Understanding the NMR chemical shifts for 6-halopurines: role of structure, solvent and relativistic effects.
Standara, Stanislav; Malináková, Katerina; Marek, Radek; Marek, Jaromír; Hocek, Michal; Vaara, Juha; Straka, Michal; Physical chemistry chemical physics : PCCP 12 (2010) 5126–5139; doi:10.1039/b921383j

data_7212175
_publ_section_title
;
 Understanding the NMR chemical shifts for 6-halopurines: role of
 structure, solvent and relativistic effects.
;
_journal_issue                   19
_journal_name_full               'Physical chemistry chemical physics : PCCP'
_journal_page_first              5126
_journal_page_last               5139
_journal_paper_doi               10.1039/b921383j
_journal_volume                  12
_journal_year                    2010
_chemical_formula_moiety         'C12 H9 Cl N4'
_chemical_formula_sum            'C12 H9 Cl N4'
_chemical_formula_weight         244.68
_chemical_name_common            9-benzyl-6-chloropurine
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2yn'
_symmetry_space_group_name_H-M   'P 1 21/n 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                 93.236(8)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   4.9073(4)
_cell_length_b                   24.240(2)
_cell_length_c                   9.3569(8)
_cell_measurement_reflns_used    5007
_cell_measurement_temperature    120(2)
_cell_measurement_theta_max      28.7555
_cell_measurement_theta_min      3.3125
_cell_volume                     1111.26(16)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      120(2)
_diffrn_detector_area_resol_mean 8.3611
_diffrn_measured_fraction_theta_full 0.985
_diffrn_measured_fraction_theta_max 0.985
_diffrn_measurement_device_type  'KUMA KM4 + CCD'
_diffrn_measurement_method       'rotation method, \w--scan'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'Enhance (Mo) X-ray Source'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71069
_diffrn_reflns_av_R_equivalents  0.0779
_diffrn_reflns_av_sigmaI/netI    0.0509
_diffrn_reflns_limit_h_max       5
_diffrn_reflns_limit_h_min       -5
_diffrn_reflns_limit_k_max       28
_diffrn_reflns_limit_k_min       -28
_diffrn_reflns_limit_l_max       9
_diffrn_reflns_limit_l_min       -11
_diffrn_reflns_number            4868
_diffrn_reflns_theta_full        25.00
_diffrn_reflns_theta_max         25.00
_diffrn_reflns_theta_min         2.75
_exptl_absorpt_coefficient_mu    0.324
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.463
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             504
_exptl_crystal_size_max          0.50
_exptl_crystal_size_mid          0.40
_exptl_crystal_size_min          0.25
_refine_diff_density_max         0.390
_refine_diff_density_min         -0.378
_refine_diff_density_rms         0.081
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.071
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     154
_refine_ls_number_reflns         1927
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.071
_refine_ls_R_factor_all          0.0693
_refine_ls_R_factor_gt           0.0665
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0350P)^2^+4.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1562
_refine_ls_wR_factor_ref         0.1574
_reflns_number_gt                1830
_reflns_number_total             1927
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            b921383j.txt
_cod_data_source_block           rm3
_cod_original_sg_symbol_H-M      'P 21/n '
_cod_database_code               7212175