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###           Electronic papers (Acta Crystallographica Section C)         ###
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# This paper is published electronically. It meets the data-validation       #
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# available by email and via the online contents pages for that issue.       #
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data_I
_audit_creation_method     SHELXL-97
_chemical_name_systematic     'Tetrakis(imidazole-N³)nickel(II) diacetate'
_chemical_name_common     ?
_chemical_formula_moiety     'C16 H22 N8 Ni O4'
_chemical_formula_sum     'C16 H22 N8 Ni O4'
_chemical_formula_structural     '[Ni (C3 H4 N2)4 (C2 H3 O2)2]'
_chemical_formula_iupac     '[Ni (C2 H3 O2)2 (C3 H4 N2)4]'
_chemical_formula_weight     449.13
_chemical_melting_point     ?
_symmetry_cell_setting     Monoclinic
_symmetry_space_group_name_H-M     'C 2/c'
loop_
    _symmetry_equiv_pos_as_xyz
    'x, y, z'
    'x, -y, z+1/2'
    'x+1/2, y+1/2, z'
    'x+1/2, -y+1/2, z+1/2'
    '-x, -y, -z'
    '-x, y, -z-1/2'
    '-x+1/2, -y+1/2, -z'
    '-x+1/2, y+1/2, -z-1/2'
_cell_length_a     13.46(2)
_cell_length_b     8.620(10)
_cell_length_c     17.89(2)
_cell_angle_alpha     90.00
_cell_angle_beta     105.280(10)
_cell_angle_gamma     90.00
_cell_volume     2001(4)
_cell_formula_units_Z     4
_cell_measurement_reflns_used     3146
_cell_measurement_theta_min     2.36
_cell_measurement_theta_max     26.00
_cell_measurement_temperature     298(2)
_exptl_crystal_description     Parallelepiped
_exptl_crystal_colour     'pale blue'
_exptl_crystal_size_max      .25
_exptl_crystal_size_mid      .25
_exptl_crystal_size_min      .20
_exptl_crystal_density_diffrn     1.491
_exptl_crystal_density_meas     ?
_exptl_crystal_density_method     'not measured'
_exptl_crystal_F_000     936
_exptl_absorpt_coefficient_mu     1.010
_exptl_absorpt_correction_type     none
_exptl_absorpt_process_details     ?
_exptl_absorpt_correction_T_min     ?
_exptl_absorpt_correction_T_max     ?
_diffrn_ambient_temperature     298(2)
_diffrn_radiation_type     MoK\a
_diffrn_radiation_wavelength      .71073
_diffrn_radiation_source     'fine-focus sealed tube'
_diffrn_radiation_monochromator     graphite
_diffrn_measurement_device_type     'MarResearch Image Plate'
_diffrn_measurement_method
                              '95 frames at 2° intervals, counting time 2 min.'
_diffrn_detector_area_resol_mean     ?
_diffrn_reflns_number     3146
_diffrn_reflns_av_R_equivalents      .027
_diffrn_reflns_av_sigmaI/netI      .031
_diffrn_reflns_theta_min     2.36
_diffrn_reflns_theta_max     26.00
_diffrn_reflns_theta_full     26.00
_diffrn_measured_fraction_theta_max      .937
_diffrn_measured_fraction_theta_full      .937
_diffrn_reflns_limit_h_min     0
_diffrn_reflns_limit_h_max     16
_diffrn_reflns_limit_k_min     -10
_diffrn_reflns_limit_k_max     10
_diffrn_reflns_limit_l_min     -21
_diffrn_reflns_limit_l_max     21
_diffrn_standards_number     ?
_diffrn_standards_interval_count     ?
_diffrn_standards_interval_time     ?
