Closely related yet different: a borylene and its dimer are non-interconvertible but connected through reactivity.
Auerhammer, Dominic; Arrowsmith, Merle; Dewhurst, Rian D.; Kupfer, Thomas; Böhnke, Julian; Braunschweig, Holger; Chemical science 9 (2018) 2252–2260; doi:10.1039/c7sc04789d

data_1548594
_publ_section_title
;
 Closely related yet different: a borylene and its dimer are
 non-interconvertible but connected through reactivity.
;
_journal_issue                   8
_journal_name_full               'Chemical science'
_journal_page_first              2252
_journal_page_last               2260
_journal_paper_doi               10.1039/c7sc04789d
_journal_volume                  9
_journal_year                    2018
_chemical_formula_moiety         'C23 H37 B N2 Se2'
_chemical_formula_sum            'C23 H37 B N2 Se2'
_chemical_formula_weight         510.27
_chemical_properties_physical    Air-sensitive,Moisture-sensitive
_space_group_crystal_system      monoclinic
_space_group_IT_number           14
_space_group_name_Hall           '-P 2ybc'
_space_group_name_H-M_alt        'P 1 21/c 1'
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 1'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2014/7
_audit_update_record
;
2017-10-27 deposited with the CCDC.
2018-01-04 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 93.183(8)
_cell_angle_gamma                90
_cell_formula_units_Z            8
_cell_length_a                   17.551(6)
_cell_length_b                   15.552(5)
_cell_length_c                   17.729(6)
_cell_measurement_reflns_used    4204
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      22.21
_cell_measurement_theta_min      2.32
_cell_volume                     4832(3)
_computing_cell_refinement       'Saint+ ver. 7.68A (Bruker AXS)'
_computing_data_collection       'APEX2 ver. 2014.9 (Bruker AXS)'
_computing_data_reduction        'Saint+ ver. 7.68A (Bruker AXS)'
_computing_molecular_graphics    'ShelXLe (Huebschle et all, 2011)'
_computing_publication_material  'SHELXL-2014/6 (Sheldrick, 2014) '
_computing_structure_refinement  'SHELXL-2014/7 (Sheldrick, 2014)'
_computing_structure_solution    'SHELXT 2014/4 (Sheldrick, 2014)'
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device_type  'Bruker X8-APEX II'
_diffrn_measurement_method       '\f and \w scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.1589
_diffrn_reflns_av_unetI/netI     0.2229
_diffrn_reflns_Laue_measured_fraction_full 0.998
_diffrn_reflns_Laue_measured_fraction_max 0.998
_diffrn_reflns_limit_h_max       21
_diffrn_reflns_limit_h_min       -19
_diffrn_reflns_limit_k_max       19
_diffrn_reflns_limit_k_min       -17
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_limit_l_min       -22
_diffrn_reflns_number            32869
_diffrn_reflns_point_group_measured_fraction_full 0.998
_diffrn_reflns_point_group_measured_fraction_max 0.998
_diffrn_reflns_theta_full        26.000
_diffrn_reflns_theta_max         26.370
_diffrn_reflns_theta_min         2.130
_diffrn_source
'rotating-anode X-ray tube or sealed X-ray tube'
_exptl_absorpt_coefficient_mu    3.072
_exptl_absorpt_correction_T_max  0.7454
_exptl_absorpt_correction_T_min  0.5286
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'Sadabs 2014/4 (Bruker 2014)'
_exptl_crystal_colour            yellow
_exptl_crystal_density_diffrn    1.403
_exptl_crystal_description       block
_exptl_crystal_F_000             2096
_exptl_crystal_size_max          0.419
_exptl_crystal_size_mid          0.318
_exptl_crystal_size_min          0.273
_refine_diff_density_max         0.687
_refine_diff_density_min         -0.688
_refine_diff_density_rms         0.120
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.970
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     633
_refine_ls_number_reflns         9859
_refine_ls_number_restraints     210
_refine_ls_restrained_S_all      0.991
_refine_ls_R_factor_all          0.2188
_refine_ls_R_factor_gt           0.0694
_refine_ls_shift/su_max          0.020
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.1010P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1626
_refine_ls_wR_factor_ref         0.2245
_reflns_Friedel_coverage         0.000
_reflns_number_gt                4022
_reflns_number_total             9859
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c7sc04789d2.cif
_cod_data_source_block           6runs_a
_cod_depositor_comments
'Adding full bibliography for 1548594--1548603.cif.'
_cod_database_code               1548594
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_min   0.359
_shelx_estimated_absorpt_t_max   0.488
_exptl_absorpt_special_details
;The crystal was immersed in a film of perfluoropolyether oil, 
mounted on a a glass fiber and transferred to stream of cold nitrogen.
;
_shelx_res_checksum              44345