#------------------------------------------------------------------------------
#$Date: 2008-04-03 13:11:48 +0300 (Thu, 03 Apr 2008) $
#$Revision: 326 $
#$URL: file:///home/coder/svn-repositories/cod/cif/2/2102095.cif $
#------------------------------------------------------------------------------
#
# This file is available in the Crystallography Open Database (COD),
# http://www.crystallography.net/
#
# All data on this site have been placed in the public domain by the
# contributors.
#
data_2102095
loop_
_publ_author_name
'Boese, Roland'
'Gehrke, Annette'
'Kapon, Moshe'
'Herbstein, Frank H.'
_publ_section_title
;
 Determining the crystal structure of twinned 2-methylpyrazine
;
_journal_issue                   4
_journal_name_full               'Acta Crystallographica Section B'
_journal_page_first              677
_journal_page_last               681
_journal_volume                  56
_journal_year                    2000
_chemical_formula_sum            'C5 H6 N2'
_chemical_formula_weight         94.12
_chemical_melting_point          242
_chemical_name_common            2-Methylpyrazine
_chemical_name_systematic        ' pyrazine, 2-methyl'
_symmetry_cell_setting           Tetragonal
_symmetry_space_group_name_H-M   I-4
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            16
_cell_length_a                   13.725(2)
_cell_length_b                   13.725(2)
_cell_length_c                   10.859(2)
_cell_measurement_reflns_used    50
_cell_measurement_temperature    123(2)
_cell_measurement_theta_max      45
_cell_measurement_theta_min      3
_cell_volume                     2045.6(6)
_computing_cell_refinement
;
'Siemens P3-PC diffractometer program V.4.24'
;
_computing_data_collection
;
'Siemens P3-PC diffractometer program V.4.24'
;
_computing_data_reduction        ' Siemens XDISK V.4.20.2 1991 PC'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      123(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'Nicolet R3m/V four circle diffractometer'
_diffrn_measurement_method       'Wyckoff scan mode'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     .71073
_diffrn_reflns_av_R_equivalents  .0241
_diffrn_reflns_av_sigmaI/netI    .0229
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -14
_diffrn_reflns_limit_k_max       14
_diffrn_reflns_limit_k_min       -10
_diffrn_reflns_limit_l_max       11
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            1474
_diffrn_reflns_theta_full        22.50
_diffrn_reflns_theta_max         22.50
_diffrn_reflns_theta_min         2.10
_diffrn_standards_decay_%        .7
_diffrn_standards_interval_count 100
_diffrn_standards_number         2
_exptl_absorpt_coefficient_mu    .079
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.222
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       cylindrical
_exptl_crystal_F_000             800
_exptl_crystal_size_rad          .15
_refine_diff_density_max         .086
_refine_diff_density_min         -.124
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -6(3)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.082
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     176
_refine_ls_number_reflns         1338
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.082
_refine_ls_R_factor_all          .0270
_refine_ls_R_factor_gt           .0257
_refine_ls_shift/su_max          .004
_refine_ls_shift/su_mean         .001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0428P)^2^+0.2414P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_ref         .0679
