Unexpected beauty and diversity in the structures of three homologous 4,5-dialkoxy-1-ethynyl-2-nitrobenzenes: the subtle interplay between intermolecular C-H...O hydrogen bonds and alkyl chain length.
Oburn, Shalisa M.; Bosch, Eric; Acta crystallographica. Section C, Structural chemistry 73 (2017) 814–819; doi:10.1107/S2053229617012761

data_2311912
_publ_section_title
;
 Unexpected beauty and diversity in the structures of three homologous
 4,5-dialkoxy-1-ethynyl-2-nitrobenzenes: the subtle interplay between
 intermolecular C-H...O hydrogen bonds and alkyl chain length.
;
_journal_issue                   'Pt 10'
_journal_name_full
'Acta crystallographica. Section C, Structural chemistry'
_journal_page_first              814
_journal_page_last               819
_journal_paper_doi               10.1107/S2053229617012761
_journal_volume                  73
_journal_year                    2017
_chemical_formula_moiety         'C16 H21 N O4'
_chemical_formula_sum            'C16 H21 N O4'
_chemical_formula_weight         291.34
_chemical_name_systematic        1,2-dibutoxy-4-ethynyl-5-nitrobenzene
_space_group_crystal_system      monoclinic
_space_group_IT_number           14
_space_group_name_Hall           '-P 2ybc'
_space_group_name_H-M_alt        'P 1 21/c 1'
_atom_sites_solution_hydrogens   mixed
_audit_creation_method           SHELXL-2017/1
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_cell_angle_beta                 97.9670(10)
_cell_angle_gamma                90
_cell_formula_units_Z            4
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_cell_length_b                   18.0914(10)
_cell_length_c                   9.9579(5)
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_cell_measurement_theta_min      2.25
_cell_volume                     1520.24(14)
_computing_cell_refinement       'Bruker SMART'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'XSeed (Barbour, 2001)'
_computing_publication_material  'XSeed (Barbour, 2001)'
_computing_structure_refinement  'SHELXL-2017/1 (Sheldrick, 2015a)'
_computing_structure_solution    'SHELXT 2014/5 (Sheldrick, 2015)'
_diffrn_ambient_temperature      100(2)
_diffrn_detector_area_resol_mean 8.3660
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device_type  'Bruker APEXII CCD area-detector'
_diffrn_measurement_method       '\f and \w'
_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  0.0470
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_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       23
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_diffrn_reflns_limit_l_min       -12
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_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         27.174
_diffrn_reflns_theta_min         2.251
_exptl_absorpt_coefficient_mu    0.091
_exptl_absorpt_correction_T_max  0.7455
_exptl_absorpt_correction_T_min  0.6823
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   '(SADABS Version 2014; Bruker AXS)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.273
_exptl_crystal_description       'irregular block'
_exptl_crystal_F_000             624
_exptl_crystal_size_max          0.600
_exptl_crystal_size_mid          0.340
_exptl_crystal_size_min          0.024
_refine_diff_density_max         0.254
_refine_diff_density_min         -0.184
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.022
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     198
_refine_ls_number_reflns         3370
_refine_ls_number_restraints     2
_refine_ls_restrained_S_all      1.021
_refine_ls_R_factor_all          0.0665
_refine_ls_R_factor_gt           0.0413
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w = 1/[\s^2^(Fo^2^)+(0.0447P)^2^+0.5063P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0922
_refine_ls_wR_factor_ref         0.1029
_reflns_number_gt                2449
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_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            fn3243sup1.cif
_cod_data_source_block           2
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_cod_database_code               2311912
_shelx_estimated_absorpt_t_min   0.947
_shelx_estimated_absorpt_t_max   0.998
_shelx_hkl_checksum              38593
_shelx_res_checksum              67803