The first facile stereoselectivity switch in the polymerization of rac-lactide‒from heteroselective dialkylgallium alkoxides to isoselective dialkylgallium alkoxides stabilized with NHC carbenes
Pawel Horeglad; Grzegorz Szczepaniak; Maciej Dranka; Janusz Zachara; Chem.Commun. 48 (2012) 1171–; doi:10.1039/c2cc16072b

data_7107217
_publ_section_title
;
 The first facile stereoselectivity switch in the polymerization of
 rac-lactide--from heteroselective dialkylgallium alkoxides to
 isoselective dialkylgallium alkoxides stabilized with NHC carbenes
;
_journal_name_full               Chem.Commun.
_journal_page_first              1171
_journal_paper_doi               10.1039/c2cc16072b
_journal_volume                  48
_journal_year                    2012
_chemical_absolute_configuration ad
_chemical_formula_moiety         'C24 H35 Ga N2 O'
_chemical_formula_sum            'C24 H35 Ga N2 O'
_chemical_formula_weight         437.26
_chemical_name_common
;(1,3-Dimesitylimidazolin-2-ylidene)-dimethyl-methoxy-
gallium(iii)
;
_chemical_name_systematic
;
(1,3-Dimesitylimidazolin-2-ylidene)-dimethyl-methoxy-gallium(iii)
;
_space_group_crystal_system      orthorhombic
_space_group_IT_number           33
_space_group_name_Hall           'P 2c -2n'
_space_group_name_H-M_alt        'P n a 21'
_symmetry_cell_setting           orthorhombic
_symmetry_Int_Tables_number      33
_symmetry_space_group_name_Hall  'P 2c -2n'
_symmetry_space_group_name_H-M   'P n a 21'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_date             2011-03-10
_audit_creation_method
;
Olex2 1.1
(compiled 2011.02.15 svn.r1672, GUI svn.r3494)
;
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   22.5330(4)
_cell_length_b                   7.78830(12)
_cell_length_c                   12.96404(20)
_cell_measurement_reflns_used    15137
_cell_measurement_temperature    100.0
_cell_measurement_theta_max      32.7668
_cell_measurement_theta_min      3.2637
_cell_volume                     2275.11(6)
_computing_cell_refinement
;
CrysAlisPro, Agilent Technologies,
Version 1.171.35.7 (release 14-02-2011 CrysAlis171 .NET)
(compiled Feb 15 2011,09:34:54)
;
_computing_data_collection
;
CrysAlisPro, Agilent Technologies,
Version 1.171.35.7 (release 14-02-2011 CrysAlis171 .NET)
(compiled Feb 15 2011,09:34:54)
;
_computing_data_reduction
;
CrysAlisPro, Agilent Technologies,
Version 1.171.35.7 (release 14-02-2011 CrysAlis171 .NET)
(compiled Feb 15 2011,09:34:54)
;
_computing_molecular_graphics
;
O. V. Dolomanov, L. J. Bourhis, R. J. Gildea, J. A. K. Howard and H. Puschmann,
OLEX2: a complete structure solution, refinement and analysis program.
J. Appl. Cryst. (2009). 42, 339-341.
;
_computing_publication_material
;
O. V. Dolomanov, L. J. Bourhis, R. J. Gildea, J. A. K. Howard and H. Puschmann,
OLEX2: a complete structure solution, refinement and analysis program.
J. Appl. Cryst. (2009). 42, 339-341.
;
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      100.0
_diffrn_detector_area_resol_mean 10.3347
_diffrn_measured_fraction_theta_full 0.942
_diffrn_measured_fraction_theta_max 0.942
_diffrn_measurement_details
;
1 omega -37.00 58.00 1.0000 8.0000
omega____ theta____ kappa____ phi______ frames
- -19.6509 77.0000 120.0000 95

2 omega -74.00 14.00 1.0000 8.0000
omega____ theta____ kappa____ phi______ frames
- -19.6509 -77.0000 0.0000 88

3 omega -32.00 -6.00 1.0000 8.0000
omega____ theta____ kappa____ phi______ frames
- -19.6509 77.0000 -30.0000 26

4 omega -53.00 43.00 1.0000 8.0000
omega____ theta____ kappa____ phi______ frames
- -19.6509 77.0000 -120.0000 96

5 omega -53.00 -15.00 1.0000 8.0000
omega____ theta____ kappa____ phi______ frames
- 19.9634 -38.0000 -150.0000 38

6 omega -19.00 10.00 1.0000 8.0000
omega____ theta____ kappa____ phi______ frames
- 19.9634 95.0000 -14.0000 29

7 omega 1.00 26.00 1.0000 8.0000
omega____ theta____ kappa____ phi______ frames
- 19.9634 -38.0000 -150.0000 25

8 omega 68.00 110.00 1.0000 8.0000
omega____ theta____ kappa____ phi______ frames
- 19.9634 179.0000 -120.0000 42
;
_diffrn_measurement_device_type  'Xcalibur, Atlas, Gemini ultra'
_diffrn_measurement_method       '\w scans'
_diffrn_orient_matrix_UB_11      -0.0104558000
_diffrn_orient_matrix_UB_12      -0.0695479000
_diffrn_orient_matrix_UB_13      -0.0302822000
_diffrn_orient_matrix_UB_21      0.0274585000
_diffrn_orient_matrix_UB_22      -0.0023828000
_diffrn_orient_matrix_UB_23      -0.0266922000
_diffrn_orient_matrix_UB_31      0.0112758000
_diffrn_orient_matrix_UB_32      -0.0587673000
_diffrn_orient_matrix_UB_33      0.0369398000
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0288
_diffrn_reflns_av_unetI/netI     0.0254
_diffrn_reflns_limit_h_max       34
_diffrn_reflns_limit_h_min       -31
_diffrn_reflns_limit_k_max       11
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -16
_diffrn_reflns_number            28944
_diffrn_reflns_theta_full        32.84
_diffrn_reflns_theta_max         32.84
_diffrn_reflns_theta_min         3.55
_diffrn_source                   'Enhance (Mo) X-ray Source'
_exptl_absorpt_coefficient_mu    1.225
_exptl_absorpt_correction_T_max  0.782
_exptl_absorpt_correction_T_min  0.666
_exptl_absorpt_correction_type   analytical
_exptl_absorpt_process_details
;
CrysAlisPro, Agilent Technologies,
Version 1.171.35.7 (release 14-02-2011 CrysAlis171 .NET)
(compiled Feb 15 2011,09:34:54)
Analytical numeric absorption correction using a multifaceted crystal
model based on expressions derived by R.C. Clark & J.S. Reid.
(Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897)
;
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.277
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prismatic
_exptl_crystal_F_000             928
_exptl_crystal_size_max          0.42
_exptl_crystal_size_mid          0.36
_exptl_crystal_size_min          0.25
_refine_diff_density_max         0.624
_refine_diff_density_min         -0.362
_refine_diff_density_rms         0.052
_refine_ls_abs_structure_details
;
2933 Friedel pairs recorded
;
_refine_ls_abs_structure_Flack   -0.005(6)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.051
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     262
_refine_ls_number_reflns         7072
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.051
_refine_ls_R_factor_all          0.0289
_refine_ls_R_factor_gt           0.0260
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0353P)^2^+0.4776P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0637
_refine_ls_wR_factor_ref         0.0655
_reflns_number_gt                6667
_reflns_number_total             7072
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            c2cc16072b.txt
_cod_data_source_block           2b
_cod_database_code               7107217