_diffrn_standards_decay_%     0
_reflns_number_total     1842
_reflns_number_gt     1540
_reflns_threshold_expression     I>2σ(I)
_refine_ls_structure_factor_coef     Fsqd
_refine_ls_matrix_type     full
_refine_ls_R_factor_all      .047
_refine_ls_R_factor_gt      .036
_refine_ls_wR_factor_ref      .105
_refine_ls_goodness_of_fit_ref     1.063
_refine_ls_restrained_S_all     1.063
_refine_ls_number_reflns     1842
_refine_ls_number_parameters     135
_refine_ls_number_restraints     0
_refine_ls_hydrogen_treatment     constr
_refine_ls_weighting_scheme     calc
_refine_ls_weighting_details
     'calc w = 1/[σ²(Fo²)+(0.0629P)²+1.9165P] where P = (Fo²+2Fc²)/3'
_refine_ls_shift/su_max     <0.001
_refine_ls_shift/su_mean      .000
_refine_diff_density_max      .52
_refine_diff_density_min      -.34
_refine_ls_extinction_method     SHELXL97
_refine_ls_extinction_coef      .0090(10)
loop_
    _atom_type_symbol
    _atom_type_description
    _atom_type_scat_dispersion_real
    _atom_type_scat_dispersion_imag
    _atom_type_scat_source
    'C' 'C'  .0033  .0016
                         'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
    'H' 'H'  .0000  .0000
                         'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
    'N' 'N'  .0061  .0033
                         'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
    'O' 'O'  .0106  .0060
                         'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
    'Ni' 'Ni'  .3393 1.1124
                         'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
_computing_data_collection     'XDS (Kabsch, 1988)'
_computing_cell_refinement     'XDS'
_computing_data_reduction     'XDS'
_computing_structure_solution     'SHELXS97 (Sheldrick, 1997)'
_computing_structure_refinement     'SHELXL97 (Sheldrick, 1997)'
_computing_molecular_graphics     ?
_computing_publication_material     'SHELXL97'
loop_
    _atom_site_label
    _atom_site_fract_x
    _atom_site_fract_y
    _atom_site_fract_z
    _atom_site_U_iso_or_equiv
    _atom_site_adp_type
    _atom_site_calc_flag
    _atom_site_refinement_flags
    _atom_site_occupancy
    _atom_site_disorder_assembly
    _atom_site_disorder_group
    _atom_site_type_symbol
    Ni1  .0000  .0000  .5000  .0317(2) Uani d S 1 . . Ni
    O1  -.1956(2)  .0949(2)  .43890(10)
                                       .0444(5) Uani d . 1 . . O
    O2  -.2666(2)  .1044(2)  .31320(10)
                                       .0512(5) Uani d . 1 . . O
    N1  .0208(2)  .1550(2)  .58490(10)
                                      .0323(5) Uani d . 1 . . N
    N2  .0932(2)  .2931(3)  .68720(10)
                                      .0381(5) Uani d . 1 . . N
    N3  .0645(2)  .1525(3)  .43800(10)
                                      .0354(5) Uani d . 1 . . N
    N4  .1631(2)  .3388(3)  .41270(10)
                                      .0420(5) Uani d . 1 . . N
    C1  .1007(2)  .1668(3)  .64670(10)
                                      .0335(5) Uani d . 1 . . C
    C2  .0046(2)  .3669(3)  .6504(2)  .0452(7) Uani d . 1 . . C
    C3  -.0403(2)  .2817(3)  .58740(10)
                                       .0402(6) Uani d . 1 . . C
