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_4504311
_publ_section_title
;
 The Structure of Two Anhydrous Polymorphs of Caffeine from Single-Crystal
 Diffraction and Ultrahigh-Field Solid-State13C NMR Spectroscopy
;
_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            'C15 H10 N5 O2'
_chemical_formula_weight         292.28
_chemical_name_systematic
; 
 ? 
;
_space_group_IT_number           167
_symmetry_cell_setting           trigonal
_symmetry_space_group_name_Hall  '-R 3 2"c'
_symmetry_space_group_name_H-M   'R -3 c :H'
_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                 90.00
_cell_angle_gamma                120.00
_cell_formula_units_Z            3
_cell_length_a                   14.831(3)
_cell_length_b                   14.831(3)
_cell_length_c                   6.7648(19)
_cell_measurement_reflns_used    1217
_cell_measurement_temperature    125(2)
_cell_measurement_theta_max      23.46
_cell_measurement_theta_min      2.75
_cell_volume                     1288.6(5)
_computing_cell_refinement       'SAINT (Bruker 2001)'
_computing_data_collection       SMART
_computing_data_reduction        'SAINT (Bruker 2001)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      125(1)
_diffrn_measured_fraction_theta_full 0.995
_diffrn_measured_fraction_theta_max 0.995
_diffrn_measurement_device_type  'Bruker SMART 1000 CCD'
_diffrn_measurement_method       '/w 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  0.0349
_diffrn_reflns_av_sigmaI/netI    0.0990
_diffrn_reflns_limit_h_max       16
_diffrn_reflns_limit_h_min       -16
_diffrn_reflns_limit_k_max       16
_diffrn_reflns_limit_k_min       -16
_diffrn_reflns_limit_l_max       7
_diffrn_reflns_limit_l_min       -7
_diffrn_reflns_number            3020
_diffrn_reflns_theta_full        23.24
_diffrn_reflns_theta_max         23.24
_diffrn_reflns_theta_min         2.75
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.080
_exptl_absorpt_correction_T_max  0.9905
_exptl_absorpt_correction_T_min  0.9765
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   SADABS
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.130
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       needle
_exptl_crystal_F_000             453
_exptl_crystal_size_max          0.30
_exptl_crystal_size_mid          0.12
_exptl_crystal_size_min          0.12
_refine_diff_density_max         0.139
_refine_diff_density_min         -0.124
_refine_diff_density_rms         0.028
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.194
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     124
_refine_ls_number_reflns         208
_refine_ls_number_restraints     77
_refine_ls_restrained_S_all      0.901
_refine_ls_R_factor_all          0.0780
_refine_ls_R_factor_gt           0.0569
_refine_ls_shift/su_max          0.042
_refine_ls_shift/su_mean         0.008
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0000P)^2^+5.4170P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1449
_refine_ls_wR_factor_ref         0.1795
_reflns_number_gt                141
_reflns_number_total             208
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            cg070291osi20070323_031022.cif
_cod_data_source_block           sadf
_cod_original_sg_symbol_H-M      R-3c
_cod_database_code               4504311