 
data_6a
  
_audit_creation_method            'SHELXL-2017/1' 
_shelx_SHELXL_version_number      '2017/1' 
_chemical_name_systematic         ? 
_chemical_name_common             ? 
_chemical_melting_point           ? 
_chemical_formula_moiety
 'C18 H18 Br2 O4' 
_chemical_formula_sum 
 'C18 H18 Br2 O4' 
_chemical_formula_weight          458.14 
  
loop_ 
 _atom_type_symbol 
 _atom_type_description 
 _atom_type_scat_dispersion_real 
 _atom_type_scat_dispersion_imag 
 _atom_type_scat_source 
 'C'  'C'   0.0033   0.0016 
 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 
 'H'  'H'   0.0000   0.0000 
 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 
 'Br'  'Br'  -0.2901   2.4595 
 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 
 'O'  'O'   0.0106   0.0060 
 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 
  
_space_group_crystal_system       monoclinic 
_space_group_IT_number            14 
_space_group_name_H-M_alt         'P 21/n' 
_space_group_name_Hall            '-P 2yn' 
  
_shelx_space_group_comment 
; 
The symmetry employed for this shelxl refinement is uniquely defined 
by the following loop, which should always be used as a source of 
symmetry information in preference to the above space-group names. 
They are only intended as comments. 
; 
  
loop_ 
 _space_group_symop_operation_xyz 
 'x, y, z' 
 '-x+1/2, y+1/2, -z+1/2' 
 '-x, -y, -z' 
 'x-1/2, -y-1/2, z-1/2' 
  
_cell_length_a                    11.1133(6) 
_cell_length_b                    9.9384(4) 
_cell_length_c                    16.6772(7) 
_cell_angle_alpha                 90 
_cell_angle_beta                  105.467(5) 
_cell_angle_gamma                 90 
_cell_volume                      1775.25(15) 
_cell_formula_units_Z             4 
_cell_measurement_temperature     173(2) 
_cell_measurement_reflns_used     1509 
_cell_measurement_theta_min       2.5430 
_cell_measurement_theta_max       27.1840 
  
_exptl_crystal_description        'platy needles' 
_exptl_crystal_colour             Colourless 
_exptl_crystal_density_meas       ? 
_exptl_crystal_density_method     ? 
_exptl_crystal_density_diffrn     1.714 
_exptl_crystal_F_000              912 
_exptl_transmission_factor_min    ? 
_exptl_transmission_factor_max    ? 
_exptl_crystal_size_max           0.539 
_exptl_crystal_size_mid           0.100 
_exptl_crystal_size_min           0.023 
_exptl_absorpt_coefficient_mu     4.585 
_shelx_estimated_absorpt_T_min    ? 
_shelx_estimated_absorpt_T_max    ? 
_exptl_absorpt_correction_type    analytical 
_exptl_absorpt_correction_T_min   0.450 
_exptl_absorpt_correction_T_max   0.902 
_exptl_absorpt_process_details     
; 
CrysAlisPro 1.171.38.46 (Rigaku Oxford Diffraction, 2015) 
Analytical numeric absorption correction using a multifaceted crystal 
model based on expressions derived by R.C. Clark & J.S. Reid. 
(Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897) 
Empirical absorption correction using spherical harmonics, 
implemented in SCALE3 ABSPACK scaling algorithm. 
; 
_exptl_absorpt_special_details    ? 
_diffrn_ambient_temperature       173(2) 
_diffrn_radiation_wavelength      0.71073 
_diffrn_radiation_type            MoK\a 
_diffrn_source                    'Enhance (Mo) X-ray Source' 
_diffrn_measurement_device_type   'Agilent Xcalibur 3 E' 
_diffrn_measurement_method        'omega scans' 
_diffrn_detector_area_resol_mean  16.0382 
_diffrn_reflns_number             6084 
_diffrn_reflns_av_unetI/netI      0.0594 
_diffrn_reflns_av_R_equivalents   0.0301 
_diffrn_reflns_limit_h_min        -8 
_diffrn_reflns_limit_h_max        14 
_diffrn_reflns_limit_k_min        -12 
_diffrn_reflns_limit_k_max        7 
_diffrn_reflns_limit_l_min        -22 
_diffrn_reflns_limit_l_max        14 
_diffrn_reflns_theta_min          2.534 
_diffrn_reflns_theta_max          28.093 
_diffrn_reflns_theta_full         25.242 
_diffrn_measured_fraction_theta_max   0.821 
_diffrn_measured_fraction_theta_full  0.990 
_diffrn_reflns_Laue_measured_fraction_max    0.821 
_diffrn_reflns_Laue_measured_fraction_full   0.990 
_diffrn_reflns_point_group_measured_fraction_max   0.821 
_diffrn_reflns_point_group_measured_fraction_full  0.990 
_reflns_number_total              3554 
_reflns_number_gt                 2669 
_reflns_threshold_expression      'I > 2σ(I)' 
_reflns_Friedel_coverage          0.000 
_reflns_Friedel_fraction_max      . 
_reflns_Friedel_fraction_full     . 
  
