Amidines: a deeper look at the archetypal pro-ligand.
de Vere-Tucker, Matthew; Squire, Imogen; Tritto, Michelangelo; Anandkar, Rohil; Syeda, Tayyibah; Uthayan, Divia; Aguila, Gabrielle; Silva de Moraes, Lygia; Bakewell, Clare; Dalton transactions (Cambridge, England : 2003) 55 (2026) 4977–4987; doi:10.1039/d6dt00276e

data_7720572
_publ_section_title
;
 Amidines: a deeper look at the archetypal pro-ligand.
;
_journal_issue                   12
_journal_name_full
'Dalton transactions (Cambridge, England : 2003)'
_journal_page_first              4977
_journal_page_last               4987
_journal_paper_doi               10.1039/d6dt00276e
_journal_volume                  55
_journal_year                    2026
_chemical_formula_moiety         'C56 H67 Al N4, 1[C6H6]'
_chemical_formula_sum            'C62 H73 Al N4'
_chemical_formula_weight         901.22
_chemical_properties_physical    Air-sensitive,Moisture-sensitive
_space_group_crystal_system      monoclinic
_space_group_IT_number           15
_space_group_name_Hall           '-C 2yc'
_space_group_name_H-M_alt        'C 1 2/c 1'
_atom_sites_solution_hydrogens   mixed
_audit_creation_date             2026-01-28
_audit_creation_method
;
Olex2 1.5
(compiled 2025.07.13 svn.rb7424aed for OlexSys, GUI svn.r7314)
;
_audit_update_record
;
2026-01-30 deposited with the CCDC.	2026-03-03 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 102.843(2)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   22.1834(5)
_cell_length_b                   9.6461(2)
_cell_length_c                   25.8423(6)
_cell_measurement_reflns_used    16533
_cell_measurement_temperature    150.00(10)
_cell_measurement_theta_max      71.2240
_cell_measurement_theta_min      3.5230
_cell_volume                     5391.5(2)
_computing_cell_refinement       'CrysAlisPro 1.171.43.119a (Rigaku OD, 2024)'
_computing_data_collection
'CrysAlisPro system (CCD 43.119a 64-bit (release 08-04-2024))'
_computing_data_reduction        'CrysAlisPro 1.171.43.119a (Rigaku OD, 2024)'
_computing_molecular_graphics    'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_structure_refinement  'SHELXL 2019/3 (Sheldrick, 2015)'
_computing_structure_solution    'SHELXT 2018/2 (Sheldrick, 2018)'
_diffrn_ambient_environment      N~2~
_diffrn_ambient_temperature      150.00(10)
_diffrn_detector                 'Hybrid Pixel Array Detector'
_diffrn_detector_area_resol_mean 10.0000
_diffrn_detector_type            'HyPix-Arc 100'
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 0.977
_diffrn_measurement_details
;
List of Runs (angles in degrees, time in seconds):

  # Type    Start    End  Width  t~exp~   \w     \q     \k     \f   Frames
  1  \w    -16.00  25.00   0.50    2.00    --   50.01 -43.00   8.00   82
  2  \w     82.00 122.00   0.50    2.00    --   50.01  43.00 160.00   80
  3  \w     27.00  58.00   0.50    2.00    --   50.01 -43.00   8.00   62
  4  \w     76.00 103.00   0.50    2.00    --  102.76 -43.00   8.00   54
  5  \w    -40.00 -15.00   0.50    2.00    --    2.00 125.00  90.99   50
  6  \w    -32.00  -5.00   0.50    2.00    --    6.00 118.00-173.79   54
  7  \w    -39.00 -14.00   0.50    2.00    --   10.00 130.00   9.96   50
  8  \w    -51.00 -26.00   0.50    2.00    --   14.00 152.00 -31.97   50
  9  \w    -12.00  13.00   0.50    2.00    --   22.00 102.00  65.15   50
 10  \w      6.00  33.00   0.50    2.00    --   34.00  95.00 -59.98   54
 11  \w     14.00  44.00   0.50    2.00    --   38.00  90.00-141.55   60
 12  \w     15.00  41.00   0.50    2.00    --   42.00  90.00 135.53   52
 13  \w     20.00  45.00   0.50    2.00    --   46.00  88.00 -63.23   50
 14  \w     25.00  51.00   0.50    2.00    --   46.00  81.00  64.85   52
 15  \w     85.00 110.00   0.50    2.00    --   50.00  82.00-125.64   50
