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_4505327
_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                 96.150(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            8
_cell_length_a                   8.0828(11)
_cell_length_b                   12.5828(16)
_cell_length_c                   9.7644(13)
_cell_measurement_temperature    150(2)
_cell_volume                     987.4(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 0.998
_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  0.0291
_diffrn_reflns_av_sigmaI/netI    0.0305
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       16
_diffrn_reflns_limit_k_min       -16
_diffrn_reflns_limit_l_max       12
_diffrn_reflns_limit_l_min       -12
_diffrn_reflns_number            8238
_diffrn_reflns_theta_full        26.00
_diffrn_reflns_theta_max         28.28
_diffrn_reflns_theta_min         2.53
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.150
_exptl_absorpt_correction_T_max  0.9911
_exptl_absorpt_correction_T_min  0.9606
_exptl_absorpt_correction_type   multi-scan
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.723
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             528
_exptl_crystal_size_max          0.27
_exptl_crystal_size_mid          0.15
_exptl_crystal_size_min          0.06
_refine_diff_density_max         0.542
_refine_diff_density_min         -0.248
_refine_diff_density_rms         0.065
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.099
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     195
_refine_ls_number_reflns         2336
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.099
_refine_ls_R_factor_all          0.0717
_refine_ls_R_factor_gt           0.0560
_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^)+(0.0566P)^2^+0.6928P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1234
_refine_ls_wR_factor_ref         0.1301
_reflns_number_gt                1908
_reflns_number_total             2336
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            cg034209asi20031107_055124.cif
_cod_data_source_block           barbituricacidform2
_cod_original_sg_symbol_H-M      P2(1)/c
_cod_database_code               4505327