Supplementary Material (ESI) for Dalton Transactions This journal is (c) The Royal Society of Chemistry 2001 data_global _journal_coden_Cambridge 186 _publ_requested_journal 'Dalton Transactions' loop_ _publ_author_name 'David W. H. Rankin' _publ_contact_author_name 'David W.H.Rankin' _publ_contact_author_address ; Prof D Rankin Department of Chemistry University of Edinburgh West Mains Road Edinburgh EH9 3JJ UK ; _publ_contact_author_email 'D.W.H.RANKIN@ED.AC.UK' data_1,2-di-butyltetrachlorodisilane _database_code_CSD 169479 _audit_creation_method SHELXL-97 _chemical_name_systematic ; ? ; _chemical_name_common '1,2-di-butyltetrachlorodisilane' _chemical_melting_point ? _chemical_formula_moiety 'tBuCl2SiSiCl2tBu' _chemical_formula_sum 'C8 H18 Cl4 Si2' _chemical_formula_weight 312.20 loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source 'C' 'C' 0.0033 0.0016 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'H' 'H' 0.0000 0.0000 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'Si' 'Si' 0.0817 0.0704 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'Cl' 'Cl' 0.1484 0.1585 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' _symmetry_cell_setting Triclinic _symmetry_space_group_name_H-M P-1 loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x, -y, -z' _cell_length_a 6.7183(17) _cell_length_b 7.5290(19) _cell_length_c 8.789(2) _cell_angle_alpha 94.93(4) _cell_angle_beta 107.60(3) _cell_angle_gamma 112.43(4) _cell_volume 381.35(16) _cell_formula_units_Z 1 _cell_measurement_temperature 150(2) _cell_measurement_reflns_used 1828 _cell_measurement_theta_min 5 _cell_measurement_theta_max 52 _exptl_crystal_description Cylinder _exptl_crystal_colour colourless _exptl_crystal_size_max 0.40 _exptl_crystal_size_mid 0.17 _exptl_crystal_size_min 0.17 _exptl_crystal_density_meas ? _exptl_crystal_density_diffrn 1.359 _exptl_crystal_density_method 'not measured' _exptl_crystal_F_000 162 _exptl_absorpt_coefficient_mu 0.901 _exptl_absorpt_correction_type 'Empirical' _exptl_absorpt_correction_T_min 0.533 _exptl_absorpt_correction_T_max 0.962 _exptl_absorpt_process_details ? _exptl_special_details ; ? ; _diffrn_ambient_temperature 150(2) _diffrn_radiation_wavelength 0.71073 _diffrn_radiation_type MoK\a _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_monochromator graphite _diffrn_measurement_device_type 'CCD area detector' _diffrn_measurement_method 'phi and omega scans' _diffrn_detector_area_resol_mean ? _diffrn_standards_number 0 _diffrn_standards_interval_count ? _diffrn_standards_interval_time ? _diffrn_standards_decay_% 0 _diffrn_reflns_number 2182 _diffrn_reflns_av_R_equivalents 0.0245 _diffrn_reflns_av_sigmaI/netI 0.0522 _diffrn_reflns_limit_h_min -7 _diffrn_reflns_limit_h_max 8 _diffrn_reflns_limit_k_min -9 _diffrn_reflns_limit_k_max 8 _diffrn_reflns_limit_l_min -10 _diffrn_reflns_limit_l_max 10 _diffrn_reflns_theta_min 2.50 _diffrn_reflns_theta_max 26.36 _reflns_number_total 1420 _reflns_number_gt 1155 _reflns_threshold_expression >2sigma(I) _computing_data_collection 'Bruker SMART' _computing_cell_refinement 'Bruker SMART' _computing_data_reduction 'Bruker SHELXTL' _computing_structure_solution 'SHELXS-97 (Sheldrick, 1990)' _computing_structure_refinement 'SHELXL-97 (Sheldrick, 1997)' _computing_molecular_graphics 'Bruker SHELXTL' _computing_publication_material SHELXTL _refine_special_details ; Refinement of F^2^ against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The threshold expression of F^2^ > 2sigma(F^2^) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. ; _refine_ls_structure_factor_coef Fsqd _refine_ls_matrix_type full _refine_ls_weighting_scheme calc _refine_ls_weighting_details 'calc w=1/[\s^2^(Fo^2^)+(0.0490P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3' _atom_sites_solution_primary direct _atom_sites_solution_secondary difmap _atom_sites_solution_hydrogens geom _refine_ls_hydrogen_treatment 'riding, rotation groups Me' _refine_ls_extinction_method none _refine_ls_extinction_coef ? _refine_ls_number_reflns 1420 _refine_ls_number_parameters 67 _refine_ls_number_restraints 0 _refine_ls_R_factor_all 0.0411 _refine_ls_R_factor_gt 0.0380 _refine_ls_wR_factor_ref 0.0933 _refine_ls_wR_factor_gt 0.0925 _refine_ls_goodness_of_fit_ref 0.944 _refine_ls_restrained_S_all 0.944 _refine_ls_shift/su_max 0.000 _refine_ls_shift/su_mean 0.000 loop_ _atom_site_label _atom_site_type_symbol _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_adp_type _atom_site_occupancy _atom_site_symmetry_multiplicity _atom_site_calc_flag _atom_site_refinement_flags _atom_site_disorder_assembly _atom_site_disorder_group Si1 Si 0.48407(12) 0.47997(10) 0.86104(8) 0.0248(2) Uani 1 1 d . . . Cl1 Cl 0.21171(12) 0.53937(11) 0.73409(8) 0.0388(2) Uani 1 1 d . . . Cl2 Cl 0.78038(11) 0.69813(10) 0.85511(8) 0.0383(2) Uani 1 1 d . . . C1 C 0.4400(5) 0.2347(4) 0.7509(3) 0.0308(6) Uani 1 1 d . . . C2 C 0.4362(6) 0.2462(5) 0.5752(3) 0.0446(8) Uani 1 1 d . . . H2A H 0.5857 0.3453 0.5808 0.067 Uiso 1 1 calc R . . H2B H 0.3135 0.2833 0.5179 0.067 Uiso 1 1 calc R . . H2C H 0.4070 0.1172 0.5157 0.067 Uiso 1 1 calc R . . C3 C 0.6408(6) 0.1850(5) 0.8418(3) 0.0470(8) Uani 1 1 d . . . H3A H 0.6208 0.0603 0.7809 0.070 Uiso 1 1 calc R . . H3B H 0.6412 0.1723 0.9520 0.070 Uiso 1 1 calc R . . H3C H 0.7878 0.2907 0.8504 0.070 Uiso 1 1 calc R . . C4 C 0.2085(5) 0.0736(4) 0.7423(3) 0.0455(8) Uani 1 1 d . . . H4A H 0.1853 -0.0540 0.6844 0.068 Uiso 1 1 calc R . . H4B H 0.0820 0.1057 0.6833 0.068 Uiso 1 1 calc R . . H4C H 0.2109 0.0667 0.8536 0.068 Uiso 1 1 calc R . . loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_23 _atom_site_aniso_U_13 _atom_site_aniso_U_12 Si1 0.0288(4) 0.0279(4) 0.0216(4) 0.0105(3) 0.0119(3) 0.0129(3) Cl1 0.0421(4) 0.0507(5) 0.0318(4) 0.0142(3) 0.0105(3) 0.0293(4) Cl2 0.0381(4) 0.0390(4) 0.0356(4) 0.0143(3) 0.0203(3) 0.0078(3) C1 0.0409(16) 0.0323(15) 0.0229(13) 0.0077(12) 0.0136(12) 0.0175(13) C2 0.069(2) 0.0432(19) 0.0280(14) 