# Supplementary Material (ESI) for Perkin Transactions
# This journal is © The Royal Society of Chemistry 1999
# CCDC Number: 207/377


data_1

_audit_creation_method            SHELXL-97
_chemical_name_systematic
;
 ?
;
_chemical_name_common             ?
_chemical_formula_moiety          ?
_chemical_formula_sum
 'C21 H26 N2 O8'
_chemical_formula_weight          434.44

loop_
 _atom_type_symbol
 _atom_type_description
 _atom_type_scat_dispersion_real
 _atom_type_scat_dispersion_imag
 _atom_type_scat_source
 'C'  'C'   0.0033   0.0016
 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
 'H'  'H'   0.0000   0.0000
 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
 'N'  'N'   0.0061   0.0033
 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
 'O'  'O'   0.0106   0.0060
 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'

_symmetry_cell_setting            monoclinic
_symmetry_space_group_name_H-M    C2

loop_
 _symmetry_equiv_pos_as_xyz
 'x, y, z'
 '-x, y, -z'
 'x+1/2, y+1/2, z'
 '-x+1/2, y+1/2, -z'

_cell_length_a                    37.76(4)
_cell_length_b                    5.740(6)
_cell_length_c                    10.910(12)
_cell_angle_alpha                 90.00
_cell_angle_beta                  98.240(10)
_cell_angle_gamma                 90.00
_cell_volume                      2340(4)
_cell_formula_units_Z             4
_cell_measurement_temperature     293(2)
_cell_measurement_reflns_used     all
_cell_measurement_theta_min       ?
_cell_measurement_theta_max       ?

_exptl_crystal_description        ?
_exptl_crystal_colour             ?
_exptl_crystal_size_max           0.25
_exptl_crystal_size_mid           0.25
_exptl_crystal_size_min           0.20
_exptl_crystal_density_meas       ?
_exptl_crystal_density_diffrn     1.233
_exptl_crystal_density_method     'not measured'
_exptl_crystal_F_000              920
_exptl_absorpt_coefficient_mu     0.095
_exptl_absorpt_correction_type    none
_exptl_absorpt_correction_T_min   ?
_exptl_absorpt_correction_T_max   ?

_exptl_special_details
;
 ?
;

_diffrn_ambient_temperature       293(2)
_diffrn_radiation_wavelength      0.71073
_diffrn_radiation_type            MoK\a
_diffrn_radiation_source          'fine-focus sealed tube'
_diffrn_radiation_monochromator   graphite
_diffrn_measurement_device        'Marresearch Image Plate'
_diffrn_measurement_method
  '95 frames at 2^o intervals, counting time 2 min.'
_diffrn_detector_area_resol_mean  ?
_diffrn_standards_number          ?
_diffrn_standards_interval_count  ?
_diffrn_standards_interval_time   ?
_diffrn_standards_decay_%         ?
_diffrn_reflns_number             1367
_diffrn_reflns_av_R_equivalents   0.0215
_diffrn_reflns_av_sigmaI/netI     0.0251
_diffrn_reflns_limit_h_min        0
_diffrn_reflns_limit_h_max        44
_diffrn_reflns_limit_k_min        -4
_diffrn_reflns_limit_k_max        6
_diffrn_reflns_limit_l_min        -5
_diffrn_reflns_limit_l_max        4
_diffrn_reflns_theta_min          2.67
_diffrn_reflns_theta_max          24.99
_reflns_number_total              1361
_reflns_number_gt                 1071
_reflns_threshold_expression      >2sigma(I)

_computing_data_collection        'XDS (Kabsch, 1991)'
_computing_cell_refinement        XDS
_computing_data_reduction         XDS
_computing_structure_solution     'SHELXS-86 (Sheldrick, 1990)'
_computing_structure_refinement   'SHELXL-93 (Sheldrick, 1993)'
_computing_molecular_graphics     'PLATON(Spek,1994)'

_refine_special_details
;
 Refinement of F^2^ against ALL reflections.  The weighted R-factor wR 
and
 goodness of fit S are based on F^2^, conventional R-factors R are based
 on F, with F set to zero for negative F^2^. The threshold expression of
 F^2^ > 2sigma(F^2^) is used only for calculating R-factors(gt) etc. and 
is
 not relevant to the choice of reflections for refinement.  R-factors 
based
 on F^2^ are statistically about twice as large as those based on F, and 
R-
 factors based on ALL data will be even larger.
;