 16  \w     29.00  58.00   0.50    2.00    --   50.00  82.00-125.64   58
 17  \w     31.00  57.00   0.50    2.00    --   50.01 -38.00  90.00   52
 18  \w     56.00  90.00   0.50    2.00    --   50.01-125.00  90.00   68
 19  \w     -1.00  70.00   0.50    2.00    --   50.01 -77.00 -90.00  142
 20  \w      9.00  62.00   0.50    2.00    --   50.01 -57.00 -90.00  106
 21  \w    -21.00   6.00   0.50    2.00    --   50.01 -38.00  90.00   54
 22  \w     77.00 103.00   0.50    2.00    --   54.00  82.00  -5.19   52
 23  \w     32.00  59.00   0.50    2.00    --   54.00  82.00  -5.19   54
 24  \w     32.00  59.00   0.50    2.00    --   54.00  83.00 168.70   54
 25  \w     33.00  59.00   0.50    2.00    --   54.00  79.00 -40.27   52
 26  \w     89.00 114.00   0.50    2.00    --   54.00  83.00 120.02   50
 27  \w     32.00  62.00   0.50    2.00    --   54.00  83.00 120.02   60
 28  \w     36.00  63.00   0.50    2.00    --   58.00  82.00-167.24   54
 29  \w     35.00  61.00   0.50    2.00    --   58.00  83.00 -88.82   52
 30  \w     39.00  92.00   0.50    2.00    --   62.00  83.00  74.21  106
 31  \w     43.00  69.00   0.50    2.00    --   66.00  83.00 144.10   52
 32  \w     90.00 126.00   0.50    2.00    --   66.00  73.00  26.29   72
 33  \w     45.00  87.00   0.50    2.00    --   66.00  82.00 109.70   84
 34  \w     92.00 126.00   0.50    2.00    --   66.00  82.00  -6.38   68
 35  \w     48.00  76.00   0.50    2.00    --   66.00  82.00  -6.38   56
 36  \w     90.00 125.00   0.50    2.00    --   66.00  82.00 -94.03   70
 37  \w     44.00  71.00   0.50    2.00    --   66.00  82.00 -94.03   54
 38  \w     45.00 126.00   0.50    2.00    --   66.00  82.00 -32.55  162
 39  \w     50.00  80.00   0.50    2.00    --   66.00  73.00  26.29   60
 40  \w    100.00 126.00   0.50    2.00    --   66.00  82.00  39.94   52
 41  \w     44.00  70.00   0.50    2.00    --   66.00  82.00  39.94   52
 42  \w     94.00 126.00   0.50    2.00    --   70.00  83.00-163.48   64
 43  \w     47.00  90.00   0.50    2.00    --   70.00  83.00-163.48   86
 44  \w    105.00 130.00   0.50    2.00    --   70.00  82.00 -58.27   50
 45  \w     50.00  90.00   0.50    2.00    --   70.00  82.00 -58.27   80
 46  \w     94.00 130.00   0.50    2.00    --   70.00  82.00-142.42   72
 47  \w     47.00  83.00   0.50    2.00    --   70.00  83.00 -78.22   72
 48  \w     49.00 130.00   0.50    2.00    --   70.00  82.00 153.90  162
 49  \w     48.00  88.00   0.50    2.00    --   70.00  82.00-142.42   80
 50  \w    106.00 134.00   0.50    2.00    --   74.00  82.00  67.53   56
 51  \w     52.00  85.00   0.50    2.00    --   74.00  82.00  67.53   66
 52  \w     76.00 138.00   0.50    2.00    --   74.00  75.00  80.41  124
 53  \w     93.00 147.00   0.50    2.00    --  102.76  57.00   0.00  108
 54  \w     41.00 105.00   0.50    2.00    --  102.76 -99.00  60.00  128
 55  \w     83.00 118.00   0.50    2.00    --  102.76  77.00 -90.00   70
 56  \w    124.00 165.00   0.50    2.00    --  102.76  77.00 120.00   82
 57  \w     83.00 121.00   0.50    2.00    --  102.76  77.00 120.00   76
 58  \w    137.00 164.00   0.50    2.00    --  102.76  77.00-180.00   54
 59  \w     83.00 125.00   0.50    2.00    --  102.76  77.00-180.00   84
 60  \w     84.00 164.00   0.50    2.00    --  102.76  77.00  60.00  160
 61  \w     85.00 165.00   0.50    2.00    --  102.76  77.00   0.00  160
 62  \w     83.00 160.00   0.50    2.00    --  102.76  77.00  90.00  154
 63  \w    133.00 159.00   0.50    2.00    --  102.76  77.00 -30.00   52
 64  \w    106.00 133.00   0.50    2.00    --  102.76  43.00 160.00   54
 65  \w     50.00 110.00   0.50    2.00    --  102.76 -99.00 -60.00  120
 66  \w     90.00 163.00   0.50    2.00    --  102.76  77.00  30.00  146
 67  \w     83.00 109.00   0.50    2.00    --  102.76  77.00 -30.00   52
 68  \w     93.00 139.00   0.50    2.00    --  102.76  57.00 -90.00   92