0.0079(13) 0.0207(15) 0.0287(17) C3 0.065(2) 0.050(2) 0.0402(16) 0.0140(15) 0.0189(15) 0.0394(18) C4 0.055(2) 0.0304(17) 0.0422(17) 0.0044(14) 0.0160(15) 0.0106(15) _geom_special_details ; All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. ; loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_distance _geom_bond_site_symmetry_2 _geom_bond_publ_flag Si1 C1 1.881(3) . ? Si1 Cl2 2.0605(15) . ? Si1 Cl1 2.0660(11) . ? Si1 Si1 2.3689(14) 2_667 ? C1 C4 1.539(4) . ? C1 C3 1.544(3) . ? C1 C2 1.547(3) . ? loop_ _geom_angle_atom_site_label_1 _geom_angle_atom_site_label_2 _geom_angle_atom_site_label_3 _geom_angle _geom_angle_site_symmetry_1 _geom_angle_site_symmetry_3 _geom_angle_publ_flag C1 Si1 Cl2 109.26(10) . . ? C1 Si1 Cl1 108.26(9) . . ? Cl2 Si1 Cl1 106.95(5) . . ? C1 Si1 Si1 118.21(9) . 2_667 ? Cl2 Si1 Si1 106.41(7) . 2_667 ? Cl1 Si1 Si1 107.23(5) . 2_667 ? C4 C1 C3 110.1(2) . . ? C4 C1 C2 109.5(2) . . ? C3 C1 C2 108.8(2) . . ? C4 C1 Si1 109.51(19) . . ? C3 C1 Si1 109.90(18) . . ? C2 C1 Si1 109.07(18) . . ? _diffrn_measured_fraction_theta_max 0.912 _diffrn_reflns_theta_full 26.36 _diffrn_measured_fraction_theta_full 0.912 _refine_diff_density_max 0.688 _refine_diff_density_min -0.321 _refine_diff_density_rms 0.077 data_1,2-di-butyltetrabromodisilane _database_code_CSD 169480 _audit_creation_method SHELXL _chemical_name_systematic ; ? ; _chemical_name_common '1,2-di-butyltetrabromodisilane ' _chemical_formula_moiety ? _chemical_formula_structural ? _chemical_formula_analytical ? _chemical_formula_sum 'C8 H18 Br4 Si2' _chemical_formula_weight 490.04 _chemical_melting_point ? _chemical_compound_source ? loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source 'C' 'C' 0.0033 0.0016 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'H' 'H' 0.0000 0.0000 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'Si' 'Si' 0.0817 0.0704 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'Br' 'Br' -0.2901 2.4595 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' _symmetry_cell_setting ? _symmetry_space_group_name_H-M ? loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x, -y, -z' _cell_length_a 7.0720(10) _cell_length_b 7.637(2) _cell_length_c 8.827(2) _cell_angle_alpha 96.49(3) _cell_angle_beta 108.36(3) _cell_angle_gamma 114.02(3) _cell_volume 396.96(15) _cell_formula_units_Z 1 _cell_measurement_temperature 293(2) _cell_measurement_reflns_used ? _cell_measurement_theta_min ? _cell_measurement_theta_max ? _exptl_crystal_description ? _exptl_crystal_colour ? _exptl_crystal_size_max ? _exptl_crystal_size_mid ? _exptl_crystal_size_min ? _exptl_crystal_density_meas ? _exptl_crystal_density_diffrn 2.050 _exptl_crystal_density_method ? _exptl_crystal_F_000 234 _exptl_absorpt_coefficient_mu 10.259 _exptl_absorpt_correction_type ? _exptl_absorpt_correction_T_min ? _exptl_absorpt_correction_T_max ? _exptl_special_details ; ? ; _diffrn_ambient_temperature 293(2) _diffrn_radiation_wavelength 0.71073 _diffrn_radiation_type