_refine_ls_structure_factor_coef  Fsqd
_refine_ls_matrix_type            full
_refine_ls_weighting_scheme
 'calc w=1/[\s^2^(Fo^2^)+(0.1922P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_atom_sites_solution_primary      direct
_atom_sites_solution_secondary    difmap
_atom_sites_solution_hydrogens    geom
_refine_ls_hydrogen_treatment     mixed
_refine_ls_extinction_method      SHELXL
_refine_ls_extinction_coef        0.111(14)
_refine_ls_extinction_expression
 'Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^'
_refine_ls_abs_structure_details
 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack    1(3)
_refine_ls_number_reflns          1361
_refine_ls_number_parameters      285
_refine_ls_number_restraints      37
_refine_ls_R_factor_all           0.0923
_refine_ls_R_factor_gt            0.0737
_refine_ls_wR_factor_ref          0.2048
_refine_ls_wR_factor_gt           0.1831
_refine_ls_goodness_of_fit_ref    1.012
_refine_ls_restrained_S_all       0.997
_refine_ls_shift/su_max           0.014
_refine_ls_shift/su_mean          0.002

loop_
 _atom_site_label
 _atom_site_type_symbol
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_U_iso_or_equiv
 _atom_site_adp_type
 _atom_site_occupancy
 _atom_site_calc_flag
 _atom_site_refinement_flags
 _atom_site_disorder_assembly
 _atom_site_disorder_group
C1 C 0.27693(16) 0.2062(14) 0.2306(12) 0.065(6) Uani 1 d U . .
C2 C 0.25012(17) 0.0996(13) 0.1526(14) 0.069(6) Uani 1 d U . .
H2 H 0.2551 -0.0321 0.1085 0.083 Uiso 1 calc R . .
C3 C 0.21471(16) 0.1892(13) 0.1388(13) 0.057(5) Uani 1 d U . .
C4 C 0.20779(18) 0.3820(13) 0.2138(14) 0.073(5) Uani 1 d U . .
H4 H 0.1848 0.4432 0.2094 0.088 Uiso 1 calc R . .
C5 C 0.23592(17) 0.4765(12) 0.2931(13) 0.066(5) Uani 1 d U . .
C6 C 0.27183(17) 0.3984(12) 0.3042(14) 0.064(5) Uani 1 d U . .
H6 H 0.2904 0.4693 0.3561 0.077 Uiso 1 calc R . .
N51 N 0.22924(17) 0.6814(12) 0.3729(12) 0.091(6) Uani 1 d . . .
O52 O 0.19763(15) 0.7236(13) 0.3830(12) 0.130(6) Uani 1 d . . .
O53 O 0.25525(17) 0.7963(10) 0.4189(12) 0.106(5) Uani 1 d . . .
N11 N 0.31403(18) 0.1078(15) 0.2424(13) 0.087(6) Uani 1 d . . .
O12 O 0.33861(13) 0.2171(11) 0.2998(11) 0.110(5) Uani 1 d . . .
O13 O 0.31724(15) -0.0867(14) 0.1934(12) 0.116(5) Uani 1 d . . .
C31 C 0.18731(19) 0.0747(15) 0.0464(16) 0.095(7) Uani 1 d . . .
O32 O 0.19286(13) -0.1006(11) -0.0126(11) 0.101(5) Uani 1 d . . .
O33 O 0.15560(11) 0.1973(8) 0.0304(9) 0.070(4) Uani 1 d . . .
C34 C 0.12735(16) 0.1098(13) -0.0700(14) 0.070(7) Uani 1 d . . .
H34A H 0.1386 0.0200 -0.1291 0.084 Uiso 1 calc R . .
H34B H 0.1153 0.2416 -0.1135 0.084 Uiso 1 calc R . .
C35 C 0.09961(17) -0.0428(12) -0.0180(13) 0.054(7) Uani 1 d . . .
C36 C 0.07327(19) -0.1196(15) -0.1322(15) 0.083(7) Uani 1 d . . .
H36A H 0.0620 0.0185 -0.1713 0.099 Uiso 1 calc R . .
H36B H 0.0869 -0.1917 -0.1910 0.099 Uiso 1 calc R . .
C37 C 0.0439(2) -0.2893(19) -0.1070(16) 0.112(8) Uani 1 d . . .
H37A H 0.0278 -0.2105 -0.0586 0.135 Uiso 1 calc R . .
H37B H 0.0547 -0.4188 -0.0582 0.135 Uiso 1 calc R . .
C38 C 0.0214(3) -0.387(3) -0.230(2) 0.147(9) Uani 1 d . . .
H38A H 0.0099 -0.2586 -0.2781 0.176 Uiso 1 calc R . .
H38B H 0.0373 -0.4641 -0.2794 0.176 Uiso 1 calc R . .
C39 C -0.0069(4) -0.558(3) -0.200(3) 0.231(16) Uani 1 d . . .
H39A H 0.0042 -0.6783 -0.1464 0.277 Uiso 1 calc R . .
H39B H -0.0187 -0.6271 -0.2751 0.277 Uiso 1 calc R . .
H39C H -0.0242 -0.4776 -0.1591 0.277 Uiso 1 calc R . .
C41 C 0.1177(3) -0.2453(18) 0.052(2) 0.092(14) Uani 1 d . . .
H41 H 0.1284 -0.3665 0.0146 0.111 Uiso 1 calc R . .
C42 C 0.1169(3) -0.2348(19) 0.176(3) 0.101(14) Uani 1 d . . .
H42 H 0.1264 -0.3490 0.2313 0.121 Uiso 1 calc R . .
C43 C 0.0983(2) -0.0100(14) 0.2133(19) 0.081(9) Uani 1 d . . .
C44 C 0.08222(19) 0.0868(15) 0.0893(16) 0.072(7) Uani 1 d . . .
H44A H 0.0868 0.2529 0.0865 0.086 Uiso 1 calc R . .
H44B H 0.0565 0.0630 0.0769 0.086 Uiso 1 calc R . .
O45 O 0.12355(16) 0.1443(12) 0.2844(13) 0.102(7) Uani 1 d . . .
O46 O 0.07077(19) -0.0569(19) 0.2879(18) 0.105(8) Uani 1 d . . .
C47 C 0.1101(3) 0.2006(19) 0.402(2) 0.110(8) Uani 1 d . . .
H47 H 0.0964 0.3462 0.3932 0.131 Uiso 1 calc R . .
C48 C 0.0852(4) -0.006(3) 0.411(3) 0.102(14) Uani 1 d . . .
H48 H 0.0999 -0.1384 0.4439 0.123 Uiso 1 calc R . .
C49 C 0.1434(4) 0.229(3) 0.498(2) 0.145(11) Uani 1 d . . .
H49A H 0.1506 0.0797 0.5322 0.174 Uiso 1 calc R . .
H49B H 0.1381 0.3310 0.5625 0.174 Uiso 1 calc R . .
H49C H 0.1624 0.2945 0.4589 0.174 Uiso 1 calc R . .
C50 C 0.0565(4) 0.036(4) 0.499(3) 0.195(12) Uani 1 d . . .
H50A H 0.0414 0.1648 0.4680 0.234 Uiso 1 calc R . .
H50B H 0.0681 0.0713 0.5806 0.234 Uiso 1 calc R . .
H50C H 0.0421 -0.1012 0.5009 0.234 Uiso 1 calc R . .

