The observation of a large gauche preference when 2-fluoroethylamine and 2-fluoroethanol become protonated.
Briggs, Caroline R. S.; Allen, Mark J.; O'Hagan, David; Tozer, David J.; Slawin, Alexandra M. Z.; Goeta, Andrés E; Howard, Judith A. K.; Organic & biomolecular chemistry 2 (2004) 732–740; doi:10.1039/b312188g

data_7151593
_publ_section_title
;
 The observation of a large gauche preference when 2-fluoroethylamine
 and 2-fluoroethanol become protonated.
;
_journal_issue                   5
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              732
_journal_page_last               740
_journal_paper_doi               10.1039/b312188g
_journal_volume                  2
_journal_year                    2004
_chemical_formula_moiety         'C19 H23 Cl F N'
_chemical_formula_sum            'C19 H23 Cl F N'
_chemical_formula_weight         319.83
_chemical_melting_point          ?
_space_group_IT_number           19
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   9.21(3)
_cell_length_b                   12.66(4)
_cell_length_c                   14.89(5)
_cell_measurement_reflns_used    163
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      168
_cell_measurement_theta_min      12
_cell_volume                     1736(10)
_computing_cell_refinement       'Bruker SMART'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SHELXTL'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      293(2)
_diffrn_detector_area_resol_mean 0.9
_diffrn_measured_fraction_theta_full 0.994
_diffrn_measured_fraction_theta_max 0.994
_diffrn_measurement_device_type  'CCD area detector'
_diffrn_measurement_method       'phi and omega scans'
_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  0.0917
_diffrn_reflns_av_sigmaI/netI    0.1085
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       14
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       16
_diffrn_reflns_limit_l_min       -13
_diffrn_reflns_number            7243
_diffrn_reflns_theta_full        23.37
_diffrn_reflns_theta_max         23.37
_diffrn_reflns_theta_min         2.11
_diffrn_standards_decay_%        -
_diffrn_standards_interval_count -
_diffrn_standards_interval_time  -
_diffrn_standards_number         -
_exptl_absorpt_coefficient_mu    0.226
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.724736
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   -
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.224
_exptl_crystal_density_meas      ?
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             680
_exptl_crystal_size_max          .15
_exptl_crystal_size_mid          .2
_exptl_crystal_size_min          .2
_refine_diff_density_max         0.158
_refine_diff_density_min         -0.193
_refine_diff_density_rms         0.040
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -0.06(12)
_refine_ls_extinction_coef       0.0096(14)
_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   0.961
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     204
_refine_ls_number_reflns         2475
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      0.961
_refine_ls_R_factor_all          0.1290
_refine_ls_R_factor_gt           0.0475
_refine_ls_shift/su_max          0.006
_refine_ls_shift/su_mean         0.001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0375P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0793
_refine_ls_wR_factor_ref         0.1007
_reflns_number_gt                1386
_reflns_number_total             2475
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            b312188g.txt
_cod_data_source_block           S-10
_cod_depositor_comments
;
The following automatic conversions were performed:
'_symmetry_cell_setting' value 'Orthorhombic' changed to 'orthorhombic'
according to '/home/adriana/struct/CIF-dictionaries/cif_core.dic'
dictionary named 'cif_core.dic' version 2.4.1 from
2010-06-29.

'_exptl_absorpt_correction_type' value 'multiscan' changed to
'multi-scan' according to
'/home/adriana/struct/CIF-dictionaries/cif_core.dic' dictionary named
'cif_core.dic' version 2.4.1 from 2010-06-29.

Automatic conversion script
Id: cif_fix_enum 1555 2011-01-17 13:19:09Z saulius 

The following automatic conversions were performed:

'_chemical_melting_point' value '-' was changed to '?' - the value is
undefined or not given.

Automatic conversion script
Id: cif_fix_values 1569 2011-02-09 13:29:24Z adriana 

The following automatic conversions were performed:

'_exptl_crystal_density_meas' value '-' was changed to '?' - the
value is perceived as not measured.

Automatic conversion script
Id: cif_fix_values 3008 2015-01-20 13:52:24Z robertas 
;
_cod_original_cell_volume        1735(10)
_cod_original_sg_symbol_H-M      P2(1)2(1)2(1)
_cod_database_code               7151593