Temperature dependent solid-state proton migration in dimethylurea-oxalic acid complexes.
Jones, Andrew O. F.; Lemée-Cailleau, Marie-Hélène; Martins, David M. S.; McIntyre, Garry J.; Oswald, Iain D. H.; Pulham, Colin R.; Spanswick, Christopher K.; Thomas, Lynne H.; Wilson, Chick C.; Physical chemistry chemical physics : PCCP 14 (2012) 13273–13283; doi:10.1039/c2cp41782k

data_7208828
_publ_section_title
;
 Temperature dependent solid-state proton migration in dimethylurea-oxalic
 acid complexes.
;
_journal_issue                   38
_journal_name_full               'Physical chemistry chemical physics : PCCP'
_journal_page_first              13273
_journal_page_last               13283
_journal_paper_doi               10.1039/c2cp41782k
_journal_volume                  14
_journal_year                    2012
_chemical_formula_sum            'C8 H18 N4 O6'
_chemical_formula_weight         266.26
_chemical_name_common
;
bis(N,N-Dimethylurea) oxalic acid
;
_chemical_name_systematic
;
bis(N,N-Dimethylurea) ethanedioic acid
;
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 1'
_atom_sites_solution_hydrogens   difmap
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 111.407(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   7.7944(3)
_cell_length_b                   6.4482(2)
_cell_length_c                   13.6550(6)
_cell_measurement_reflns_used    5667
_cell_measurement_temperature    200
_cell_measurement_theta_max      55.14
_cell_measurement_theta_min      6.32
_cell_volume                     638.95(4)
_computing_cell_refinement       'CrystalClear 1.4.0 (Rigaku, 2008)'
_computing_data_collection       'CrystalClear 1.4.0 (Rigaku, 2008)'
_computing_data_reduction        'CrystalClear 1.4.0 (Rigaku, 2008)'
_computing_molecular_graphics    'Mercury (McRae, 2006)'
_computing_publication_material  'WINGX (Farrugia, 1999)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      200
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.997
_diffrn_measurement_device_type  'Rigaku R-AXIS RAPID IP Image Plate'
_diffrn_measurement_method       'Image plate'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0165
_diffrn_reflns_av_sigmaI/netI    0.0135
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -8
_diffrn_reflns_limit_l_max       17
_diffrn_reflns_limit_l_min       -17
_diffrn_reflns_number            8005
_diffrn_reflns_theta_full        27.48
_diffrn_reflns_theta_max         27.48
_diffrn_reflns_theta_min         3.20
_exptl_absorpt_coefficient_mu    0.118
_exptl_absorpt_correction_T_max  1.0000
_exptl_absorpt_correction_T_min  0.7875
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'ABSCOR, Rigaku 1995'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.384
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             284
_exptl_crystal_size_max          0.4
_exptl_crystal_size_mid          0.2
_exptl_crystal_size_min          0.2
_refine_diff_density_max         0.265
_refine_diff_density_min         -0.216
_refine_diff_density_rms         0.061
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.124
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     94
_refine_ls_number_reflns         1460
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.124
_refine_ls_R_factor_all          0.0577
_refine_ls_R_factor_gt           0.0511
_refine_ls_shift/su_max          0.014
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0856P)^2^+0.1542P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1498
_refine_ls_wR_factor_ref         0.1566
_reflns_number_gt                1183
_reflns_number_total             1460
_reflns_threshold_expression     >2\s(I)
_cod_data_source_file            c2cp41782k.txt
_cod_data_source_block           dmuox_200k
_cod_original_sg_symbol_H-M      P21/c
_cod_database_code               7208828