MoK\a _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_monochromator graphite _diffrn_measurement_device ? _diffrn_measurement_method ? _diffrn_standards_number ? _diffrn_standards_interval_count ? _diffrn_standards_interval_time ? _diffrn_standards_decay_% ? _diffrn_reflns_number 2709 _diffrn_reflns_av_R_equivalents 0.0459 _diffrn_reflns_av_sigmaI/netI 0.0537 _diffrn_reflns_limit_h_min -9 _diffrn_reflns_limit_h_max 9 _diffrn_reflns_limit_k_min -10 _diffrn_reflns_limit_k_max 10 _diffrn_reflns_limit_l_min -12 _diffrn_reflns_limit_l_max 12 _diffrn_reflns_theta_min 3.04 _diffrn_reflns_theta_max 30.00 _reflns_number_total 2303 _reflns_number_observed 1853 _reflns_observed_criterion >2sigma(I) _computing_data_collection ? _computing_cell_refinement ? _computing_data_reduction ? _computing_structure_solution 'SHELXS-86 (Sheldrick, 1990)' _computing_structure_refinement 'SHELXL-93 (Sheldrick, 1993)' _computing_molecular_graphics ? _computing_publication_material ? _refine_special_details ; Refinement on F^2^ for ALL reflections except for 2 with very negative F^2^ or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The observed criterion of F^2^ > 2sigma(F^2^) is used only for calculating _R_factor_obs etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. ; _refine_ls_structure_factor_coef Fsqd _refine_ls_matrix_type full _refine_ls_weighting_scheme 'calc w=1/[\s^2^(Fo^2^)+(0.1000P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3' _atom_sites_solution_primary direct _atom_sites_solution_secondary difmap _atom_sites_solution_hydrogens geom _refine_ls_hydrogen_treatment ? _refine_ls_extinction_method none _refine_ls_extinction_coef ? _refine_ls_number_reflns 2301 _refine_ls_number_parameters 67 _refine_ls_number_restraints 0 _refine_ls_R_factor_all 0.0924 _refine_ls_R_factor_obs 0.0704 _refine_ls_wR_factor_all 0.1902 _refine_ls_wR_factor_obs 0.1696 _refine_ls_goodness_of_fit_all 1.303 _refine_ls_goodness_of_fit_obs 1.300 _refine_ls_restrained_S_all 1.307 _refine_ls_restrained_S_obs 1.300 _refine_ls_shift/esd_max -3.387 _refine_ls_shift/esd_mean 0.065 loop_ _atom_site_label _atom_site_type_symbol _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_thermal_displace_type _atom_site_occupancy _atom_site_calc_flag _atom_site_refinement_flags _atom_site_disorder_group Br1 Br 0.20655(12) 0.28060(11) 0.13615(9) 0.0161(2) Uani 1 d . . Br2 Br 0.80788(12) 0.48150(11) 0.28152(8) 0.0156(2) Uani 1 d . . Si1 Si 0.5162(3) 0.5255(3) 0.1386(2) 0.0073(4) Uani 1 d . . C1 C 0.5588(12) 0.7732(10) 0.2529(8) 0.0095(12) Uani 1 d . . C2 C 0.3608(14) 0.8105(12) 0.1577(10) 0.019(2) Uani 1 d . . H2A H 0.3702(94) 0.9249(88) 0.2239(51) 0.080 Uiso 1 calc R . H2B H 0.2204(14) 0.6957(59) 0.1352(107) 0.080 Uiso 1 calc R . H2C H 0.3686(95) 0.8341(144) 0.0548(56) 0.080 Uiso 1 calc R . C3 C 0.7800(15) 0.9414(11) 0.2645(10) 0.022(2) Uani 1 d . . H3A H 0.8020(84) 1.0666(20) 0.3228(108) 0.080 Uiso 1 calc R . H3B H 0.7736(66) 0.9447(95) 0.1546(10) 0.080 