_reflns_number_gt                1301
_reflns_number_total             1338
_reflns_threshold_expression     >2sigma(I)
_[local]_cod_data_source_file    cf0007.cif
loop_
_symmetry_equiv_pos_as_xyz
'x, y, z'
'-x, -y, z'
'y, -x, -z'
'-y, x, -z'
'x+1/2, y+1/2, z+1/2'
'-x+1/2, -y+1/2, z+1/2'
'y+1/2, -x+1/2, -z+1/2'
'-y+1/2, x+1/2, -z+1/2'
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'
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_occupancy
_atom_site_type_symbol
N1A .01857(15) .13349(14) .15884(18) .0377(6) Uani d 1 N
C2A .04218(18) .13973(16) .2772(2) .0310(6) Uani d 1 C
C3A -.0289(2) .12985(19) .3668(2) .0381(6) Uani d 1 C
H3A -.0139(18) .137(2) .443(3) .040(7) Uiso d 1 H
N4A -.12254(16) .11445(18) .34271(19) .0437(6) Uani d 1 N
C5A -.1452(2) .1090(2) .2227(3) .0427(7) Uani d 1 C
H5A -.209(2) .0954(19) .198(3) .046(8) Uiso d 1 H
C6A -.0756(2) .11701(19) .1330(2) .0416(7) Uani d 1 C
H6A -.095(2) .111(2) .040(3) .077(10) Uiso d 1 H
C7A .1464(2) .1572(3) .3096(3) .0452(8) Uani d 1 C
H7A1 .190(3) .104(3) .270(4) .084(11) Uiso d 1 H
H7A2 .154(2) .156(3) .396(3) .067(10) Uiso d 1 H
H7A3 .166(2) .214(2) .273(3) .048(9) Uiso d 1 H
N1B -.52689(17) .12727(17) -.09554(18) .0414(6) Uani d 1 N
C2B -.55250(18) .13104(18) .0227(2) .0349(6) Uani d 1 C
C3B -.48228(19) .12616(19) .1148(2) .0369(6) Uani d 1 C
H3B -.4996(17) .1288(17) .203(2) .034(6) Uiso d 1 H
N4B -.38712(16) .11870(17) .09235(19) .0391(6) Uani d 1 N
C5B -.3620(2) .11554(19) -.0264(3) .0386(6) Uani d 1 C
H5B -.287(2) .113(2) -.041(3) .048(7) Uiso d 1 H
C6B -.4314(2) .11949(19) -.1188(3) .0432(7) Uani d 1 C
H6B -.4053(19) .109(2) -.196(3) .050(9) Uiso d 1 H
C7B -.6584(2) .1387(2) .0524(3) .0438(7) Uani d 1 C
H7B1 -.694(3) .113(4) -.028(5) .136(17) Uiso d 1 H
H7B2 -.683(3) .204(3) .053(4) .086(12) Uiso d 1 H
H7B3 -.682(3) .090(3) .105(4) .099(14) Uiso d 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
N1A .0449(15) .0395(13) .0287(12) -.0016(11) .0045(9) -.0019(10)
C2A .0393(14) .0276(13) .0261(12) .0004(12) -.0001(11) -.0002(10)
C3A .0441(17) .0450(15) .0251(15) .0013(12) -.0035(12) .0010(13)
N4A .0391(13) .0563(15) .0359(11) -.0011(11) .0001(10) .0050(11)
C5A .0392(17) .0440(17) .0449(16) .0008(15) -.0070(15) .0059(14)
C6A .0583(18) .0411(15) .0253(15) .0018(13) -.0089(14) .0010(12)
C7A .0418(16) .053(2) .0409(18) -.0026(15) .0044(13) -.0006(16)
N1B .0547(16) .0461(14) .0234(12) .0020(11) -.0029(10) -.0046(10)
C2B .0425(15) .0287(13) .0334(16) -.0072(12) -.0022(12) -.0017(11)
C3B .0494(17) .0386(14) .0226(14) -.0030(12) .0009(12) .0021(11)
N4B .0393(13) .0449(13) .0333(12) -.0026(10) -.0026(10) -.0029(10)
C5B .0430(16) .0342(13) .0387(16) .0004(12) .0097(13) -.0029(13)
C6B .0602(19) .0403(17) .0292(16) .0041(14) .0063(16) -.0045(13)
C7B .0421(17) .0393(18) .0500(19) .0028(14) -.0005(13) .0011(15)
loop_
_geom_bond_atom_site_label_1
_geom_bond_atom_site_label_2
_geom_bond_distance
N1A C2A 1.328(3)
N1A C6A 1.342(4)
C2A C3A 1.384(4)
C2A C7A 1.492(4)
C3A N4A 1.329(4)
N4A C5A 1.342(3)
C5A C6A 1.368(4)
N1B C2B 1.332(3)
N1B C6B 1.339(4)
C2B C3B 1.391(4)
C2B C7B 1.492(4)
C3B N4B 1.332(4)
N4B C5B 1.335(4)
C5B C6B 1.385(4)
loop_
_geom_angle_atom_site_label_1
_geom_angle_atom_site_label_2
_geom_angle_atom_site_label_3
_geom_angle
C2A N1A C6A 116.6(2)
N1A C2A C3A 120.1(2)
N1A C2A C7A 118.2(2)
C3A C2A C7A 121.7(2)
N4A C3A C2A 124.0(2)
C3A N4A C5A 115.1(2)
N4A C5A C6A 121.6(3)
N1A C6A C5A 122.5(2)
C2B N1B C6B 116.3(2)
N1B C2B C3B 120.5(2)
N1B C2B C7B 117.9(2)
C3B C2B C7B 121.5(2)
N4B C3B C2B 123.5(3)
C3B N4B C5B 115.6(2)
N4B C5B C6B 121.4(3)
N1B C6B C5B 122.7(3)