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_7208831
_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         266.00
_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                 111.940(10)
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   7.840(5)
_cell_length_b                   6.460(5)
_cell_length_c                   13.770(5)
_cell_measurement_reflns_used    250
_cell_measurement_temperature    250
_cell_volume                     646.9(7)
_computing_cell_refinement       'lauegen (CCP4)'
_computing_data_collection       'VIVALDI (MAATEL)'
_computing_data_reduction        'argonne_boxes, laue4 (Piltz, 2011)'
_computing_molecular_graphics    'Mercury (McRae, 2006)'
_computing_publication_material  'WINGX (Farrugia, 1999)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      250
_diffrn_detector_area_resol_mean 0.7
_diffrn_measurement_device_type  VIVALDI
_diffrn_measurement_method       'Laue patterns at 10 orientations'
_diffrn_radiation_monochromator  none
_diffrn_radiation_probe          neutron
_diffrn_radiation_source         'ILL reactor source, thermal guide'
_diffrn_radiation_type           neutron
_diffrn_radiation_wavelength     0.80-5.20
_diffrn_reflns_av_R_equivalents  0.1400
_diffrn_reflns_av_sigmaI/netI    0.0744
_diffrn_reflns_limit_h_max       9
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -8
_diffrn_reflns_limit_l_max       15
_diffrn_reflns_limit_l_min       -15
_diffrn_reflns_number            4852
_diffrn_standards_number         none
_exptl_absorpt_coefficient_mu    0.000
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.366
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             12
_exptl_crystal_size_max          2.5
_exptl_crystal_size_mid          2.2
_exptl_crystal_size_min          1.2
_refine_diff_density_max         0.049
_refine_diff_density_min         -0.060
_refine_diff_density_rms         0.010
_refine_ls_extinction_coef       3.5(7)
_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   1.719
_refine_ls_hydrogen_treatment    refall
_refine_ls_matrix_type           full
_refine_ls_number_parameters     164
_refine_ls_number_reflns         965
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.719
_refine_ls_R_factor_all          0.1024
_refine_ls_R_factor_gt           0.0584
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0300P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1036
_refine_ls_wR_factor_ref         0.1127
_reflns_number_gt                664
_reflns_number_total             965
_reflns_threshold_expression     >2\s(I)
_cod_data_source_file            c2cp41782k.txt
_cod_data_source_block           dmuox_250
_cod_original_sg_symbol_H-M      P21/c
_cod_database_code               7208831