Uiso 1 calc R . H3C H 0.9034(23) 0.9183(79) 0.3233(108) 0.080 Uiso 1 calc R . C4 C 0.5695(15) 0.7614(12) 0.4280(9) 0.018(2) Uani 1 d . . H4A H 0.5910(170) 0.8849(55) 0.4892(43) 0.080 Uiso 1 calc R . H4B H 0.6932(104) 0.7376(149) 0.4847(46) 0.080 Uiso 1 calc R . H4C H 0.4310(67) 0.6542(96) 0.4194(9) 0.080 Uiso 1 calc R . loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_23 _atom_site_aniso_U_13 _atom_site_aniso_U_12 Br1 0.0123(4) 0.0184(4) 0.0071(3) 0.0017(3) 0.0006(3) 0.0005(3) Br2 0.0137(4) 0.0246(4) 0.0046(3) 0.0006(3) -0.0058(3) 0.0133(3) Si1 0.0068(8) 0.0092(8) 0.0000(7) -0.0021(6) -0.0045(6) 0.0037(7) C1 0.010(3) 0.012(3) 0.000(3) -0.005(2) -0.003(2) 0.005(2) C2 0.025(4) 0.023(4) 0.009(3) -0.001(3) 0.000(3) 0.017(3) C3 0.022(4) 0.013(3) 0.015(4) -0.006(3) -0.003(3) 0.003(3) C4 0.026(4) 0.024(4) 0.000(3) -0.003(3) 0.000(3) 0.014(3) _geom_special_details ; All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. ; loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_distance _geom_bond_site_symmetry_2 _geom_bond_publ_flag Br1 Si1 2.218(2) . ? Br2 Si1 2.232(2) . ? Si1 C1 1.897(7) . ? Si1 Si1 2.355(4) 2_665 ? C1 C3 1.530(11) . ? C1 C4 1.538(10) . ? C1 C2 1.545(10) . ? loop_ _geom_angle_atom_site_label_1 _geom_angle_atom_site_label_2 _geom_angle_atom_site_label_3 _geom_angle _geom_angle_site_symmetry_1 _geom_angle_site_symmetry_3 _geom_angle_publ_flag C1 Si1 Br1 109.3(2) . . ? C1 Si1 Br2 107.8(2) . . ? Br1 Si1 Br2 107.57(9) . . ? C1 Si1 Si1 119.2(2) . 2_665 ? Br1 Si1 Si1 106.06(12) . 2_665 ? Br2 Si1 Si1 106.46(12) . 2_665 ? C3 C1 C4 110.1(6) . . ? C3 C1 C2 109.3(6) . . ? C4 C1 C2 110.9(6) . . ? C3 C1 Si1 109.4(5) . . ? C4 C1 Si1 107.4(5) . . ? C2 C1 Si1 109.6(5) . . ? loop_ _geom_torsion_atom_site_label_1 _geom_torsion_atom_site_label_2 _geom_torsion_atom_site_label_3 _geom_torsion_atom_site_label_4 _geom_torsion _geom_torsion_site_symmetry_1 _geom_torsion_site_symmetry_2 _geom_torsion_site_symmetry_3 _geom_torsion_site_symmetry_4 _geom_torsion_publ_flag Br1 Si1 C1 C3 176.5(4) . . . . ? Br2 Si1 C1 C3 59.9(5) . . . . ? Si1 Si1 C1 C3 -61.5(5) 2_665 . . . ? Br1 Si1 C1 C4 56.9(5) . . . . ? Br2 Si1 C1 C4 -59.7(5) . . . . ? Si1 Si1 C1 C4 179.0(4) 2_665 . . . ? Br1 Si1 C1 C2 -63.7(5) . . . . ? Br2 Si1 C1 C2 179.7(4) . . . . ? Si1 Si1 C1 C2 58.4(6) 2_665 . . . ? C1 Si1 Si1 C1 180.0 . . 2_665 2_665 ? _refine_diff_density_max 2.540 _refine_diff_density_min -2.597 _refine_diff_density_rms 0.366 data_1,2-di-butyltetraiododisilane _database_code_CSD 169481 _audit_creation_method SHELXL-97 _chemical_name_systematic ; ? ; _chemical_name_common '1,2-di-butyltetraiododisilane' _chemical_melting_point ? _chemical_formula_moiety ? _chemical_formula_sum 'C8 H18 I4 Si2' _chemical_formula_weight 678.00 loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source 'C' 'C' 0.0033 0.0016 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'H' 'H' 0.0000 0.0000 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'Si' 'Si' 0.0817 0.0704 