_reflns_special_details 
; 
 Reflections were merged by SHELXL according to the crystal 
 class for the calculation of statistics and refinement. 
  
 _reflns_Friedel_fraction is defined as the number of unique 
 Friedel pairs measured divided by the number that would be 
 possible theoretically, ignoring centric projections and 
 systematic absences. 
; 
  
_computing_data_collection        'CrysAlisPro, Rigaku OD' 
_computing_cell_refinement        'CrysAlisPro, Rigaku OD' 
_computing_data_reduction         'CrysAlisPro, Rigaku OD' 
_computing_structure_solution     'SHELXS-2014 (Sheldrick, 2017)' 
_computing_structure_refinement 'SHELXL-2017/1 (Sheldrick, 2017)' 
_computing_molecular_graphics     'Bruker SHELXTL' 
_computing_publication_material   'CIFTAB-2014 (Sheldrick, 2017)' 
_refine_special_details           ? 
_refine_ls_structure_factor_coef  Fsqd 
_refine_ls_matrix_type            full 
_refine_ls_weighting_scheme       calc 
_refine_ls_weighting_details 
'w=1/[σ²(Fo²)+(0.0289P)²] where P=(Fo²+2Fc²)/3' 
_atom_sites_solution_primary      ? 
_atom_sites_solution_secondary    ? 
_atom_sites_solution_hydrogens    geom 
_refine_ls_hydrogen_treatment     constr 
_refine_ls_extinction_method      none 
_refine_ls_extinction_coef        . 
_refine_ls_number_reflns          3554 
_refine_ls_number_parameters      221 
_refine_ls_number_restraints      0 
_refine_ls_R_factor_all           0.0634 
_refine_ls_R_factor_gt            0.0384 
_refine_ls_wR_factor_ref          0.0815 
_refine_ls_wR_factor_gt           0.0711 
_refine_ls_goodness_of_fit_ref    1.034 
_refine_ls_restrained_S_all       1.034 
_refine_ls_shift/su_max           0.001 
_refine_ls_shift/su_mean          0.000 
  
