Polymorphism of the antiviral agent clevudine
Noonan, T. J.; Mzondo, B.; Bourne, S. A.; Caira, M. R.; CrystEngComm 18 (2016) 8172–; doi:10.1039/C6CE01975G

data_7226663
_publ_section_title
;
 Polymorphism of the antiviral agent clevudine
;
_journal_issue                   42
_journal_name_full               CrystEngComm
_journal_page_first              8172
_journal_paper_doi               10.1039/C6CE01975G
_journal_volume                  18
_journal_year                    2016
_chemical_absolute_configuration syn
_chemical_formula_moiety         'C10 H13 F N2 O5'
_chemical_formula_sum            'C10 H13 F N2 O5'
_chemical_formula_weight         260.22
_chemical_melting_point          'Unable to measure as phase transition occurs'
_chemical_name_common            'Clevudine (Form 2)'
_chemical_name_systematic
1-(2-Deoxy-2-fluoro-\&s-L-arabinofuranosyl)-5-methyl-2,4-(1H,3H)-pyrimidinedione
_space_group_crystal_system      monoclinic
_space_group_IT_number           4
_space_group_name_Hall           'P 2yb'
_space_group_name_H-M_alt        'P 1 21 1'
_symmetry_space_group_name_Hall  'P 2yb'
_symmetry_space_group_name_H-M   'P 1 21 1'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2014/7
_audit_update_record
;
2016-08-31 deposited with the CCDC.
2016-09-27 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 105.980(2)
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   8.9716(9)
_cell_length_b                   5.3099(5)
_cell_length_c                   11.8624(11)
_cell_measurement_reflns_used    9445
_cell_measurement_temperature    173(2)
_cell_measurement_theta_max      28.33
_cell_measurement_theta_min      2.361
_cell_volume                     543.27(9)
_computing_cell_refinement       'SAINT, V.7.60a, Bruker AXS Inc, 2006'
_computing_data_collection       'SAINT, V.7.60a, Bruker AXS Inc, 2006'
_computing_data_reduction        'SAINT, V.7.60a, Bruker AXS Inc, 2006'
_computing_molecular_graphics    'POV-Ray for Windows, 2003'
_computing_publication_material  'PLATON (A.L. Spek, 2009)'
_computing_structure_refinement  'SHELXL-2014/7 (Sheldrick, 2014)'
_computing_structure_solution    'SHELXS (Sheldrick, 1997)'
_diffrn_ambient_temperature      173(2)
_diffrn_detector_area_resol_mean n/a
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.997
_diffrn_measurement_device_type  'Bruker Apex Duo diffractometer'
_diffrn_measurement_method       'phi- and omega-scans of 0.50 deg.'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0223
_diffrn_reflns_av_unetI/netI     0.0153
_diffrn_reflns_Laue_measured_fraction_full 0.999
_diffrn_reflns_Laue_measured_fraction_max 0.997
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       15
_diffrn_reflns_limit_l_min       -15
_diffrn_reflns_number            11600
_diffrn_reflns_point_group_measured_fraction_full 0.999
_diffrn_reflns_point_group_measured_fraction_max 0.996
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         28.373
_diffrn_reflns_theta_min         2.361
_diffrn_source                   'fine-focus sealed tube'
_exptl_absorpt_coefficient_mu    0.139
_exptl_absorpt_correction_T_max  0.936
_exptl_absorpt_correction_T_min  0.894
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'SADABS (Sheldrick, 2006)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.591
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             272
_exptl_crystal_recrystallization_method
'Form 2 initially crystallized in an attempted co-crystallization of clevudine and cinnamamide in ethyl acetate. Form 2 powder can be generated quantitatively by liquid-assisted grinding of Form 1 for 2 h with acetonitrile.'
_exptl_crystal_size_max          0.550
_exptl_crystal_size_mid          0.510
_exptl_crystal_size_min          0.480
_refine_diff_density_max         0.295
_refine_diff_density_min         -0.290
_refine_diff_density_rms         0.076
_refine_ls_abs_structure_details
;
 Flack x determined using 1192 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   0.3(2)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.053
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     166
_refine_ls_number_reflns         2705
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.053
_refine_ls_R_factor_all          0.0295
_refine_ls_R_factor_gt           0.0293
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0542P)^2^+0.0843P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0767
_refine_ls_wR_factor_ref         0.0769
_reflns_Friedel_coverage         0.808
_reflns_Friedel_fraction_full    0.999
_reflns_Friedel_fraction_max     0.994
_reflns_number_gt                2677
_reflns_number_total             2705
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c6ce01975g2.cif
_cod_data_source_block           clevudine2
_cod_depositor_comments
'Adding full bibliography for 7226662--7226664.cif.'
_cod_database_code               7226663
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_min   0.928
_shelx_estimated_absorpt_t_max   0.936
_shelx_res_checksum              6723