Bis(benzimidazolium) axles and crown ether wheels: a versatile templating pair for the formation of [2]rotaxane molecular shuttles
Zhu, Kelong; Vukotic, V. Nicholas; Noujeim, Nadim; Loeb, Stephen J.; Chemical Science 3 (2012) 3265–; doi:10.1039/c2sc20986a

data_1515242
_publ_section_title
;
 Bis(benzimidazolium) axles and crown ether wheels: a versatile templating
 pair for the formation of [2]rotaxane molecular shuttles
;
_journal_issue                   11
_journal_name_full               'Chemical Science'
_journal_page_first              3265
_journal_paper_doi               10.1039/c2sc20986a
_journal_volume                  3
_journal_year                    2012
_chemical_formula_sum            'C100 H114 N4 O10'
_chemical_formula_weight         1531.95
_chemical_name_systematic
;
?
;
_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   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 100.575(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   14.1231(17)
_cell_length_b                   23.130(3)
_cell_length_c                   26.377(3)
_cell_measurement_reflns_used    222
_cell_measurement_temperature    173(2)
_cell_measurement_theta_max      25.00
_cell_measurement_theta_min      1.94
_cell_volume                     8470.2(18)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SHELXTL XPREP'
_computing_molecular_graphics    'Bruker SHELXTL XP'
_computing_publication_material  'Bruker SHELXTL XCIF'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      173(2)
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device_type  'Bruker APEX-I CCD'
_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  0.1301
_diffrn_reflns_av_sigmaI/netI    0.1168
_diffrn_reflns_limit_h_max       15
_diffrn_reflns_limit_h_min       -15
_diffrn_reflns_limit_k_max       25
_diffrn_reflns_limit_k_min       -25
_diffrn_reflns_limit_l_max       29
_diffrn_reflns_limit_l_min       -29
_diffrn_reflns_number            61059
_diffrn_reflns_theta_full        23.26
_diffrn_reflns_theta_max         23.26
_diffrn_reflns_theta_min         1.94
_exptl_absorpt_coefficient_mu    0.077
_exptl_absorpt_correction_T_max  0.9962
_exptl_absorpt_correction_T_min  0.9774
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   sadabs
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.201
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             3288
_exptl_crystal_size_max          0.30
_exptl_crystal_size_mid          0.16
_exptl_crystal_size_min          0.14
_platon_squeeze_details
;
Refinement of F^2^ against ALL reflections. The weighted R-factor wR and
goodness of fit S are based on F^2^, conventional R-factors R are based
on F, with F set to zero for negative F^2^. The threshold expression of
F^2^ > 2sigma(F^2^) is used only for calculating R-factors(gt) etc. and is
not relevant to the choice of reflections for refinement. R-factors based
on F^2^ are statistically about twice as large as those based on F, and R-
factors based on ALL data will be even larger.

Crystals were very weakly diffracting; a cut-off at 0.8 A was applied
in XPEP to improve data set statistics and allow for a solution. This allowed
the location of all axle and wheel atom psoitions. Electron density in the
lattice appeared to be THF molecules (H-bonded to the open benzimidazolium
NH group) but no satisfactory model could be devised. The unit cell was
calculated to contain an estimated 8 molecules of THF which were treated
as a diffuse contribution to the overall scattering without specific atom
positions by SQUEEZE/PLATON. Three ISOR commands were necessary to restrain
C27 (axle), C72 (crown) and C75 (crown) to have approximate isotropic
behaviour. A single AFIX 66 commands was used to restrain one of the outer
rings of a naphthyl unit to be an idealized hexagon with C-C and bonds
equal to 1.39 A.
;
_refine_diff_density_max         0.871
_refine_diff_density_min         -0.557
_refine_diff_density_rms         0.082
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.068
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     925
_refine_ls_number_reflns         12142
_refine_ls_number_restraints     18
_refine_ls_restrained_S_all      1.070
_refine_ls_R_factor_all          0.2292
_refine_ls_R_factor_gt           0.1690
_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^)+(0.1365P)^2^+51.9337P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.3701
_refine_ls_wR_factor_ref         0.4070
_reflns_number_gt                7094
_reflns_number_total             12142
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            c2sc20986a.txt
_cod_data_source_block           kz88
_cod_original_cell_volume        8470.0(18)
_cod_original_sg_symbol_H-M      P2(1)/c
_cod_database_code               1515242