Zwitterionic and free forms of arylmethyl Meldrum's acids.
Mierina, Inese; Mishnev, Anatoly; Jure, Mara; Acta crystallographica. Section C, Structural chemistry 71 (2015) 752–758; doi:10.1107/S2053229615014308

data_2311844
_publ_section_title
;
 Zwitterionic and free forms of arylmethyl Meldrum's acids.
;
_journal_coeditor_code           DT3032
_journal_issue                   'Pt 9'
_journal_name_full
'Acta crystallographica. Section C, Structural chemistry'
_journal_page_first              752
_journal_page_last               758
_journal_paper_doi               10.1107/S2053229615014308
_journal_volume                  71
_journal_year                    2015
_chemical_formula_iupac          'C16 H20 O7'
_chemical_formula_moiety         'C16 H20 O7'
_chemical_formula_sum            'C16 H20 O7'
_chemical_formula_weight         324.32
_chemical_name_systematic
;
2,2-Dimethyl-5-(2,4,6-trimethoxybenzyl)-1,3-dioxane-4,6-dione
;
_space_group_IT_number           61
_space_group_name_Hall           '-P 2ac 2ab'
_space_group_name_H-M_alt        'P b c a'
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  '-P 2ac 2ab'
_symmetry_space_group_name_H-M   'P b c a'
_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            8
_cell_length_a                   9.8128(2)
_cell_length_b                   10.0235(2)
_cell_length_c                   30.4669(6)
_cell_measurement_reflns_used    15283
_cell_measurement_temperature    190(2)
_cell_measurement_theta_max      27.485
_cell_measurement_theta_min      0.998
_cell_volume                     2996.68(10)
_computing_cell_refinement
;
SCALEPACK (Otwinowski & Minor, 1997)
;
_computing_data_collection
;
COLLECT (Bruker, 2004)
;
_computing_data_reduction
;
DENZO (Otwinowski & Minor, 1997)
;
_computing_molecular_graphics
;
ORTEP-3 for Windows (Farrugia, 2012)
;
_computing_publication_material
;
SHELXL97 (Sheldrick, 2008)
;
_computing_structure_refinement
;
SHELXL97 (Sheldrick, 2008)
;
_computing_structure_solution
;
SHELXS97 (Sheldrick, 2008)
;
_diffrn_ambient_temperature      190(2)
_diffrn_measured_fraction_theta_full 0.990
_diffrn_measured_fraction_theta_max 0.990
_diffrn_measurement_device_type  'Nonius KappaCCD'
_diffrn_measurement_method       CCD
_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  0.0401
_diffrn_reflns_av_sigmaI/netI    0.0548
_diffrn_reflns_limit_h_max       12
_diffrn_reflns_limit_h_min       -12
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       39
_diffrn_reflns_limit_l_min       -39
_diffrn_reflns_number            6059
_diffrn_reflns_theta_full        27.41
_diffrn_reflns_theta_max         27.41
_diffrn_reflns_theta_min         2.47
_exptl_absorpt_coefficient_mu    0.113
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.438
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             1376
_exptl_crystal_size_max          0.26
_exptl_crystal_size_mid          0.24
_exptl_crystal_size_min          0.10
_refine_diff_density_max         0.269
_refine_diff_density_min         -0.239
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.997
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     213
_refine_ls_number_reflns         3374
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.997
_refine_ls_R_factor_all          0.0689
_refine_ls_R_factor_gt           0.0421
_refine_ls_shift/su_max          0.009
_refine_ls_shift/su_mean         0.002
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0465P)^2^+0.7724P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0942
_refine_ls_wR_factor_ref         0.1052
_reflns_number_gt                2421
_reflns_number_total             3374
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            dt3032sup1.cif
_cod_data_source_block           II
_cod_database_code               2311844