    C4  .1204(2)  .2773(3)  .4648(2)  .0383(6) Uani d . 1 . . C
    C5  .1328(2)  .2513(4)  .3476(2)  .0546(8) Uani d . 1 . . C
    C6  .0731(2)  .1372(4)  .3636(2)  .0525(8) Uani d . 1 . . C
    C7  -.2234(2)  .1686(3)  .37650(10)
                                       .0348(5) Uani d . 1 . . C
    C8  -.2038(3)  .3406(4)  .3775(2)  .0659(9) Uani d . 1 . . C
    H2  .1366  .3229  .7292  .046 Uiso calc R 1 . . H
    H4  .2025  .4189  .4190  .050 Uiso calc R 1 . . H
    H1  .1546  .0960  .6598  .040 Uiso calc R 1 . . H
    H2a  -.0203  .4589  .6658  .054 Uiso calc R 1 . . H
    H3  -.1024  .3047  .5516  .048 Uiso calc R 1 . . H
    H4a  .1287  .3171  .5144  .046 Uiso calc R 1 . . H
    H5  .1499  .2670  .3010  .066 Uiso calc R 1 . . H
    H6  .0422  .0595  .3292  .063 Uiso calc R 1 . . H
    H8a  -.2368  .3900  .4127  .099 Uiso calc R 1 . . H
    H8b  -.2310  .3820  .3263  .099 Uiso calc R 1 . . H
    H8c  -.1310  .3597  .3941  .099 Uiso calc R 1 . . H
loop_
    _atom_site_aniso_label
    _atom_site_aniso_U_11
    _atom_site_aniso_U_22
    _atom_site_aniso_U_33
    _atom_site_aniso_U_12
    _atom_site_aniso_U_13
    _atom_site_aniso_U_23
    Ni1  .0451(3)  .0280(3)  .0225(3)  -.0122(2)  .0097(2)  -.0057(2)
    O1  .0570(10)
                 .0400(10)
                          .0320(10)
                                   .0010(10)
                                            .0050(10)
                                                     .0060(10)
    O2  .0560(10)
                 .0460(10)
                          .0390(10)
                                   .0140(10)
                                            -.0090(10)
                                                      .0030(10)
    N1  .0340(10)
                 .0340(10)
                          .0280(10)
                                   -.0040(10)
                                             .0060(10)
                                                      -.0030(10)
    N2  .0380(10)
                 .0390(10)
                          .0320(10)
                                   .0010(10)
                                            -.0020(10)
                                                      -.0100(10)
    N3  .0370(10)
                 .0360(10)
                          .0310(10)
                                   -.0040(10)
                                             .0060(10)
                                                      .0020(10)
    N4  .0370(10)
                 .0370(10)
                          .0510(10)
                                   -.0030(10)
                                             .0110(10)
                                                      .0100(10)
    C1  .0340(10)
                 .0340(10)
                          .0300(10)
                                   .0020(10)
                                            .0050(10)
                                                     -.0050(10)
    C2  .048(2)  .046(2)  .0380(10)
                                   .0140(10)
                                            .0040(10)
                                                     -.0100(10)
    C3  .0330(10)
                 .048(2)  .0350(10)
