Structures of N-acetyl-DL-isoleucine, N-acetyl-DL-alloisoleucine and their ammonium salts; role of ammonium ions in crystal structure formation.
Yajima, Tatsuo; Kimura, Makiko; Hori, Yoshihiro; Shiraiwa, Tadashi; Acta crystallographica Section B, Structural science, crystal engineering and materials 72 (2016) 650–657; doi:10.1107/S2052520616007319

data_2311693
_publ_section_title
;
 Structures of N-acetyl-DL-isoleucine, N-acetyl-DL-alloisoleucine and
 their ammonium salts; role of ammonium ions in crystal structure
 formation.
;
_journal_issue                   'Pt 4'
_journal_name_full
'Acta crystallographica Section B, Structural science, crystal engineering and materials'
_journal_page_first              650
_journal_page_last               657
_journal_paper_doi               10.1107/S2052520616007319
_journal_volume                  72
_journal_year                    2016
_chemical_formula_moiety         'C8 H18 N2 O3'
_chemical_formula_sum            'C8 H18 N2 O3'
_chemical_formula_weight         190.24
_chemical_melting_point_gt       171
_chemical_melting_point_lt       173
_space_group_IT_number           33
_space_group_name_Hall           'P 2c -2n'
_space_group_name_H-M_alt        'P n a 21'
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'P 2c -2n'
_symmetry_space_group_name_H-M   'P n a 21'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_cell_angle_alpha                90.0000
_cell_angle_beta                 90.0000
_cell_angle_gamma                90.0000
_cell_formula_units_Z            4
_cell_length_a                   24.376(3)
_cell_length_b                   7.5507(8)
_cell_length_c                   5.8064(5)
_cell_measurement_reflns_used    6092
_cell_measurement_temperature    296
_cell_measurement_theta_max      27.50
_cell_measurement_theta_min      3.17
_cell_volume                     1068.7(2)
_computing_cell_refinement       'RAPID AUTO'
_computing_data_collection       'RAPID AUTO (Rigaku, 2006)'
_computing_data_reduction        'RAPID AUTO'
_computing_molecular_graphics    'CrystalStructure 4.0'
_computing_publication_material  'CrystalStructure 4.0 (Rigaku, 2010)'
_computing_structure_refinement  'SHELXL97 (Sheldrick, 2008)'
_computing_structure_solution    'SIR2004 (Burla, et al., 2005)'
_diffrn_ambient_temperature      296
_diffrn_detector_area_resol_mean 10.000
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_measurement_device_type  'Rigaku R-AXIS RAPID'
_diffrn_measurement_method       \w
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.1065
_diffrn_reflns_limit_h_max       30
_diffrn_reflns_limit_h_min       -31
_diffrn_reflns_limit_k_max       9
_diffrn_reflns_limit_k_min       -9
_diffrn_reflns_limit_l_max       6
_diffrn_reflns_limit_l_min       -7
_diffrn_reflns_number            10031
_diffrn_reflns_theta_full        27.47
_diffrn_reflns_theta_max         27.47
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.090
_exptl_absorpt_correction_T_max  0.998
_exptl_absorpt_correction_T_min  0.441
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'ABSCOR (Rigaku, 1995)'
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.182
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       needle
_exptl_crystal_F_000             416.00
_exptl_crystal_size_max          0.450
_exptl_crystal_size_mid          0.020
_exptl_crystal_size_min          0.020
_refine_diff_density_max         0.210
_refine_diff_density_min         -0.380
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.022
_refine_ls_hydrogen_treatment    refxyz
_refine_ls_number_parameters     190
_refine_ls_number_reflns         2299
_refine_ls_number_restraints     1
_refine_ls_R_factor_gt           0.0551
_refine_ls_shift/su_max          0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w = 1/[\s^2^(Fo^2^)+(0.0690P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_ref         0.1500
_reflns_number_gt                1340
_reflns_number_total             2299
_reflns_threshold_expression     F^2^>2.0\s(F^2^)
_cod_data_source_file            lo5008sup1.cif
_cod_data_source_block           Ac-DL-aIleNH3
_cod_original_cell_volume        1068.70(18)
_cod_database_code               2311693