Bis(permethylpentalene)cerium‒another ambiguity in lanthanide oxidation state.
Ashley, Andrew; Balazs, Gabor; Cowley, Andrew; Green, Jennifer; Booth, Corwin H; O'Hare, Dermot; Chemical communications (Cambridge, England)  (2007) 1515–1517; doi:10.1039/b700303j

data_7101842
_publ_section_title
;
 Bis(permethylpentalene)cerium--another ambiguity in lanthanide
 oxidation state.
;
_journal_issue                   15
_journal_name_full
'Chemical communications (Cambridge, England)'
_journal_page_first              1515
_journal_page_last               1517
_journal_paper_doi               10.1039/b700303j
_journal_year                    2007
_chemical_absolute_configuration unk
_chemical_compound_source
;

synthesis as described

;
_chemical_formula_moiety         ' C28 H36 Ce '
_chemical_formula_sum            'C28 H36 Ce'
_chemical_formula_weight         512.71
_chemical_name_systematic
;

?

;
_space_group_IT_number           155
_symmetry_cell_setting           trigonal
_symmetry_space_group_name_Hall  'R 3 2"'
_symmetry_space_group_name_H-M   'R 3 2 :H'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     heavy
_atom_sites_solution_secondary   difmap
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                120
_cell_formula_units_Z            3
_cell_length_a                   9.4931(3)
_cell_length_b                   9.4931(3)
_cell_length_c                   22.1762(8)
_cell_measurement_reflns_used    2932
_cell_measurement_temperature    150
_cell_measurement_theta_max      28
_cell_measurement_theta_min      5
_cell_volume                     1730.75(10)
_computing_cell_refinement
;

KappaCCD software 'DENZO' (Otwinowski & Minor, 1996)

;
_computing_data_collection
;

KappaCCD software 'Collect' (Nonius, 2000)

;
_computing_data_reduction
;

KappaCCD software 'DENZO' (Otwinowski & Minor, 1996)

;
_computing_publication_material
;

CRYSTALS (Watkin et al, 2001)

;
_computing_structure_refinement
;

CRYSTALS (Watkin et al, 2001)

;
_diffrn_ambient_temperature      150
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type
;

Nonius KappaCCD

;
_diffrn_measurement_method       \w
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.034
_diffrn_reflns_limit_h_max       12
_diffrn_reflns_limit_h_min       -12
_diffrn_reflns_limit_k_max       6
_diffrn_reflns_limit_k_min       -6
_diffrn_reflns_limit_l_max       28
_diffrn_reflns_limit_l_min       -28
_diffrn_reflns_number            2932
_diffrn_reflns_theta_full        27.472
_diffrn_reflns_theta_max         27.472
_diffrn_reflns_theta_min         5.105
_diffrn_standards_decay_%        0.00
_diffrn_standards_interval_count 0
_diffrn_standards_interval_time  0
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    1.984
_exptl_absorpt_correction_T_max  0.94
_exptl_absorpt_correction_T_min  0.82
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;

Denzo/Scalepack (Otwinowski & Minor, 1996)

;
_exptl_crystal_colour            ' black '
_exptl_crystal_density_diffrn    1.476
_exptl_crystal_description       ' hexagonal plate '
_exptl_crystal_F_000             786
_exptl_crystal_size_max          0.10
_exptl_crystal_size_mid          0.10
_exptl_crystal_size_min          0.03
_exptl_crystal_thermal_history
;

The material was crystallised at ambient temperature. A suitable crystal

was cooled to 100K at a rate of 120 Khr^-1^ for single-crystal X-ray

diffraction analysis.

;
_refine_diff_density_max         0.72
_refine_diff_density_min         -1.01
_refine_ls_extinction_method     None
_refine_ls_goodness_of_fit_ref   0.9774
_refine_ls_hydrogen_treatment    noref
_refine_ls_matrix_type           full
_refine_ls_number_parameters     130
_refine_ls_number_reflns         520
_refine_ls_number_restraints     176
_refine_ls_R_factor_all          0.0267
_refine_ls_R_factor_gt           0.0267
_refine_ls_shift/su_max          0.040540
_refine_ls_structure_factor_coef F
_refine_ls_weighting_details
;

Method, part 1, Chebychev polynomial, (Watkin, 1994, Prince, 1982)

[weight] = 1.0/[A~0~*T~0~(x)+A~1~*T~1~(x) ... +A~n-1~]*T~n-1~(x)]

where A~i~ are the Chebychev coefficients listed below and x= Fcalc/Fmax

Method = Robust Weighting (Prince, 1982)

W = [weight] * [1-(deltaF/6*sigmaF)^2^]^2^

A~i~ are:

0.826 -0.389 0.485

;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_all         0.0282
_refine_ls_wR_factor_gt          0.0282
_refine_ls_wR_factor_ref         0.0282
_reflns_limit_h_max              0
_reflns_limit_h_min              -10
_reflns_limit_k_max              12
_reflns_limit_k_min              0
_reflns_limit_l_max              28
_reflns_limit_l_min              0
_reflns_number_gt                520
_reflns_number_total             520
_reflns_threshold_expression     I>3.00u(I)
_cod_data_source_file            b700303j.txt
_cod_data_source_block           arc1500
_cod_depositor_comments
;
The following automatic conversions were performed:
'_symmetry_cell_setting' value 'Trigonal' changed to 'trigonal' 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 
;
_cod_original_sg_symbol_H-M      'R 3 2 '
_cod_original_formula_sum        ' C28 H36 Ce '
_cod_database_code               7101842