                                   .0070(10)
                                            .0010(10)
                                                     -.0040(10)
    C4  .0390(10)
                 .0340(10)
                          .0410(10)
                                   -.0040(10)
                                             .0090(10)
                                                      .0040(10)
    C5  .062(2)  .060(2)  .046(2)  -.009(2)  .0210(10)
                                                      .012(2)
    C6  .065(2)  .057(2)  .037(2)  -.020(2)  .0180(10)
                                                      -.0030(10)
    C7  .0310(10)
                 .0350(10)
                          .0370(10)
                                   .0040(10)
                                            .0060(10)
                                                     .0030(10)
    C8  .083(3)  .038(2)  .067(2)  -.010(2)  .004(2)  .010(2)
loop_
    _geom_bond_atom_site_label_1
    _geom_bond_atom_site_label_2
    _geom_bond_site_symmetry_2
    _geom_bond_distance
    _geom_bond_publ_flag
    Ni1 N1 . 1.986(3) yes
    Ni1 N1 5_556 1.986(3) yes
    Ni1 N3 . 2.054(3) yes
    Ni1 N3 5_556 2.054(3) yes
    Ni1 O1 . 2.697(3) yes
    Ni1 O1 5_556 2.697(3) yes
    O1 C7 . 1.252(3) no
    O2 C7 . 1.257(3) no
    N1 C1 . 1.327(3) no
    N1 C3 . 1.375(4) no
    N2 C1 . 1.327(3) no
    N2 C2 . 1.359(4) no
    N3 C4 . 1.327(3) no
    N3 C6 . 1.372(4) no
    N4 C4 . 1.329(3) no
    N4 C5 . 1.356(4) no
    C2 C3 . 1.348(4) no
    C5 C6 . 1.347(4) no
    C7 C8 . 1.505(4) no
    N2 H2 .  .8600 no
    N4 H4 .  .8600 no
    C1 H1 .  .9300 no
    C2 H2a .  .9300 no
    C3 H3 .  .9300 no
    C4 H4a .  .9300 no
    C5 H5 .  .9300 no
    C6 H6 .  .9300 no
    C8 H8a .  .9600 no
    C8 H8b .  .9600 no
    C8 H8c .  .9600 no
loop_
    _geom_angle_atom_site_label_1
    _geom_angle_atom_site_label_2
    _geom_angle_atom_site_label_3
    _geom_angle_site_symmetry_1
    _geom_angle_site_symmetry_3
    _geom_angle
    _geom_angle_publ_flag
    N1 Ni1 N1 . 5_556 180.0 yes
    N1 Ni1 N3 . . 89.30(10)
                          yes
    N1 Ni1 N3 . 5_556 90.70(10)
                              yes
    N1 Ni1 O1 . . 91.80(10)
                          yes
    N1 Ni1 O1 . 5_556 88.20(10)
                              yes
    N1 Ni1 N3 5_556 . 90.70(10)
                              yes
    N1 Ni1 N3 5_556 5_556 89.30(10)
                                  yes
    N1 Ni1 O1 5_556 . 88.20(10)
                              yes
    N1 Ni1 O1 5_556 5_556 91.80(10)
                                  yes
    N3 Ni1 N3 . 5_556 180.0 yes
    N3 Ni1 O1 . . 95.40(10)
                          yes
    N3 Ni1 O1 . 5_556 84.60(10)
                              yes
    N3 Ni1 O1 5_556 . 84.60(10)
                              yes
    N3 Ni1 O1 5_556 5_556 95.40(10)
                                  yes
    O1 Ni1 O1 . 5_556 180.00(10)
                               yes
    C7 O1 Ni1 . . 123.0(2) no
    C1 N1 C3 . . 105.8(2) no
    C1 N1 Ni1 . . 127.5(2) no
    C3 N1 Ni1 . . 126.4(2) no
    C1 N2 C2 . . 107.6(2) no
    C4 N3 Ni1 . . 127.0(2) no
    C6 N3 Ni1 . . 128.2(2) no
