Absolute structure of <i>R</i>-({-})-2-methylpiperazine and <i>S</i>-(+)-2-methylpiperazine
Reibenspies, Joseph; Bhuvanesh, Nattamai; Acta Crystallographica Section B 69 (2013) 288–293; doi:10.1107/S2052519213008713

data_2105467
_publ_section_title
;
 Absolute structure of <i>R</i>-({-})-2-methylpiperazine and
 <i>S</i>-(+)-2-methylpiperazine
;
_journal_coeditor_code           RY5050
_journal_issue                   3
_journal_name_full               'Acta Crystallographica Section B'
_journal_page_first              288
_journal_page_last               293
_journal_paper_doi               10.1107/S2052519213008713
_journal_volume                  69
_journal_year                    2013
_chemical_formula_sum            'C5 H14.71 Br2 N2 O0.36'
_chemical_formula_weight         268.40
_chemical_name_systematic
;
R-(-)-2-methylpiperazinediium dibromide
;
_space_group_crystal_system      monoclinic
_space_group_IT_number           4
_space_group_name_Hall           'P 2yb'
_space_group_name_H-M_alt        'P 1 21 1'
_symmetry_space_group_name_Hall  'P 2yb'
_symmetry_space_group_name_H-M   'P 1 21 1'
_atom_sites_solution_hydrogens   mixed
_audit_creation_method           SHELXL-2012
_cell_angle_alpha                90
_cell_angle_beta                 106.911(2)
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   6.0418(3)
_cell_length_b                   11.5649(5)
_cell_length_c                   7.1333(3)
_cell_measurement_reflns_used    8198
_cell_measurement_temperature    110(2)
_cell_measurement_theta_max      63.87
_cell_measurement_theta_min      7.54
_cell_volume                     476.87(4)
_computing_cell_refinement       'FRAMBO (Bruker, 2002)'
_computing_data_collection       'FRAMBO (Bruker, 2002)'
_computing_data_reduction        'SAINT (Bruker, 2012b)'
_computing_molecular_graphics    'OLEX-2 (Dolomanov, 2009)'
_computing_publication_material  'Ciftab (Sheldrick, 2008)'
_computing_structure_refinement  'SHELXL-2012 (Sheldrick, 2012)'
_computing_structure_solution    'SHELXS (Sheldrick 2008)'
_diffrn_ambient_temperature      110(2)
_diffrn_measured_fraction_theta_full 0.908
_diffrn_measured_fraction_theta_max 0.988
_diffrn_measurement_device_type  'MWPC area detector'
_diffrn_measurement_method       'phi and omega scans'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0335
_diffrn_reflns_limit_h_max       6
_diffrn_reflns_limit_h_min       -6
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       -13
_diffrn_reflns_limit_l_max       8
_diffrn_reflns_limit_l_min       -8
_diffrn_reflns_number            10680
_diffrn_reflns_theta_full        67.679
_diffrn_reflns_theta_max         63.887
_diffrn_reflns_theta_min         6.486
_exptl_absorpt_coefficient_mu    10.281
_exptl_absorpt_correction_T_max  0.4636
_exptl_absorpt_correction_T_min  0.2435
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
SADABS-2009/1 (Bruker,2009) was employed for absorption correction.
wR2(int) was   0.1305 before and   0.0486 after correction.
The ratio of minimum to maximum transmission factors was   0.5252.
Additional spherical absorption correction applied with mu*r =  0.6000.
The \l/2 correction factor of 0.0015 was applied.
;
_exptl_crystal_colour            'colorless '
_exptl_crystal_density_diffrn    1.869
_exptl_crystal_description       'plate     '
_exptl_crystal_F_000             263
_exptl_crystal_size_max          0.210
_exptl_crystal_size_mid          0.110
_exptl_crystal_size_min          0.040
_refine_diff_density_max         0.513
_refine_diff_density_min         -0.644
_refine_ls_abs_structure_details
;
 Flack x determined using 697 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons and Flack (2004), Acta Cryst. A60, s61).
;
_refine_ls_abs_structure_Flack   0.041(13)
_refine_ls_extinction_coef       0.0158(10)
_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   1.029
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     96
_refine_ls_number_reflns         1537
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.028
_refine_ls_R_factor_all          0.0199
_refine_ls_R_factor_gt           0.0196
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
;
 w=1/[\s^2^(Fo^2^)+(0.0500P)^2^+0.0247P]
 where P=(Fo^2^+2Fc^2^)/3
;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0594
_refine_ls_wR_factor_ref         0.0597
_reflns_number_gt                1517
_reflns_number_total             1537
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            ry5050.cif
_cod_data_source_block           rmpipbr
_cod_database_code               2105467
_cod_database_fobs_code          2105467
_shelx_estimated_absorpt_t_min   0.221
_shelx_estimated_absorpt_t_max   0.684
_shelx_hkl_checksum              29333
_shelx_res_checksum              4432
_shelxl_version_number           .002012