loop_ 
 _atom_site_label 
 _atom_site_type_symbol 
 _atom_site_fract_x 
 _atom_site_fract_y 
 _atom_site_fract_z 
 _atom_site_U_iso_or_equiv 
 _atom_site_adp_type 
 _atom_site_occupancy 
 _atom_site_site_symmetry_order 
 _atom_site_calc_flag 
 _atom_site_refinement_flags_posn 
 _atom_site_refinement_flags_adp 
 _atom_site_refinement_flags_occupancy 
 _atom_site_disorder_assembly 
 _atom_site_disorder_group 
C1 C 0.5358(3) 0.2992(4) 0.4259(2) 0.0236(8) Uani 1 1 d . . . . . 
C2 C 0.5683(3) 0.2977(4) 0.3498(2) 0.0243(9) Uani 1 1 d . . . . . 
Br2 Br 0.49519(4) 0.17084(4) 0.26533(2) 0.03391(13) Uani 1 1 d . . . . . 
C3 C 0.6657(4) 0.3742(4) 0.3378(2) 0.0257(9) Uani 1 1 d . . . . . 
C4 C 0.7367(3) 0.4530(4) 0.4039(2) 0.0274(9) Uani 1 1 d . . . . . 
C5 C 0.7150(4) 0.4430(4) 0.4813(2) 0.0286(9) Uani 1 1 d . . . . . 
H5A H 0.767199 0.490065 0.527052 0.034 Uiso 1 1 calc R U . . . 
C6 C 0.6173(4) 0.3644(4) 0.4929(2) 0.0247(9) Uani 1 1 d . . . . . 
C7 C 0.6022(4) 0.3369(4) 0.5791(2) 0.0278(9) Uani 1 1 d . . . . . 
H7A H 0.535799 0.395097 0.589826 0.033 Uiso 1 1 calc R U . . . 
H7B H 0.681138 0.356884 0.621642 0.033 Uiso 1 1 calc R U . . . 
C8 C 0.5675(3) 0.1886(4) 0.5841(2) 0.0280(9) Uani 1 1 d . . . . . 
H8A H 0.634297 0.130450 0.574077 0.034 Uiso 1 1 calc R U . . . 
H8B H 0.557840 0.168116 0.640189 0.034 Uiso 1 1 calc R U . . . 
C9 C 0.4462(4) 0.1620(4) 0.5190(2) 0.0236(9) Uani 1 1 d . . . . . 
C10 C 0.3529(4) 0.0840(4) 0.5374(2) 0.0262(9) Uani 1 1 d . . . . . 
H10A H 0.369903 0.035518 0.588321 0.031 Uiso 1 1 calc R U . . . 
C11 C 0.2352(4) 0.0766(4) 0.4819(2) 0.0250(9) Uani 1 1 d . . . . . 
C12 C 0.2092(3) 0.1554(3) 0.4095(2) 0.0225(8) Uani 1 1 d . . . . . 
C13 C 0.3034(3) 0.2303(4) 0.3917(2) 0.0230(9) Uani 1 1 d . . . . . 
Br13 Br 0.25306(4) 0.35309(4) 0.30165(2) 0.02965(13) Uani 1 1 d . . . . . 
C14 C 0.4269(3) 0.2282(4) 0.4426(2) 0.0223(8) Uani 1 1 d . . . . . 
O15 O 0.6922(2) 0.3765(3) 0.26163(15) 0.0301(6) Uani 1 1 d . . . . . 
C16 C 0.8017(4) 0.3017(4) 0.2590(2) 0.0408(11) Uani 1 1 d . . . . . 
H16A H 0.820010 0.316490 0.205372 0.061 Uiso 1 1 calc R U . . . 
H16B H 0.787166 0.205629 0.265858 0.061 Uiso 1 1 calc R U . . . 
H16C H 0.872711 0.331883 0.304060 0.061 Uiso 1 1 calc R U . . . 
O17 O 0.8283(3) 0.5287(3) 0.38523(16) 0.0367(7) Uani 1 1 d . . . . . 
C18 C 0.8829(4) 0.6331(4) 0.4426(3) 0.0476(12) Uani 1 1 d . . . . . 
H18A H 0.935881 0.689930 0.418116 0.071 Uiso 1 1 calc R U . . . 
H18B H 0.933571 0.592893 0.494270 0.071 Uiso 1 1 calc R U . . . 
H18C H 0.816634 0.688056 0.454731 0.071 Uiso 1 1 calc R U . . . 
O19 O 0.1377(2) 0.0033(3) 0.49273(15) 0.0322(7) Uani 1 1 d . . . . . 
C20 C 0.1598(4) -0.0789(4) 0.5656(2) 0.0377(11) Uani 1 1 d . . . . . 
H20A H 0.223533 -0.146442 0.564312 0.056 Uiso 1 1 calc R U . . . 
H20B H 0.082167 -0.124204 0.567289 0.056 Uiso 1 1 calc R U . . . 
H20C H 0.188856 -0.022479 0.615203 0.056 Uiso 1 1 calc R U . . . 
O21 O 0.0879(2) 0.1657(2) 0.36169(14) 0.0242(6) Uani 1 1 d . . . . . 
C22 C 0.0564(4) 0.0648(4) 0.2974(2) 0.0368(10) Uani 1 1 d . . . . . 
H22A H 0.109247 0.076205 0.259301 0.055 Uiso 1 1 calc R U . . . 
H22B H -0.031466 0.074270 0.266541 0.055 Uiso 1 1 calc R U . . . 
H22C H 0.070215 -0.024865 0.322736 0.055 Uiso 1 1 calc R U . . . 
  
