An Experimental and Theoretical Search for Polymorphs of Barbituric Acid: The Challenges of Even Limited Conformational Flexibility
Lewis, Thomas C.; Tocher, Derek A.; Price, Sarah L.; Crystal Growth & Design 4 (2004) 979–; doi:10.1021/cg034209a

data_4505326
_publ_section_title
;
 An Experimental and Theoretical Search for Polymorphs of Barbituric
 Acid:&#x2009; The Challenges of Even Limited Conformational Flexibility
;
_journal_issue                   5
_journal_name_full               'Crystal Growth &amp; Design'
_journal_page_first              979
_journal_paper_doi               10.1021/cg034209a
_journal_volume                  4
_journal_year                    2004
_chemical_formula_sum            'C4 H4 N2 O3'
_chemical_formula_weight         128.09
_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
_cell_angle_alpha                90.00
_cell_angle_beta                 116.368(4)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   6.7305(18)
_cell_length_b                   14.029(4)
_cell_length_c                   6.2309(16)
_cell_measurement_temperature    150(2)
_cell_volume                     527.1(2)
_computing_cell_refinement       'Bruker SAINT'
_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      150(2)
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.955
_diffrn_measurement_device_type  'Bruker SMART APEX diffractometer'
_diffrn_measurement_method       '\w rotation with narrow frames'
_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  0.0225
_diffrn_reflns_av_sigmaI/netI    0.0227
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       -8
_diffrn_reflns_limit_k_max       17
_diffrn_reflns_limit_k_min       -18
_diffrn_reflns_limit_l_max       8
_diffrn_reflns_limit_l_min       -8
_diffrn_reflns_number            4548
_diffrn_reflns_theta_full        26.00
_diffrn_reflns_theta_max         28.28
_diffrn_reflns_theta_min         2.90
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.141
_exptl_absorpt_correction_T_max  0.9958
_exptl_absorpt_correction_T_min  0.9577
_exptl_absorpt_correction_type   multi-scan
_exptl_crystal_colour            Colourless
_exptl_crystal_density_diffrn    1.614
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       Plate
_exptl_crystal_F_000             264
_exptl_crystal_size_max          0.31
_exptl_crystal_size_mid          0.08
_exptl_crystal_size_min          0.03
_refine_diff_density_max         0.316
_refine_diff_density_min         -0.195
_refine_diff_density_rms         0.048
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.097
_refine_ls_hydrogen_treatment    refall
_refine_ls_matrix_type           full
_refine_ls_number_parameters     98
_refine_ls_number_reflns         1246
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.097
_refine_ls_R_factor_all          0.0455
_refine_ls_R_factor_gt           0.0394
_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^)+(0.0511P)^2^+0.1495P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0981
_refine_ls_wR_factor_ref         0.1017
_reflns_number_gt                1105
_reflns_number_total             1246
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            cg034209asi20031107_055124.cif
_cod_data_source_block           barbituricacidform1
_cod_original_sg_symbol_H-M      P2(1)/c
_cod_database_code               4505326