The Structure of Two Anhydrous Polymorphs of Caffeine from Single-Crystal Diffraction and Ultrahigh-Field Solid-State13C NMR Spectroscopy
Enright, Gary D.; Terskikh, Victor V.; Brouwer, Darren H.; Ripmeester, John A.; Crystal Growth & Design 7 (2007) 1406–; doi:10.1021/cg070291o

data_4504310
_publ_section_title
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 The Structure of Two Anhydrous Polymorphs of Caffeine from Single-Crystal
 Diffraction and Ultrahigh-Field Solid-State13C NMR Spectroscopy
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_journal_issue                   8
_journal_name_full               'Crystal Growth &amp; Design'
_journal_page_first              1406
_journal_paper_doi               10.1021/cg070291o
_journal_volume                  7
_journal_year                    2007
_chemical_formula_sum            'C8 H10 N4 O2'
_chemical_formula_weight         194.20
_space_group_IT_number           15
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-C 2yc'
_symmetry_space_group_name_H-M   'C 1 2/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                 97.825(4)
_cell_angle_gamma                90.00
_cell_formula_units_Z            20
_cell_length_a                   42.521(9)
_cell_length_b                   14.948(3)
_cell_length_c                   6.7923(14)
_cell_measurement_reflns_used    1012
_cell_measurement_temperature    100(1)
_cell_measurement_theta_max      22.27
_cell_measurement_theta_min      2.23
_cell_volume                     4277.0(15)
_computing_cell_refinement       'SAINT (Bruker 2001)'
_computing_data_collection       APEX2
_computing_data_reduction        'SAINT (Bruker 2001)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      100(1)
_diffrn_measured_fraction_theta_full 0.983
_diffrn_measured_fraction_theta_max 0.983
_diffrn_measurement_device_type  'Bruker Kappa APEX II CCD'
_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  0.1021
_diffrn_reflns_av_sigmaI/netI    0.0903
_diffrn_reflns_limit_h_max       44
_diffrn_reflns_limit_h_min       -47
_diffrn_reflns_limit_k_max       16
_diffrn_reflns_limit_k_min       -16
_diffrn_reflns_limit_l_max       7
_diffrn_reflns_limit_l_min       -5
_diffrn_reflns_number            13892
_diffrn_reflns_theta_full        23.28
_diffrn_reflns_theta_max         23.28
_diffrn_reflns_theta_min         3.30
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.113
_exptl_absorpt_correction_T_max  0.9921
_exptl_absorpt_correction_T_min  0.9594
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   SADABS
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.508
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       needle
_exptl_crystal_F_000             2040
_exptl_crystal_size_max          0.37
_exptl_crystal_size_mid          0.07
_exptl_crystal_size_min          0.07
_refine_diff_density_max         0.217
_refine_diff_density_min         -0.223
_refine_diff_density_rms         0.052
_refine_ls_extinction_coef       0.00015(9)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   1.000
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     507
_refine_ls_number_reflns         3046
_refine_ls_number_restraints     518
_refine_ls_restrained_S_all      0.969
_refine_ls_R_factor_all          0.1355
_refine_ls_R_factor_gt           0.0584
_refine_ls_shift/su_max          0.013
_refine_ls_shift/su_mean         0.001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0665P)^2^+5.4630P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1234
_refine_ls_wR_factor_ref         0.1598
_reflns_number_gt                1635
_reflns_number_total             3046
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            cg070291osi20070323_030715.cif
_cod_data_source_block           gary
_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 
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_cod_original_sg_symbol_H-M      C2/c
_cod_database_code               4504310