The square-planar to flattened-tetrahedral CuX42−(X= Cl, Br) structural phase transition in 1,2,6-trimethylpyridinium salts
Kelley, Annette; Nalla, Sowjanya; Bond, Marcus R.; Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 71 (2015) 48–60; doi:10.1107/S205252061402664X

data_2020872
_publ_section_title
;
 The square-planar to flattened-tetrahedral CuX42&#x2212;(X= Cl, Br)
 structural phase transition in 1,2,6-trimethylpyridinium salts
;
_journal_coeditor_code           OG5072
_journal_issue                   1
_journal_name_full
'Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials'
_journal_page_first              48
_journal_page_last               60
_journal_paper_doi               10.1107/S205252061402664X
_journal_volume                  71
_journal_year                    2015
_chemical_formula_moiety         '2(C8 H12 N), Br4 Cu'
_chemical_formula_sum            'C16 H24 Br4 Cu N2'
_chemical_formula_weight         627.55
_chemical_name_systematic
;
bis(1,2,6-trimethylpyridinium) tetrabromidocuprate(II)
;
_space_group_crystal_system      triclinic
_space_group_IT_number           2
_space_group_name_Hall           '-P 1'
_space_group_name_H-M_alt        'P -1'
_symmetry_space_group_name_Hall  '-P 1'
_symmetry_space_group_name_H-M   'P -1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_cell_angle_alpha                75.997(2)
_cell_angle_beta                 88.567(2)
_cell_angle_gamma                65.757(2)
_cell_formula_units_Z            2
_cell_length_a                   8.0517(2)
_cell_length_b                   9.3247(3)
_cell_length_c                   16.4524(5)
_cell_measurement_reflns_used    4896
_cell_measurement_temperature    295(2)
_cell_measurement_theta_max      27.485
_cell_measurement_theta_min      2.91
_cell_volume                     1088.97(6)
_computing_cell_refinement       'HKL Scalepack (Otwinowski & Minor 1997)'
_computing_data_collection       'Collect (Bruker AXS BV, 1997-2004)'
_computing_data_reduction
'HKL Denzo and Scalepack (Otwinowski & Minor 1997)'
_computing_molecular_graphics    'Ortep-3 for Windows (Farrugia, 1997)'
_computing_publication_material  'WinGX publication routines (Farrugia, 1999)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      295(2)
_diffrn_detector_area_resol_mean 9
_diffrn_measured_fraction_theta_full 0.993
_diffrn_measured_fraction_theta_max 0.993
_diffrn_measurement_device       '95mm CCD camera on \k-goniostat'
_diffrn_measurement_device_type  KappaCCD
_diffrn_measurement_method       'CCD rotation images, thick slices'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0336
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       21
_diffrn_reflns_limit_l_min       -21
_diffrn_reflns_number            19577
_diffrn_reflns_reduction_process
;
 Scaled and merged with Sortav
 R.H. Blessing, (1987) Cryst. Rev. 1, 3-58
 R.H. Blessing, (1989) J. Appl. Cryst. 22, 396-397
;
_diffrn_reflns_theta_full        27.46
_diffrn_reflns_theta_max         27.46
_diffrn_reflns_theta_min         4.96
_exptl_absorpt_coefficient_mu    8.341
_exptl_absorpt_correction_T_max  0.441
_exptl_absorpt_correction_T_min  0.283
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   '(DENZO/SCALEPACK; Otwinowski & Minor, 1997)'
_exptl_crystal_colour            'dark purple'
_exptl_crystal_density_diffrn    1.914
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             606
_exptl_crystal_size_max          0.175
_exptl_crystal_size_mid          0.130
_exptl_crystal_size_min          0.085
_refine_diff_density_max         1.023
_refine_diff_density_min         -1.17
_refine_ls_extinction_coef       0.0180(7)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   1.034
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     215
_refine_ls_number_reflns         4944
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.034
_refine_ls_R_factor_all          0.0684
_refine_ls_R_factor_gt           0.0378
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0263P)^2^+1.3223P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0764
_refine_ls_wR_factor_ref         0.0886
_reflns_number_gt                3455
_reflns_number_total             4944
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            og5072sup1_Br295K.cif
_cod_data_source_block           Br295K
_cod_database_code               2020872
_cod_database_fobs_code 2020872