    N2 C1 N1 . . 110.9(2) no
    C4 N3 C6 . . 104.1(2) no
    C4 N4 C5 . . 107.1(2) no
    C3 C2 N2 . . 107.1(2) no
    C2 C3 N1 . . 108.6(2) no
    N3 C4 N4 . . 112.1(2) no
    C6 C5 N4 . . 106.5(3) no
    C5 C6 N3 . . 110.1(3) no
    O1 C7 O2 . . 122.6(3) no
    O1 C7 C8 . . 118.6(3) no
    O2 C7 C8 . . 118.8(2) no
    C3 C2 H2a . . 126.5 no
    N2 C2 H2a . . 126.5 no
    C1 N2 H2 . . 126.2 no
    C2 N2 H2 . . 126.2 no
    C4 N4 H4 . . 126.4 no
    C5 N4 H4 . . 126.4 no
    N2 C1 H1 . . 124.5 no
    N1 C1 H1 . . 124.5 no
    C2 C3 H3 . . 125.7 no
    N1 C3 H3 . . 125.7 no
    N3 C4 H4a . . 123.9 no
    N4 C4 H4a . . 123.9 no
    C6 C5 H5 . . 126.8 no
    N4 C5 H5 . . 126.8 no
    C5 C6 H6 . . 124.9 no
    N3 C6 H6 . . 124.9 no
    C7 C8 H8a . . 109.5 no
    C7 C8 H8b . . 109.5 no
    H8a C8 H8b . . 109.5 no
    C7 C8 H8c . . 109.5 no
    H8a C8 H8c . . 109.5 no
    H8b C8 H8c . . 109.5 no
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_site_symmetry_1
    _geom_torsion_site_symmetry_2
    _geom_torsion_site_symmetry_3
    _geom_torsion_site_symmetry_4
    _geom_torsion
    _geom_torsion_publ_flag
    N1 Ni1 O1 C7 . . . . 108.9(2) no
    N1 Ni1 O1 C7 5_556 . . . -71.1(2) no
    N3 Ni1 O1 C7 5_556 . . . -160.6(2) no
    N3 Ni1 O1 C7 . . . . 19.4(2) no
    O1 Ni1 O1 C7 5_556 . . .  15E1(10)
                                      no
    N1 Ni1 N1 C1 5_556 . . .  -12E1(10)
                                       no
    N3 Ni1 N1 C1 5_556 . . . 86.9(2) no
    N3 Ni1 N1 C1 . . . . -93.1(2) no
    O1 Ni1 N1 C1 5_556 . . . -8.4(2) no
    O1 Ni1 N1 C1 . . . . 171.6(2) no
    N1 Ni1 N1 C3 5_556 . . .  5E1(10)
                                     no
    N3 Ni1 N1 C3 5_556 . . . -100.2(2) no
    N3 Ni1 N1 C3 . . . . 79.8(2) no
    O1 Ni1 N1 C3 5_556 . . . 164.5(2) no
    O1 Ni1 N1 C3 . . . . -15.5(2) no
    N1 Ni1 N3 C4 . . . . 16.1(2) no
    N1 Ni1 N3 C4 5_556 . . . -163.9(2) no
    N3 Ni1 N3 C4 5_556 . . .  17E1(10)
                                      no
    O1 Ni1 N3 C4 5_556 . . . -72.1(2) no
    O1 Ni1 N3 C4 . . . . 107.9(2) no
    N1 Ni1 N3 C6 . . . . -174.5(2) no
    N1 Ni1 N3 C6 5_556 . . . 5.5(2) no
    N3 Ni1 N3 C6 5_556 . . .  -3E1(10)
                                      no
    O1 Ni1 N3 C6 5_556 . . . 97.3(2) no
    O1 Ni1 N3 C6 . . . . -82.7(2) no
    C2 N2 C1 N1 . . . .  .1(3) no
    C3 N1 C1 N2 . . . .  -.2(3) no
    Ni1 N1 C1 N2 . . . . 173.9(2) no
    C1 N2 C2 C3 . . . .  .1(3) no
    N2 C2 C3 N1 . . . .  -.3(3) no
    C1 N1 C3 C2 . . . .  .3(3) no
    Ni1 N1 C3 C2 . . . . -173.9(2) no
    C6 N3 C4 N4 . . . .  -.5(3) no
    Ni1 N3 C4 N4 . . . . 170.9(2) no
    C5 N4 C4 N3 . . . .  .8(3) no
    C4 N4 C5 C6 . . . .  -.8(3) no
    N4 C5 C6 N3 . . . .  .6(4) no
    C4 N3 C6 C5 . . . .  -.1(3) no
    Ni1 N3 C6 C5 . . . . -171.3(2) no
    Ni1 O1 C7 O2 . . . . 98.8(3) no
    Ni1 O1 C7 C8 . . . . -80.9(3) no
loop_
    _geom_hbond_atom_site_label_D
    _geom_hbond_atom_site_label_H
    _geom_hbond_atom_site_label_A
    _geom_hbond_site_symmetry_A
    _geom_hbond_distance_DH
    _geom_hbond_distance_HA
    _geom_hbond_distance_DA
    _geom_hbond_angle_DHA
    _geom_hbond_publ_flag
    N2 H2 O2 4  .86 1.82 2.679(3) 175.3 yes