  
_geom_special_details 
; 
 All esds (except the esd in the dihedral angle between two l.s. planes) 
 are estimated using the full covariance matrix.  The cell esds are taken 
 into account individually in the estimation of esds in distances, angles 
 and torsion angles; correlations between esds in cell parameters are only 
 used when they are defined by crystal symmetry.  An approximate (isotropic) 
 treatment of cell esds is used for estimating esds involving l.s. planes. 
; 
  
loop_ 
 _geom_bond_atom_site_label_1 
 _geom_bond_atom_site_label_2 
 _geom_bond_distance 
 _geom_bond_site_symmetry_2 
 _geom_bond_publ_flag 
C1 C6 1.396(5) . ? 
C1 C2 1.409(5) . ? 
C1 C14 1.490(5) . ? 
C2 C3 1.380(5) . ? 
C2 Br2 1.904(4) . ? 
C3 O15 1.379(4) . ? 
C3 C4 1.409(5) . ? 
C4 O17 1.367(4) . ? 
C4 C5 1.377(5) . ? 
C5 C6 1.393(5) . ? 
C6 C7 1.516(5) . ? 
C7 C8 1.532(5) . ? 
C8 C9 1.512(5) . ? 
C9 C10 1.392(5) . ? 
C9 C14 1.399(5) . ? 
C10 C11 1.388(5) . ? 
C11 O19 1.357(4) . ? 
C11 C12 1.403(5) . ? 
C12 O21 1.375(4) . ? 
C12 C13 1.380(5) . ? 
C13 C14 1.408(5) . ? 
C13 Br13 1.900(3) . ? 
O15 C16 1.437(4) . ? 
O17 C18 1.432(5) . ? 
O19 C20 1.430(4) . ? 
O21 C22 1.442(4) . ? 
  
loop_ 
 _geom_angle_atom_site_label_1 
 _geom_angle_atom_site_label_2 
 _geom_angle_atom_site_label_3 
 _geom_angle 
 _geom_angle_site_symmetry_1 
 _geom_angle_site_symmetry_3 
 _geom_angle_publ_flag 
C6 C1 C2 117.3(3) . . ? 
C6 C1 C14 117.1(3) . . ? 
C2 C1 C14 125.4(3) . . ? 
C3 C2 C1 121.6(3) . . ? 
C3 C2 Br2 117.0(3) . . ? 
C1 C2 Br2 120.8(3) . . ? 
O15 C3 C2 120.7(3) . . ? 
O15 C3 C4 119.9(3) . . ? 
C2 C3 C4 119.3(3) . . ? 
O17 C4 C5 125.5(4) . . ? 
O17 C4 C3 115.0(3) . . ? 
C5 C4 C3 119.4(3) . . ? 
C4 C5 C6 120.6(4) . . ? 
C5 C6 C1 120.8(3) . . ? 
C5 C6 C7 121.4(3) . . ? 
C1 C6 C7 117.6(3) . . ? 
C6 C7 C8 108.6(3) . . ? 
C9 C8 C7 108.6(3) . . ? 
C10 C9 C14 121.4(3) . . ? 
C10 C9 C8 120.9(3) . . ? 
C14 C9 C8 117.5(3) . . ? 
C11 C10 C9 120.4(3) . . ? 
O19 C11 C10 125.7(3) . . ? 
O19 C11 C12 115.2(3) . . ? 
C10 C11 C12 119.1(3) . . ? 
O21 C12 C13 121.2(3) . . ? 
O21 C12 C11 119.1(3) . . ? 
C13 C12 C11 119.4(3) . . ? 
C12 C13 C14 122.4(3) . . ? 
C12 C13 Br13 115.8(3) . . ? 
C14 C13 Br13 121.3(3) . . ? 
C9 C14 C13 116.3(3) . . ? 
C9 C14 C1 117.3(3) . . ? 
C13 C14 C1 126.2(3) . . ? 
C3 O15 C16 114.2(3) . . ? 
C4 O17 C18 117.1(3) . . ? 
C11 O19 C20 117.2(3) . . ? 
C12 O21 C22 112.6(3) . . ? 
  
_refine_diff_density_max    0.590 
_refine_diff_density_min   -0.587 
_refine_diff_density_rms    0.102 
  
  
  
#===END