loop_
 _atom_site_aniso_label
 _atom_site_aniso_U_11
 _atom_site_aniso_U_22
 _atom_site_aniso_U_33
 _atom_site_aniso_U_23
 _atom_site_aniso_U_13
 _atom_site_aniso_U_12
C1 0.056(3) 0.077(4) 0.060(18) -0.016(6) -0.001(5) 0.001(3)
C2 0.076(4) 0.070(4) 0.065(19) 0.005(6) 0.023(6) 0.008(3)
C3 0.061(3) 0.073(4) 0.037(15) -0.018(6) 0.005(5) -0.004(3)
C4 0.065(3) 0.070(4) 0.087(17) -0.010(6) 0.018(5) -0.001(3)
C5 0.075(4) 0.059(3) 0.062(17) -0.015(6) 0.000(6) 0.005(3)
C6 0.069(3) 0.066(4) 0.056(17) 0.000(7) 0.008(5) 0.002(3)
N51 0.091(4) 0.068(3) 0.11(2) -0.026(6) 0.009(6) 0.007(3)
O52 0.090(3) 0.126(5) 0.172(18) -0.072(8) 0.007(5) 0.023(3)
O53 0.109(4) 0.074(3) 0.132(17) -0.021(5) 0.010(5) -0.019(3)
N11 0.076(4) 0.104(6) 0.082(19) 0.016(7) 0.014(6) 0.019(4)
O12 0.063(3) 0.113(5) 0.150(16) 0.004(6) -0.002(4) 0.007(3)
O13 0.100(3) 0.121(5) 0.123(17) -0.045(7) 0.003(5) 0.040(4)
C31 0.068(4) 0.078(5) 0.14(2) -0.012(8) 0.038(7) -0.003(3)
O32 0.082(3) 0.092(4) 0.129(15) -0.046(6) 0.014(5) -0.001(3)
O33 0.067(2) 0.066(2) 0.076(12) -0.016(4) 0.007(4) -0.0070(19)
C34 0.065(3) 0.068(4) 0.07(2) 0.001(6) -0.003(6) -0.013(3)
C35 0.067(4) 0.066(4) 0.03(2) 0.002(6) -0.004(6) -0.002(3)
C36 0.077(4) 0.080(4) 0.09(2) -0.018(8) -0.011(6) -0.018(3)
C37 0.087(5) 0.106(7) 0.14(3) 0.027(10) -0.011(7) -0.030(5)
C38 0.129(8) 0.191(14) 0.11(3) -0.007(15) -0.032(11) -0.085(9)
C39 0.140(8) 0.195(16) 0.36(5) -0.09(2) 0.048(15) -0.089(10)
C41 0.081(5) 0.055(4) 0.14(4) -0.003(10) 0.025(13) -0.008(3)
C42 0.067(4) 0.066(5) 0.17(4) 0.032(12) 0.018(12) 0.000(3)
C43 0.067(4) 0.067(4) 0.10(3) 0.005(8) -0.022(7) -0.007(3)
C44 0.069(4) 0.075(4) 0.07(2) 0.002(8) 0.015(7) 0.001(3)
O45 0.084(4) 0.107(5) 0.11(2) 0.008(7) -0.013(6) -0.018(3)
O46 0.088(4) 0.151(7) 0.08(3) 0.001(9) 0.021(6) -0.019(4)
C47 0.112(7) 0.094(6) 0.12(3) 0.008(10) 0.014(12) 0.013(5)
C48 0.132(10) 0.118(9) 0.07(5) 0.013(13) 0.052(15) 0.005(7)
C49 0.181(13) 0.165(13) 0.08(4) -0.046(18) 0.002(16) -0.013(11)
C50 0.179(11) 0.219(18) 0.20(4) 0.00(2) 0.080(15) -0.011(13)