    N4 H4 O1 3  .86 2.01 2.870(4) 175.2 yes
data_global
_journal_data_validation_number     IUC0000197
_journal_date_recd_electronic     2000-07-10
_journal_date_accepted     2000-07-17
_journal_name_full     'Acta Crystallographica, Section C'
_journal_year     2000
_journal_volume     56
_journal_issue      9
_journal_page_first     e372
_journal_page_last     e373
_journal_paper_category     CM
_publ_contact_author_name     'Assoc. Prof. Seik Weng Ng'
_publ_contact_author_address
;
Institute of Postgraduate Studies and Research
University of Malaya
50603 Kuala Lumpur
Malaysia
;
_publ_contact_author_email     h1nswen@umcsd.um.edu.my
_publ_contact_author_fax     '03 756 8940'
_publ_contact_author_phone     '03 759 4414'
_publ_section_title
;
Bis(acetato-O)tetrakis(imidazole-N³)nickel(II)
;
loop_
    _publ_author_name
    _publ_author_address
    'Naumov, Pance'
;
Institute of Chemistry
Faculty of Science
"Sv. Kiril i Metodij" University
PO Box 162
MK-91001 Skopje
Macedonia
;
    'Ristova, Mirjana'
;
Institute of Chemistry
Faculty of Science
"Sv. Kiril i Metodij" University
PO Box 162
MK-91001 Skopje
Macedonia
;
    'Drew, Michael G. B.'
;
Department of Chemistry
University of Reading
Reading RG6 2AD
England
;
    'Ng, Seik Weng'
;
Institute of Postgraduate Studies and Research
University of Malaya
50603 Kuala Lumpur
Malaysia
;
_publ_section_synopsis
;
In the title compound, the Ni atom is bonded centrosymmetrically
by four N and two O atoms in a distorted octahedral coordination.
The acetate ligands form intermolecular hydrogen bonds to imidazole
moieties, giving rise to a two-dimensional layer structure.
;
_publ_section_abstract
;
In the title compound, [Ni(C₂H₃O)₂(C₃H₄N₃)₄], the Ni atom is
coordinated centrosymmetrically by four N and two O atoms in an octahedral
coordination [Ni---N = 1.986(3) and 2.054(3)Å; Ni---O = 2.697(3)Å]. The O
atoms of the acetate anions form hydrogen bonds to adjacent imidazole moieties,
with the free O atom forming a somewhat shorter bond [N...O = 2.679(3) and
2.870(4)Å]. The hydrogen bonds give rise to a two-dimensional layer
structure.
;
_publ_section_comment
;
Interest in the chemistry of transition metal complexes of imidazole and
substituted imidazoles stems from attempts to model the binding site of
the histidine residue in metalloproteins (Henriksson, 1977; Povse et al.,
1998; Wang et al., 2000). The structures of the complexes constitute the
primary source of input data for semi-empirical theoretical modeling of
metal--DNA and metal--protein interactions (Abuhijleh & Woods, 1992). The
copper(II) systems have been most well documented (Abuhijleh & Woods, 1992;
Fransson & Lundberg, 1972; Henriksson, 1977; Lundberg, 1972). Following the
synthesis of the hexakis(imidazole)nickel(II) halides (Eilbeck et al., 1967),
other hexakis(imidazole)nickel adducts were prepared and structurally
characterized (Konopelski et al., 1976; Perec et al., 1999; Povse et al.,
1998; Santoro et al., 1969; van Ingen Schenau, 1975; Wang et al., 2000).
Four imidazole ligands pack around the Ni atom in
tetrakis(imidazole-N³)nickel isothiocyanate (Koman et al., 1991), whose
Ni atom shows octahedral coordination.
