New Conformations and Binding Modes in Halogen-Bonded and Ionic Complexes of 2,3,5,6-Tetra(2‘-pyridyl)pyrazine
Padgett, Clifford W.; Walsh, Rosa D.; Drake, Gregory W.; Hanks, Timothy W.; Pennington, William T.; Crystal Growth & Design 5 (2005) 745–; doi:10.1021/cg049730z

data_4504989
_publ_section_title
;
 New Conformations and Binding Modes in Halogen-Bonded and Ionic Complexes
 of 2,3,5,6-Tetra(2&#x2018;-pyridyl)pyrazine
;
_journal_issue                   2
_journal_name_full               'Crystal Growth &amp; Design'
_journal_page_first              745
_journal_paper_doi               10.1021/cg049730z
_journal_volume                  5
_journal_year                    2005
_chemical_formula_moiety         'C24 H16 N6, C2I4'
_chemical_formula_sum            'C26 H16 I4 N6'
_chemical_formula_weight         920.05
_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                 92.41(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   11.607(4)
_cell_length_b                   13.987(6)
_cell_length_c                   17.854(5)
_cell_measurement_reflns_used    49
_cell_measurement_temperature    295(2)
_cell_measurement_theta_max      24.94
_cell_measurement_theta_min      20.05
_cell_volume                     2896.0(18)
_computing_cell_refinement       'Siemens P3 software (1989)'
_computing_data_collection       'Siemens P3 software (1989)'
_computing_data_reduction        'SHELXTL,VERSION 6.10 Sheldick (2000)'
_computing_molecular_graphics    'SHELXTL,VERSION 6.10'
_computing_publication_material  'SHELXTL,VERSION 6.10'
_computing_structure_refinement  'SHELXTL,VERSION 6.10'
_computing_structure_solution    'SHELXTL,VERSION 6.10'
_diffrn_ambient_temperature      295(2)
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device_type  'Nicolet R3mV diffractometer'
_diffrn_measurement_method       \w-2\q
_diffrn_radiation_detector       'Nicolet R3mV serial detector'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'sealed X-ray tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0267
_diffrn_reflns_av_sigmaI/netI    0.0189
_diffrn_reflns_limit_h_max       13
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       0
_diffrn_reflns_limit_k_min       -16
_diffrn_reflns_limit_l_max       21
_diffrn_reflns_limit_l_min       -21
_diffrn_reflns_number            2693
_diffrn_reflns_theta_full        25.03
_diffrn_reflns_theta_max         25.03
_diffrn_reflns_theta_min         2.28
_diffrn_standards_decay_%        0.00
_diffrn_standards_interval_count 97
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    4.330
_exptl_absorpt_correction_T_max  1.00
_exptl_absorpt_correction_T_min  0.79
_exptl_absorpt_correction_type   psi-scan
_exptl_crystal_colour            'light yellow'
_exptl_crystal_density_diffrn    2.110
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       parallelepiped
_exptl_crystal_F_000             1704
_exptl_crystal_size_max          0.31
_exptl_crystal_size_mid          0.27
_exptl_crystal_size_min          0.24
_refine_diff_density_max         0.803
_refine_diff_density_min         -1.041
_refine_diff_density_rms         0.159
_refine_ls_extinction_coef       0.00604(15)
_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   1.075
_refine_ls_hydrogen_treatment    ref
_refine_ls_matrix_type           full
_refine_ls_number_parameters     197
_refine_ls_number_reflns         2559
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.075
_refine_ls_R_factor_all          0.0301
_refine_ls_R_factor_gt           0.0261
_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^)+(0.0407P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0609
_refine_ls_wR_factor_ref         0.0618
_reflns_number_gt                2235
_reflns_number_total             2559
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            cg049730zsi20040802_040315.cif
_cod_data_source_block           fd0763
_cod_original_sg_symbol_H-M      C2/c
_cod_database_code               4504989