(–)-Parasantonic acid and its enol lactone, (+)-parasantonide: observation of the rare acid-to-acid catemeric hydrogen-bonding mode in a γ,ε-diketocarboxylic acid
Zinczuk, Juan; Ruveda, Edmundo A.; Thompson, Hugh W.; Lalancette, Roger A.; Acta Crystallographica Section C 60 (2004) o408–o410; doi:10.1107/S010827010400839X

data_2013986
_publ_section_title
;
 (--)-Parasantonic acid and its enol lactone, (+)-parasantonide:
 observation of the rare acid-to-acid catemeric hydrogen-bonding mode
 in a \g,\e-diketocarboxylic acid
;
_journal_issue                   6
_journal_name_full               'Acta Crystallographica Section C'
_journal_page_first              o408
_journal_page_last               o410
_journal_paper_doi               10.1107/S010827010400839X
_journal_volume                  60
_journal_year                    2004
_chemical_formula_iupac          'C15 H20 O4'
_chemical_formula_moiety         'C15 H20 O4'
_chemical_formula_sum            'C15 H20 O4'
_chemical_formula_weight         264.31
_chemical_melting_point          448
_chemical_name_common            '(+)-parasantonic acid'
_chemical_name_systematic
;
(-)-\a,3a,7-trimethyl-5,8-dioxo-1,4-ethanoperhydropentalene-1-acetic acid
;
_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                   6.770(2)
_cell_length_b                   13.160(3)
_cell_length_c                   15.553(4)
_cell_measurement_reflns_used    30
_cell_measurement_temperature    296(2)
_cell_measurement_theta_max      10.0
_cell_measurement_theta_min      2.6
_cell_volume                     1385.7(6)
_computing_cell_refinement       XSCANS
_computing_data_collection       'XSCANS (Siemens, 1996)'
_computing_data_reduction        XSCANS
_computing_molecular_graphics    'SHELXP97 (Sheldrick, 1997)'
_computing_publication_material  SHELXL97
_computing_structure_refinement  'SHELXL97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 0.990
_diffrn_measured_fraction_theta_max 0.990
_diffrn_measurement_device_type  'Siemens P4'
_diffrn_measurement_method       '2\q/\q 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  0.048
_diffrn_reflns_av_sigmaI/netI    0.058
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       -8
_diffrn_reflns_limit_k_max       15
_diffrn_reflns_limit_k_min       -15
_diffrn_reflns_limit_l_max       18
_diffrn_reflns_limit_l_min       -18
_diffrn_reflns_number            2846
_diffrn_reflns_theta_full        25.05
_diffrn_reflns_theta_max         25.05
_diffrn_reflns_theta_min         2.03
_diffrn_standards_decay_%        'variation < 3.5'
_diffrn_standards_interval_count 97
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    0.091
_exptl_absorpt_correction_T_max  0.990
_exptl_absorpt_correction_T_min  0.976
_exptl_absorpt_correction_type   numerical
_exptl_absorpt_process_details   '(SHELXTL; Sheldrick, 1997)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.267
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             568
_exptl_crystal_size_max          0.46
_exptl_crystal_size_mid          0.25
_exptl_crystal_size_min          0.11
_refine_diff_density_max         0.15
_refine_diff_density_min         -0.17
_refine_ls_extinction_coef       0.022(4)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL97
_refine_ls_goodness_of_fit_ref   1.06
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     173
_refine_ls_number_reflns         1424
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.06
_refine_ls_R_factor_all          0.072
_refine_ls_R_factor_gt           0.050
_refine_ls_shift/su_max          0.00
_refine_ls_shift/su_mean         0.00
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.049P)^2^+0.3537P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.116
_refine_ls_wR_factor_ref         0.128
_reflns_number_gt                1065
_reflns_number_total             1424
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            fr1475.cif
_cod_data_source_block           I
_cod_depositor_comments
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The following automatic conversions were performed:
'_symmetry_cell_setting' value 'Orthorhombic' changed to 'orthorhombic'
according to '/home/saulius/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 1527 2010-12-29 10:47:43Z saulius 

The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Orthorhombic' changed to
'orthorhombic' according to
/home/saulius/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_values 1715 2011-07-08 13:25:40Z adriana 
;
_cod_database_code               2013986
_cod_database_fobs_code          2013986