Parallel sheet structure in cyclopropane γ-peptides stabilized by C–H...O hydrogen bonds
M. Khurram N. Qureshi; Martin D. Smith; Chemical Communications  (2006) –; doi:10.1039/b611882h

data_7101595
_publ_section_title
;
Parallel sheet structure in cyclopropane \g-peptides stabilized by
C--H...O hydrogen bonds
;
_journal_issue                   48
_journal_name_full               'Chemical Communications'
_journal_paper_doi               10.1039/b611882h
_journal_year                    2006
_chemical_absolute_configuration
;
1568 Friedel pairs were averaged for the refinement. The absolute
structure was assigned from the KNOWN configuration of the starting
material.
;
_chemical_formula_moiety         'C18 H27 N5 O4'
_chemical_formula_sum            'C18 H27 N5 O4'
_chemical_formula_weight         377.45
_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
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 93.793(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   4.80230(10)
_cell_length_b                   8.6693(2)
_cell_length_c                   24.1050(5)
_cell_measurement_reflns_used    10973
_cell_measurement_temperature    220(2)
_cell_measurement_theta_max      26.37
_cell_measurement_theta_min      1.02
_cell_volume                     1001.36(4)
_computing_cell_refinement       'HKL Scalepack (Otwinowski & Minor 1997)'
_computing_data_collection       'Collect (Nonius B.V. 1998)'
_computing_data_reduction
;
HKL Denzo and Scalepack (Otwinowski & Minor 1997)
;
_computing_publication_material  'SHELXL-97 (Sheldrick 1997)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick 1997)'
_computing_structure_solution    'SIR-92 (Altomare et al. 1994)'
_diffrn_ambient_temperature      220(2)
_diffrn_measured_fraction_theta_full 0.981
_diffrn_measured_fraction_theta_max 0.981
_diffrn_measurement_device_type  'Nonius Kappa CCD'
_diffrn_measurement_method       'Thin slice \w and \f scans'
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0326
_diffrn_reflns_av_sigmaI/netI    0.0273
_diffrn_reflns_limit_h_max       5
_diffrn_reflns_limit_h_min       -5
_diffrn_reflns_limit_k_max       10
_diffrn_reflns_limit_k_min       -9
_diffrn_reflns_limit_l_max       30
_diffrn_reflns_limit_l_min       -29
_diffrn_reflns_number            8057
_diffrn_reflns_theta_full        26.40
_diffrn_reflns_theta_max         26.40
_diffrn_reflns_theta_min         4.12
_exptl_absorpt_coefficient_mu    0.090
_exptl_absorpt_correction_T_max  0.996
_exptl_absorpt_correction_T_min  0.893
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
multi-scan from symmetry-related measurements
Sortav (Blessing 1995)
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.252
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             404
_exptl_crystal_size_max          0.35
_exptl_crystal_size_mid          0.23
_exptl_crystal_size_min          0.05
_refine_diff_density_max         0.383
_refine_diff_density_min         -0.221
_refine_diff_density_rms         0.034
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -1.2(17)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.045
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     228
_refine_ls_number_reflns         2142
_refine_ls_number_restraints     4
_refine_ls_restrained_S_all      1.067
_refine_ls_R_factor_all          0.0481
_refine_ls_R_factor_gt           0.0447
_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^)+(0.0485P)^2^+0.3719P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1073
_refine_ls_wR_factor_ref         0.1106
_reflns_number_gt                2022
_reflns_number_total             2142
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            b611882h.txt
_cod_original_sg_symbol_H-M      P2(1)
_cod_database_code               7101595