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'I' 'I' -0.4742 1.8119 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' _symmetry_cell_setting ? _symmetry_space_group_name_H-M ? loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x, -y, -z' _cell_length_a 7.639(2) _cell_length_b 8.033(2) _cell_length_c 8.854(2) _cell_angle_alpha 100.11(3) _cell_angle_beta 106.83(3) _cell_angle_gamma 114.77(3) _cell_volume 443.80(19) _cell_formula_units_Z 1 _cell_measurement_temperature 293(2) _cell_measurement_reflns_used ? _cell_measurement_theta_min ? _cell_measurement_theta_max ? _exptl_crystal_description ? _exptl_crystal_colour ? _exptl_crystal_size_max ? _exptl_crystal_size_mid ? _exptl_crystal_size_min ? _exptl_crystal_density_meas ? _exptl_crystal_density_diffrn 2.537 _exptl_crystal_density_method 'not measured' _exptl_crystal_F_000 306 _exptl_absorpt_coefficient_mu 7.130 _exptl_absorpt_correction_type ? _exptl_absorpt_correction_T_min ? _exptl_absorpt_correction_T_max ? _exptl_absorpt_process_details ? _exptl_special_details ; ? ; _diffrn_ambient_temperature 293(2) _diffrn_radiation_wavelength 0.71073 _diffrn_radiation_type MoK\a _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_monochromator graphite _diffrn_measurement_device_type ? _diffrn_measurement_method ? _diffrn_detector_area_resol_mean ? _diffrn_standards_number ? _diffrn_standards_interval_count ? _diffrn_standards_interval_time ? _diffrn_standards_decay_% ? _diffrn_reflns_number 4467 _diffrn_reflns_av_R_equivalents 0.0241 _diffrn_reflns_av_sigmaI/netI 0.0232 _diffrn_reflns_limit_h_min -12 _diffrn_reflns_limit_h_max 11 _diffrn_reflns_limit_k_min -12 _diffrn_reflns_limit_k_max 12 _diffrn_reflns_limit_l_min -12 _diffrn_reflns_limit_l_max 14 _diffrn_reflns_theta_min 2.97 _diffrn_reflns_theta_max 34.97 _reflns_number_total 3869 _reflns_number_gt 3522 _reflns_threshold_expression >2sigma(I) _computing_data_collection ? _computing_cell_refinement ? _computing_data_reduction ? _computing_structure_solution 'SHELXS-97 (Sheldrick, 1990)' _computing_structure_refinement 'SHELXL-97 (Sheldrick, 1997)' _computing_molecular_graphics ? _computing_publication_material ? _refine_special_details ; Refinement of F^2^ against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The threshold expression of F^2^ > 2sigma(F^2^) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. ; _refine_ls_structure_factor_coef Fsqd _refine_ls_matrix_type full _refine_ls_weighting_scheme calc _refine_ls_weighting_details 'calc w=1/[\s^2^(Fo^2^)+(0.1092P)^2^+2.0400P] where P=(Fo^2^+2Fc^2^)/3' _atom_sites_solution_primary direct _atom_sites_solution_secondary difmap _atom_sites_solution_hydrogens geom _refine_ls_hydrogen_treatment mixed _refine_ls_extinction_method none _refine_ls_extinction_coef ? _refine_ls_number_reflns 3869 _refine_ls_number_parameters 67 _refine_ls_number_restraints 0 _refine_ls_R_factor_all 0.0661 _refine_ls_R_factor_gt 0.0618 _refine_ls_wR_factor_ref 0.1718 _refine_ls_wR_factor_gt 