 69  \w    130.00 159.00   0.50    2.00    --  102.76  77.00 150.00   58
 70  \w     83.00 108.00   0.50    2.00    --  102.76  77.00 150.00   50
 71  \w    128.00 165.00   0.50    2.00    --  102.76  77.00-150.00   74
 72  \w     91.00 118.00   0.50    2.00    --  102.76  57.00 -30.00   54
 73  \w    126.00 162.00   0.50    2.00    --  102.76  57.00 -60.00   72
 74  \w     83.00 109.00   0.50    2.00    --  102.76  77.00-150.00   52
 75  \w     43.00 105.00   0.50    2.00    --  102.76 -99.00-150.00  124
 76  \w     93.00 122.00   0.50    2.00    --  102.76  57.00 -60.00   58
 77  \w    100.00 127.00   0.50    2.00    --  102.76  57.00  30.00   54
 78  \w    139.00 166.00   0.50    2.00    --  102.76  57.00-180.00   54
 79  \w    128.00 164.00   0.50    2.00    --  102.76  77.00-120.00   72
 80  \w     95.00 126.00   0.50    2.00    --  102.76  57.00-180.00   62
 81  \w     93.00 121.00   0.50    2.00    --  102.76  57.00-120.00   56
 82  \w     84.00 110.00   0.50    2.00    --  102.76  77.00-120.00   52
 83  \w    138.00 163.00   0.50    2.00    --  102.76  77.00 -60.00   50
 84  \w     84.00 124.00   0.50    2.00    --  102.76  77.00 -60.00   80
 85  \w    107.00 162.00   0.50    2.00    --  102.76 125.00 -90.00  110
 86  \w     43.00 111.00   0.50    2.00    --  107.92 -49.00 125.08  136
 87  \w     35.00 111.00   0.50    2.00    --  107.92 -38.00 -91.62  152
 88  \w     50.00 104.00   0.50    2.00    --  107.92 -95.00 134.86  108
 89  \w     44.00  87.00   0.50    2.00    --  107.92 -42.00  70.32   86
 90  \w     48.00 107.00   0.50    2.00    --  107.92 -96.00  -6.73  118
 91  \w     37.00 112.00   0.50    2.00    --  107.92 -51.00  -0.44  150
 92  \w     43.00 109.00   0.50    2.00    --  107.92 -39.00-166.72  132
 93  \w     56.00 107.00   0.50    2.00    --  107.92 -97.00-141.90  102
;
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type
'SuperNova, Dual, Cu at home/near, HyPix-Arc 100'
_diffrn_measurement_method       '\w scans'
_diffrn_orient_matrix_type
'CrysAlisPro convention (1999,Acta A55,543-557)'
_diffrn_orient_matrix_UB_11      0.0683551000
_diffrn_orient_matrix_UB_12      0.0302975000
_diffrn_orient_matrix_UB_13      0.0006928000
_diffrn_orient_matrix_UB_21      -0.0191939000
_diffrn_orient_matrix_UB_22      0.1324556000
_diffrn_orient_matrix_UB_23      -0.0328099000
_diffrn_orient_matrix_UB_31      0.0055881000
_diffrn_orient_matrix_UB_32      0.0839128000
_diffrn_orient_matrix_UB_33      0.0515954000
_diffrn_radiation_monochromator  mirror
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           'Cu K\a'
_diffrn_radiation_wavelength     1.54184
_diffrn_reflns_av_R_equivalents  0.0894
_diffrn_reflns_av_unetI/netI     0.0349
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 0.977
_diffrn_reflns_limit_h_max       27
_diffrn_reflns_limit_h_min       -27
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       32
_diffrn_reflns_limit_l_min       -31
_diffrn_reflns_number            64603
_diffrn_reflns_point_group_measured_fraction_full 1.000
_diffrn_reflns_point_group_measured_fraction_max 0.977
_diffrn_reflns_theta_full        67.684
_diffrn_reflns_theta_max         78.895
_diffrn_reflns_theta_min         3.508
_diffrn_source                   'micro-focus sealed X-ray tube'
_diffrn_source_type              'SuperNova (Cu) X-ray Source'
_exptl_absorpt_coefficient_mu    0.633
_exptl_absorpt_correction_T_max  1.000
_exptl_absorpt_correction_T_min  0.452
_exptl_absorpt_correction_type   gaussian
_exptl_absorpt_process_details
;
CrysAlisPro 1.171.43.119a (Rigaku Oxford Diffraction, 2024)
Numerical absorption correction based on gaussian integration over
a multifaceted crystal model
Empirical absorption correction using spherical harmonics,
implemented in SCALE3 ABSPACK scaling algorithm.
