1-Methylpiperazine oxalate dihydrate
Callear, Samantha K.; Hursthouse, Michael B.; Crystal Structure Report Archive  (2008) 566–; doi:

data_1519953
_publ_section_title
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 1-Methylpiperazine oxalate dihydrate
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_journal_name_full               'Crystal Structure Report Archive'
_journal_page_first              566
_journal_year                    2008
_chemical_formula_sum            'C7 H18 N2 O6'
_chemical_formula_weight         226.23
_chemical_name_systematic
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1-Methylpiperazinium oxalate dihydrate
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_space_group_IT_number           4
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  'P 2yb'
_symmetry_space_group_name_H-M   'P 1 21 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_cell_angle_alpha                90.00
_cell_angle_beta                 104.266(4)
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   8.2165(4)
_cell_length_b                   7.0534(5)
_cell_length_c                   10.0677(7)
_cell_measurement_reflns_used    1618
_cell_measurement_temperature    120(2)
_cell_measurement_theta_max      23.26
_cell_measurement_theta_min      1.00
_cell_volume                     565.47(6)
_computing_cell_refinement
'DENZO (Otwinowski & Minor, 1997) & COLLECT (Hooft, R.W.W., 1998)'
_computing_data_collection       'COLLECT (Hooft, R.W.W., 1998)'
_computing_data_reduction
'DENZO (Otwinowski & Minor, 1997) & COLLECT (Hooft, R.W.W., 1998)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      120(2)
_diffrn_detector_area_resol_mean 9.091
_diffrn_measured_fraction_theta_full 0.823
_diffrn_measured_fraction_theta_max 0.823
_diffrn_measurement_device_type  'Bruker-Nonius 95mm CCD camera on \k-goniostat'
_diffrn_measurement_method       '\f & \w scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'Bruker-Nonius FR591 rotating anode'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0657
_diffrn_reflns_av_sigmaI/netI    0.0537
_diffrn_reflns_limit_h_max       9
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       11
_diffrn_reflns_limit_l_min       -11
_diffrn_reflns_number            7091
_diffrn_reflns_theta_full        23.35
_diffrn_reflns_theta_max         23.35
_diffrn_reflns_theta_min         3.56
_exptl_absorpt_coefficient_mu    0.115
_exptl_absorpt_correction_T_max  0.9966
_exptl_absorpt_correction_T_min  0.9773
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'SADABS V2.10 (Sheldrick, G.M., 2003)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.329
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             244
_exptl_crystal_size_max          0.20
_exptl_crystal_size_mid          0.11
_exptl_crystal_size_min          0.03
_refine_diff_density_max         0.155
_refine_diff_density_min         -0.167
_refine_diff_density_rms         0.038
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   10(10)
_refine_ls_extinction_coef       0.058(12)
_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   1.063
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     155
_refine_ls_number_reflns         738
_refine_ls_number_restraints     7
_refine_ls_restrained_S_all      1.059
_refine_ls_R_factor_all          0.0462
_refine_ls_R_factor_gt           0.0344
_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^)+(0.0495P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0761
_refine_ls_wR_factor_ref         0.0788
_reflns_number_gt                641
_reflns_number_total             738
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            eCrystal-566.cif
_cod_data_source_block           06skc0059p21
_cod_depositor_comments
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Citation :
Callear, Samantha K. and Hursthouse, Michael B. (2008) 
University of Southampton, Crystal Structure Report Archive. 
(doi:10.5258/ecrystals/566)

More at:
http://ecrystals.chem.soton.ac.uk/566/
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_cod_original_sg_symbol_H-M      P21
_cod_database_code               1519953