When is a polymorph not a polymorph? Helical trimeric O–H···O synthons in trans-1,4-diethynylcyclohexane-1,4-diol
Bilton, Clair; Howard, Judith A. K.; Laxmi Madhavi, N. N.; Nangia, Ashwini; Desiraju, Gautam R.; Allen, Frank H.; Wilson, Chick C.; Chemical Communications  (1999) 1675–; doi:10.1039/a905025f

data_7110635
_publ_section_title
;
 When is a polymorph not a polymorph? Helical trimeric
 O--H&#x00B7;&#x00B7;&#x00B7;O synthons in
 trans-1,4-diethynylcyclohexane-1,4-diol
;
_journal_issue                   17
_journal_name_full               'Chemical Communications'
_journal_page_first              1675
_journal_paper_doi               10.1039/a905025f
_journal_year                    1999
_chemical_formula_moiety         'C10 H14 O3'
_chemical_formula_sum            'C10 H14 O3'
_chemical_formula_weight         182.00
_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   difmap
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 104.12(3)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   9.925(2)
_cell_length_b                   6.1343(12)
_cell_length_c                   16.725(3)
_cell_measurement_reflns_used    25
_cell_measurement_temperature    150
_cell_volume                     987.5(4)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      150
_diffrn_measurement_device_type  SXD
_diffrn_measurement_method       'Time of flight LAUE diffraction'
_diffrn_radiation_monochromator  none
_diffrn_radiation_probe          neutron
_diffrn_radiation_source         'ISIS spallation source'
_diffrn_radiation_type           neutron
_diffrn_radiation_wavelength     0.5-5.0
_diffrn_reflns_av_R_equivalents  0.0538
_diffrn_reflns_av_sigmaI/netI    0.0732
_diffrn_reflns_limit_h_max       22
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       19
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       33
_diffrn_reflns_limit_l_min       -34
_diffrn_reflns_number            9863
_diffrn_reflns_theta_max         23.54
_diffrn_reflns_theta_min         1.74
_exptl_absorpt_coefficient_mu    0.226
_exptl_absorpt_correction_T_max  0.86
_exptl_absorpt_correction_T_min  0.62
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details
;
The linear absorption coefficient is wavelength dependent and it is
calculated as:
mu = 1.17 + 1.09 * lambda [cm^-1]
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.224
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             126
_exptl_crystal_size_max          2
_exptl_crystal_size_mid          2
_exptl_crystal_size_min          1.5
_refine_diff_density_max         2.242
_refine_diff_density_min         -1.708
_refine_diff_density_rms         0.341
_refine_ls_extinction_coef       0.23
_refine_ls_extinction_method     'Becker-Coppens Lorentzian model'
_refine_ls_goodness_of_fit_ref   3.792
_refine_ls_hydrogen_treatment    refall
_refine_ls_matrix_type           full
_refine_ls_number_parameters     244
_refine_ls_number_reflns         2661
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      3.792
_refine_ls_R_factor_all          0.0889
_refine_ls_R_factor_gt           0.0888
_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^)+(0.0000P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      sigma
_refine_ls_wR_factor_gt          0.1270
_refine_ls_wR_factor_ref         0.1270
_reflns_number_gt                2659
_reflns_number_total             2661
_reflns_threshold_expression     2sigma(I)
_cod_data_source_file            905025fsup1.cif
_cod_data_source_block           3
_cod_original_cell_volume        987.5(3)
_cod_original_sg_symbol_H-M      P2(1)/c
_cod_database_code               7110635