Exploring the solid state and solution structural chemistry of the utility amide potassium hexamethyldisilazide (KHMDS)
Ojeda-Amador, Ana I.; Martínez-Martínez, Antonio J.; Robertson, Gemma M.; Robertson, Stuart D.; Kennedy, Alan R.; O'Hara, Charles T.; Dalton Trans.  (2017) –; doi:10.1039/C7DT01118K

data_7042876
_publ_section_title
;
 Exploring the solid state and solution structural chemistry of the
 utility amide potassium hexamethyldisilazide (KHMDS)
;
_journal_name_full               'Dalton Trans.'
_journal_paper_doi               10.1039/C7DT01118K
_journal_year                    2017
_chemical_absolute_configuration rmad
_chemical_formula_moiety         'C32 H80 K2 N6 Si4'
_chemical_formula_sum            'C32 H80 K2 N6 Si4'
_chemical_formula_weight         739.58
_chemical_properties_physical
', Air-sensitive,Moisture-sensitive,Oxygen-sensitive'
_space_group_crystal_system      orthorhombic
_space_group_IT_number           19
_space_group_name_Hall           'P 2ac 2ab'
_space_group_name_H-M_alt        'P 21 21 21'
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2014/7
_audit_update_record
;
2017-03-14 deposited with the CCDC.
2017-04-17 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   11.8251(2)
_cell_length_b                   11.9313(3)
_cell_length_c                   32.6567(8)
_cell_measurement_reflns_used    9761
_cell_measurement_temperature    123(2)
_cell_measurement_theta_max      30.2200
_cell_measurement_theta_min      3.4570
_cell_volume                     4607.50(18)
_computing_cell_refinement
;
CrysAlisPro, Agilent Technologies,
Version 1.171.37.35 (release 13-08-2014 CrysAlis171 .NET)
(compiled Aug 13 2014,18:06:01)
;
_computing_data_collection
;
CrysAlisPro, Agilent Technologies,
Version 1.171.37.35 (release 13-08-2014 CrysAlis171 .NET)
(compiled Aug 13 2014,18:06:01)
;
_computing_data_reduction
;
CrysAlisPro, Agilent Technologies,
Version 1.171.37.35 (release 13-08-2014 CrysAlis171 .NET)
(compiled Aug 13 2014,18:06:01)
;
_computing_structure_refinement  'SHELXL-2014/7 (Sheldrick, 2014)'
_diffrn_ambient_temperature      123(2)
_diffrn_measured_fraction_theta_full 0.994
_diffrn_measured_fraction_theta_max 0.994
_diffrn_measurement_device_type  'OD Gemini S'
_diffrn_measurement_method       'omega scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0295
_diffrn_reflns_av_unetI/netI     0.0397
_diffrn_reflns_Laue_measured_fraction_full 0.994
_diffrn_reflns_Laue_measured_fraction_max 0.994
_diffrn_reflns_limit_h_max       15
_diffrn_reflns_limit_h_min       -15
_diffrn_reflns_limit_k_max       15
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       40
_diffrn_reflns_limit_l_min       -41
_diffrn_reflns_number            26058
_diffrn_reflns_point_group_measured_fraction_full 0.991
_diffrn_reflns_point_group_measured_fraction_max 0.991
_diffrn_reflns_theta_full        26.995
_diffrn_reflns_theta_max         26.995
_diffrn_reflns_theta_min         3.023
_diffrn_source                   'sealed tube'
_exptl_absorpt_coefficient_mu    0.336
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.99038
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
CrysAlisPro, Agilent Technologies,
Version 1.171.37.35 (release 13-08-2014 CrysAlis171 .NET)
(compiled Aug 13 2014,18:06:01)
Empirical absorption correction using spherical harmonics,
 implemented in SCALE3 ABSPACK scaling algorithm.
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.066
_exptl_crystal_description       block
_exptl_crystal_F_000             1632
_exptl_crystal_size_max          0.32
_exptl_crystal_size_mid          0.26
_exptl_crystal_size_min          0.18
_refine_diff_density_max         0.271
_refine_diff_density_min         -0.193
_refine_diff_density_rms         0.042
_refine_ls_abs_structure_details
;
 Flack x determined using 3688 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   0.009(15)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.099
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     417
_refine_ls_number_reflns         9964
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.099
_refine_ls_R_factor_all          0.0411
_refine_ls_R_factor_gt           0.0368
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0303P)^2^+0.8525P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0753
_refine_ls_wR_factor_ref         0.0771
_reflns_Friedel_coverage         0.791
_reflns_Friedel_fraction_full    0.987
_reflns_Friedel_fraction_max     0.987
_reflns_number_gt                9328
_reflns_number_total             9964
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c7dt01118k2.cif
_cod_data_source_block           amao_ktmcda
_cod_database_code               7042876
_shelx_shelxl_version_number     2014/7
_shelx_res_checksum              37525