The reaction of tertiary phosphines with (Ph2Se2I2)2‒the influence of steric and electronic effects.
Barnes, Nicholas A.; Godfrey, Stephen M.; Halton, Ruth T. A.; Mushtaq, Imrana; Pritchard, Robin G.; Dalton transactions (Cambridge, England : 2003)  (2006) 4795–4804; doi:10.1039/b608453b

data_7007674
_publ_section_title
;
 The reaction of tertiary phosphines with (Ph2Se2I2)2--the influence of
 steric and electronic effects.
;
_journal_issue                   40
_journal_name_full
'Dalton transactions (Cambridge, England : 2003)'
_journal_page_first              4795
_journal_page_last               4804
_journal_paper_doi               10.1039/b608453b
_journal_year                    2006
_chemical_formula_moiety         'C19.75 H19.50 Cl1.50 I P Se'
_chemical_formula_sum            'C19.75 H19.5 Cl1.5 I P Se'
_chemical_formula_weight         546.86
_chemical_name_systematic
;
?
;
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 116.58(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            8
_cell_length_a                   21.908(3)
_cell_length_b                   10.4978(10)
_cell_length_c                   20.798(2)
_cell_measurement_reflns_used    25
_cell_measurement_temperature    203(2)
_cell_measurement_theta_max      17.9
_cell_measurement_theta_min      10.4
_cell_volume                     4277.7(11)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      203(2)
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.997
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0201
_diffrn_reflns_av_sigmaI/netI    0.0515
_diffrn_reflns_limit_h_max       23
_diffrn_reflns_limit_h_min       -26
_diffrn_reflns_limit_k_max       0
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       24
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            7751
_diffrn_reflns_theta_full        25.00
_diffrn_reflns_theta_max         25.00
_diffrn_reflns_theta_min         1.96
_exptl_absorpt_coefficient_mu    3.461
_exptl_absorpt_correction_T_max  0.5444
_exptl_absorpt_correction_T_min  0.4233
_exptl_absorpt_correction_type   psi-scan
_exptl_absorpt_process_details
;
North A.C.T., Phillips D.C. & Mathews F.S. (1968) Acta. Cryst. A24, 351
Number of psi-scan sets used was 4
Theta correction was applied.
Averaged transmission function was used.
No Fourier smoothing was applied.
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.698
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       needle
_exptl_crystal_F_000             2124
_exptl_crystal_size_max          0.30
_exptl_crystal_size_mid          0.20
_exptl_crystal_size_min          0.20
_refine_diff_density_max         1.730
_refine_diff_density_min         -1.695
_refine_diff_density_rms         0.139
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.988
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     440
_refine_ls_number_reflns         7517
_refine_ls_number_restraints     4
_refine_ls_restrained_S_all      0.990
_refine_ls_R_factor_all          0.0876
_refine_ls_R_factor_gt           0.0515
_refine_ls_shift/su_max          0.046
_refine_ls_shift/su_mean         0.001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1000P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1321
_refine_ls_wR_factor_ref         0.1539
_reflns_number_gt                5263
_reflns_number_total             7517
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            b608453b.txt
_cod_data_source_block           t
_cod_original_cell_volume        4277.8(8)
_cod_original_sg_symbol_H-M      'P 21/c'
_cod_original_formula_sum        'C19.75 H19.50 Cl1.50 I P Se'
_cod_database_code               7007674