;
_exptl_crystal_colour            'clear colourless'
_exptl_crystal_colour_lustre     clear
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    1.110
_exptl_crystal_description       block
_exptl_crystal_F_000             1944
_exptl_crystal_recrystallization_method
'Re-crystallisation from solvent: benzene'
_exptl_crystal_size_max          0.391
_exptl_crystal_size_mid          0.307
_exptl_crystal_size_min          0.206
_refine_diff_density_max         0.366
_refine_diff_density_min         -0.257
_refine_diff_density_rms         0.044
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.044
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     289
_refine_ls_number_reflns         5700
_refine_ls_number_restraints     3
_refine_ls_restrained_S_all      1.046
_refine_ls_R_factor_all          0.0685
_refine_ls_R_factor_gt           0.0559
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0900P)^2^+2.8328P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1557
_refine_ls_wR_factor_ref         0.1645
_reflns_Friedel_coverage         0.000
_reflns_number_gt                4495
_reflns_number_total             5700
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d6dt00276e3.cif
_cod_data_source_block           (depAmpTol)2AlH_16-Al''
_cod_depositor_comments
'Adding full bibliography for 7720566--7720581.cif.'
_cod_database_code               7720572
_shelx_shelxl_version_number     2019/3
_chemical_oxdiff_formula         'C56 H67 Al N4'
_chemical_oxdiff_usercomment     'IS196 TS019b'
_shelx_estimated_absorpt_t_max   0.881
_shelx_estimated_absorpt_t_min   0.790
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All C(H,H) groups
 At 1.5 times of:
  All C(H,H,H) groups, All Al(H) groups
2. Restrained distances
 N1-Al2 \\sim N1-Al1
 with sigma of 0.02
 N2-Al2 \\sim N2-Al1
 with sigma of 0.02
 Al1-HA \\sim Al2-H
 with sigma of 0.02
3. Others
 Sof(Al1)=Sof(HA)=0.5*(1-FVAR(2))
 Sof(Al2)=Sof(H)=0.5*FVAR(2)
4.a Secondary CH2 refined with riding coordinates:
 C16(H16A,H16B), C27(H27A,H27B), C14(H14A,H14B), C25(H25A,H25B)
4.b Aromatic/amide H refined with riding coordinates:
 C3(H3), C7(H7), C12(H12), C6(H6), C4(H4), C10(H10), C23(H23), C11(H11),
 C22(H22), C21(H21)
4.c Idealised Me refined as rotating group:
 C28(H28A,H28B,H28C), C8(H8A,H8B,H8C), C18(H18A,H18B,H18C), C26(H26A,H26B,
 H26C), C15(H15A,H15B,H15C)
;
_smtbx_masks_special_details
;
A solvent mask was calculated and 200 electrons were 
found in a volume of 952\%A^3^ in 1 void per unit cell. 
This is consistent with the presence of 
1[C6H6] per Asymmetric Unit 
which account for 168 electrons 
per unit cell.
;
_smtbx_masks_void_probe_radius   1.2
_smtbx_masks_void_truncation_radius 1.2
_shelx_res_checksum              40055
_shelx_hkl_checksum              70290
_shelx_fab_checksum              47510
_olex2_submission_special_instructions 'No special instructions were received'
_oxdiff_exptl_absorpt_empirical_details
;
Empirical correction (ABSPACK) includes:
- Absorption correction using spherical harmonics
- Frame scaling
;
_oxdiff_exptl_absorpt_empirical_full_max 4.941
_oxdiff_exptl_absorpt_empirical_full_min 0.605