An unexpected valence bond isomerization to the heteroaromatic ring system: [1,2,3]triazolo[4,5-d]pyridazine
Kövér, Péter; Hajós, György; Riedl, Zsuzsanna; Párkányi, László; Kollenz, Gert; Chemical Communications  (2000) 1785–; doi:10.1039/b004775i

data_7111032
_publ_section_title
;
 An unexpected valence bond isomerization to the heteroaromatic ring
 system: [1,2,3]triazolo[4,5-d]pyridazine
;
_journal_issue                   18
_journal_name_full               'Chemical Communications'
_journal_page_first              1785
_journal_paper_doi               10.1039/b004775i
_journal_year                    2000
_chemical_formula_sum            'C22 H16 N8 O2'
_chemical_formula_weight         424.43
_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                 92.00(1)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   6.163(1)
_cell_length_b                   17.243(4)
_cell_length_c                   18.471(1)
_cell_measurement_reflns_used    25
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      12.62
_cell_measurement_theta_min      9.94
_cell_volume                     1961.7(6)
_computing_cell_refinement       'CAD4 Express'
_computing_data_collection       'CAD4 Express'
_computing_data_reduction        'XCAD4 (Harms 1996)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.988
_diffrn_measured_fraction_theta_max 0.988
_diffrn_measurement_device_type  'Enraf-Nonius CAD4'
_diffrn_measurement_method       \w--2\q
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           'MO k\a'
_diffrn_radiation_wavelength     0.710730
_diffrn_reflns_av_R_equivalents  0.0206
_diffrn_reflns_av_sigmaI/netI    0.0814
_diffrn_reflns_limit_h_max       7
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       6
_diffrn_reflns_limit_k_min       -21
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_limit_l_min       -22
_diffrn_reflns_number            4175
_diffrn_reflns_theta_full        25.74
_diffrn_reflns_theta_max         25.74
_diffrn_reflns_theta_min         2.21
_diffrn_standards_decay_%        1
_diffrn_standards_interval_time  60
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    0.099
_exptl_absorpt_correction_T_max  0.9882
_exptl_absorpt_correction_T_min  0.9707
_exptl_absorpt_correction_type   psi-scan
_exptl_crystal_colour            orange
_exptl_crystal_density_diffrn    1.437
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       needle
_exptl_crystal_F_000             880
_exptl_crystal_size_max          0.40
_exptl_crystal_size_mid          0.14
_exptl_crystal_size_min          0.12
_refine_diff_density_max         0.158
_refine_diff_density_min         -0.158
_refine_diff_density_rms         0.037
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.842
_refine_ls_hydrogen_treatment    riding
_refine_ls_matrix_type           full
_refine_ls_number_parameters     290
_refine_ls_number_reflns         3713
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.842
_refine_ls_R_factor_all          0.1173
_refine_ls_R_factor_gt           0.0404
_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^)+(0.0559P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0909
_refine_ls_wR_factor_ref         0.1036
_reflns_number_gt                1842
_reflns_number_total             3713
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            b004775isup1.cif
_cod_data_source_block           kp56
_cod_original_sg_symbol_H-M      P21/c
_cod_database_code               7111032