonding in Crystal Structures ofN,N&#x2018;-Bis(3-pyridyl)urea.
 Why Is the N&#x2212;H&#x00B7;&#x00B7;&#x00B7;O Tape Synthon Absent in
 Diaryl Ureas with Electron-Withdrawing Groups?
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_journal_issue                   1
_journal_name_full               'Crystal Growth &amp; Design'
_journal_page_first              161
_journal_paper_doi               10.1021/cg0580152
_journal_volume                  6
_journal_year                    2006
_chemical_formula_moiety         'C13 H16 N4 O, 2(I)'
_chemical_formula_sum            'C13 H16 I2 N4 O'
_chemical_formula_weight         498.10
_chemical_melting_point          527
_chemical_name_systematic
; 
1,3-bis(3-N-methylpyridinium)urea diiodide 
;
_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
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                101.42(3)
_cell_angle_beta                 100.55(3)
_cell_angle_gamma                99.28(3)
_cell_formula_units_Z            2
_cell_length_a                   7.7439(15)
_cell_length_b                   10.464(2)
_cell_length_c                   10.683(2)
_cell_measurement_reflns_used    7792
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      26.01
_cell_measurement_theta_min      2.49
_cell_volume                     816.5(3)
_computing_cell_refinement       'Bruker SMART'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SAINT'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.997
_diffrn_measurement_device_type  'CCD area detector'
_diffrn_measurement_method       'phi and omega 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  0.0216
_diffrn_reflns_av_sigmaI/netI    0.0209
_diffrn_reflns_limit_h_max       9
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       13
_diffrn_reflns_limit_l_min       -13
_diffrn_reflns_number            10526
_diffrn_reflns_theta_full        26.03
_diffrn_reflns_theta_max         26.03
_diffrn_reflns_theta_min         1.99
_exptl_absorpt_coefficient_mu    3.853
_exptl_absorpt_correction_T_max  0.6992
_exptl_absorpt_correction_T_min  0.2134
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'Bruker SADABS'
_exptl_crystal_colour            yellow
_exptl_crystal_density_diffrn    2.026
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             472
_exptl_crystal_size_max          0.58
_exptl_crystal_size_mid          0.20
_exptl_crystal_size_min          0.10
_refine_diff_density_max         0.675
_refine_diff_density_min         -0.645
_refine_diff_density_rms         0.103
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.104
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     191
_refine_ls_number_reflns         3216
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.104
_refine_ls_R_factor_all          0.0203
_refine_ls_R_factor_gt           0.0194
_refine_ls_shift/su_max          0.005
_refine_ls_shift/su_mean         0.001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0246P)^2^+0.6108P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0490
_refine_ls_wR_factor_ref         0.0495
_reflns_number_gt                3119
_reflns_number_total             3216
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            cg0580152_nme_dipyridyl_urea_9.cif
_cod_data_source_block           N-MeMDPU
_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_values 1715 2011-07-08 13:25:40Z adriana 
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_cod_database_code               4504808