0.1669 _refine_ls_goodness_of_fit_ref 1.171 _refine_ls_restrained_S_all 1.171 _refine_ls_shift/su_max 0.001 _refine_ls_shift/su_mean 0.000 loop_ _atom_site_label _atom_site_type_symbol _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_adp_type _atom_site_occupancy _atom_site_symmetry_multiplicity _atom_site_calc_flag _atom_site_refinement_flags _atom_site_disorder_assembly _atom_site_disorder_group I1 I 0.79474(5) 0.68858(5) 0.83971(4) 0.01944(11) Uani 1 1 d . . . I2 I 0.17497(5) 0.47695(5) 0.69528(4) 0.01868(11) Uani 1 1 d . . . Si1 Si 0.47718(19) 0.44879(19) 0.85864(15) 0.0095(2) Uani 1 1 d . . . C1 C 0.4248(8) 0.1940(7) 0.7558(6) 0.0138(7) Uani 1 1 d . . . C2 C 0.6165(11) 0.1715(9) 0.8432(8) 0.0239(11) Uani 1 1 d . . . H2A H 0.5993 0.0526 0.7777 0.080 Uiso 1 1 calc R . . H2B H 0.6260 0.1676 0.9529 0.080 Uiso 1 1 calc R . . H2C H 0.7431 0.2802 0.8531 0.080 Uiso 1 1 calc R . . C3 C 0.2278(10) 0.0406(8) 0.7664(9) 0.0244(10) Uani 1 1 d . . . H3A H 0.1987 -0.0876 0.7101 0.080 Uiso 1 1 calc R . . H3B H 0.1095 0.0561 0.7136 0.080 Uiso 1 1 calc R . . H3C H 0.2522 0.0572 0.8820 0.080 Uiso 1 1 calc R . . C4 C 0.3890(11) 0.1632(10) 0.5706(7) 0.0244(11) Uani 1 1 d . . . H4A H 0.3414 0.0292 0.5133 0.080 Uiso 1 1 calc R . . H4B H 0.5189 0.2454 0.5642 0.080 Uiso 1 1 calc R . . H4C H 0.2844 0.1957 0.5188 0.080 Uiso 1 1 calc R . . loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_23 _atom_site_aniso_U_13 _atom_site_aniso_U_12 I1 0.01577(17) 0.02062(18) 0.01946(18) 0.00859(13) 0.01074(13) 0.00396(13) I2 0.01768(17) 0.02629(19) 0.01110(16) 0.00392(12) -0.00129(12) 0.01576(14) Si1 0.0081(5) 0.0121(5) 0.0063(5) 0.0032(4) 0.0007(4) 0.0049(4) C1 0.0140(17) 0.0171(18) 0.0102(17) 0.0029(14) 0.0035(14) 0.0092(15) C2 0.030(3) 0.027(3) 0.020(2) 0.007(2) 0.007(2) 0.021(2) C3 0.024(2) 0.016(2) 0.028(3) 0.0048(19) 0.010(2) 0.0074(19) C4 0.030(3) 0.032(3) 0.015(2) 0.005(2) 0.008(2) 0.022(2) _geom_special_details ; All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. ; loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_distance _geom_bond_site_symmetry_2 _geom_bond_publ_flag I1 Si1 2.4610(17) . ? I2 Si1 2.4681(15) . ? Si1 C1 1.904(5) . ? Si1 Si1 2.366(3) 2_667 ? C1 C3 1.536(8) . ? C1 C4 1.538(8) . ? C1 C2 1.546(8) . ? loop_ _geom_angle_atom_site_label_1 _geom_angle_atom_site_label_2 _geom_angle_atom_site_label_3 _geom_angle _geom_angle_site_symmetry_1 _geom_angle_site_symmetry_3 _geom_angle_publ_flag C1 Si1 Si1 120.00(17) . 2_667 ? C1 Si1 I1 108.55(16) . . ? Si1 Si1 I1 106.67(9) 2_667 . ? C1 Si1 I2 107.63(16) . . ? Si1 Si1 I2 105.38(8) 2_667 . ? I1 Si1 I2 108.12(6) . . ? C3 C1 C4 109.6(5) . . ? C3 C1 C2 109.6(5) . . ? C4 C1 C2 108.5(4) . . ? C3 C1 Si1 109.9(3) . . ? C4 C1 Si1 108.8(4) . . ? C2 C1 Si1 110.5(4) . . ? _diffrn_measured_fraction_theta_max 0.993 _diffrn_reflns_theta_full 34.97 _diffrn_measured_fraction_theta_full 0.993 _refine_diff_density_max 4.772 _refine_diff_density_min -6.575 _refine_diff_density_rms 0.600