With the acetate ion as the counter-ion, only four imidazole ligands
pack around the Ni atom in the title compound,
bis(acetato-O)tetrakis(imidazole-N³)nickel(II), (I), which is
isostructural with the copper analog (Abuhijleh & Woods, 1992). As expected,
the Ni---N distances are shorter than those found in the six-coordinate
hexakis and the four-coordinate tetrakis compounds (See et al., 1998). The
six-coordinate geometry arises from two relatively long Ni---O distances
[2.697(3)Å]; the bonds are somewhat longer than the Jahn--Teller elongated
bonds in the copper analog (Abuhijleh & Woods, 1992). The acetate groups
permit the imidazole ligands to approach the metal atom closer than the
isothiocyanate ions in the nickel isothiocyanate adduct (Koman et al., 1991)
and the water molecules in the dihydrated nickel saccharinate adduct (Zhang
et al., 1992).
The negative charge is delocalized over the acetate ions; both O atoms form
hydrogen bonds to adjacent imidazole moieties.  The uncoordinated O atom is
engaged in a somewhat stronger hydrogen bond [N...O = 2.679(3) and
2.870(4)Å]. Hydrogen bonding gives rise to a two-dimensional layered
structure.
;
_publ_section_acknowledgements
;
We thank the Macedonian Academy of Sciences and Arts and the National Science
Council for R&D, Malaysia (IRPA 09-02-03-0662), for supporting this work.
The University of Reading provided the funds for the Image Plate
diffractometer.
;
_publ_section_references
;
Abuhijleh, A.L. & Woods, C. (1992). Inorg. Chim. Acta, 194, 9-14.
Eilbeck, W. J., Holmes, F. & Underhill, A. E. (1967). J. Chem. Soc. A,
pp. 757-761.
Fransson, G. & Lundberg, K. S. B. (1972). Acta Chem. Scand. 26, 3969-3976.
Henriksson, Å. (1977).  Acta Cryst. B33, 1947-1950.
Ingen Schenau, A. D. van  (1975). Acta Cryst. B31, 2736-2738.
Kabsch, W. (1988).  J. Appl. Cryst. 21, 916-932.
Koman, M., Jona, E. & Maslejova, A. (1991). Acta Cryst. C47, 1206-1208.
Konopelski, J.P., Reimann, C.W., Hubbard, C.R., Mighell, A.D. & Santoro, A.
(1976). Acta Cryst. B32, 2911-2913.
Lundberg, K. S. B. (1972). Acta Chem. Scand. 26, 3977-3983.
Perec, M., Baggio, R. & Garland, M. T. (1999). Acta Cryst. C55, 858-860.
Povse, V., Perec, M., Baggio, R. & Garland, M. T. (1998). Acta Cryst. C54,
1817-1820.
Santoro, A., Mighell, A. D., Zocchi, M. & Reimann, C. W. (1969).
Acta Cryst. B25, 842-847.
See, R. F., Kruse, R. A. & Strub, W. M. (1998). Inorg. Chem. 37, 5369-5375.
Sheldrick, G. M. (1997).  SHELXS97 and SHELXL97. University of Göttingen,
Germany.
Wang, Z., Zhang, Y., Razak, I. A., Shanmuga Sundara Raj, S., Fun, H.-K.,
Li, F. & Song, H. (2000).  Acta Cryst. C56, 161-162.
Zhang, Y., Li, J., Lin, W., Liu, S. & Huang, J. (1992).  J. Crystallogr.
Spectrosc. Res. 22, 433-438.
;
_publ_section_exptl_prep
;
Nickel acetate and imidazole (1:4 stoichiometry) were heated in n-propanol
to furnish the title compound as an oil after the solvent had been removed.
The solid compound was obtained as crystals after recrystallization from
absolute ethanol.
;
_publ_section_exptl_refinement
;
Distances involving H atoms were constrained to N---H = 0.86Å and C---H
0.93--0.96Å.
;