_geom_special_details
;
 All esds (except the esd in the dihedral angle between two l.s. planes)
 are estimated using the full covariance matrix.  The cell esds are 
taken
 into account individually in the estimation of esds in distances, 
angles
 and torsion angles; correlations between esds in cell parameters are 
only
 used when they are defined by crystal symmetry.  An approximate 
(isotropic)
 treatment of cell esds is used for estimating esds involving l.s. 
planes.
;

loop_
 _geom_bond_atom_site_label_1
 _geom_bond_atom_site_label_2
 _geom_bond_distance
 _geom_bond_site_symmetry_2
 _geom_bond_publ_flag
C1 C6 1.395(15) . ?
C1 C2 1.369(14) . ?
C1 N11 1.499(9) . ?
C2 C3 1.420(9) . ?
C3 C4 1.423(14) . ?
C3 C31 1.489(16) . ?
C4 C5 1.381(14) . ?
C5 C6 1.417(9) . ?
C5 N51 1.506(14) . ?
N51 O53 1.229(10) . ?
N51 O52 1.238(8) . ?
N11 O12 1.217(12) . ?
N11 O13 1.251(13) . ?
C31 O32 1.228(13) . ?
C31 O33 1.378(9) . ?
O33 C34 1.502(14) . ?
C34 C35 1.535(11) . ?
C35 C41 1.502(19) . ?
C35 C36 1.543(18) . ?
C35 C44 1.605(19) . ?
C36 C37 1.531(11) . ?
C37 C38 1.58(2) . ?
C38 C39 1.523(17) . ?
C41 C42 1.35(3) . ?
C42 C43 1.552(16) . ?
C43 O45 1.443(14) . ?
C43 O46 1.44(2) . ?
C43 C44 1.51(2) . ?
O45 C47 1.48(2) . ?
O46 C48 1.41(3) . ?
C47 C48 1.52(2) . ?
C47 C49 1.52(2) . ?
C48 C50 1.56(3) . ?

loop_
 _geom_angle_atom_site_label_1
 _geom_angle_atom_site_label_2
 _geom_angle_atom_site_label_3
 _geom_angle
 _geom_angle_site_symmetry_1
 _geom_angle_site_symmetry_3
 _geom_angle_publ_flag
C6 C1 C2 124.1(7) . . ?
C6 C1 N11 116.9(9) . . ?
C2 C1 N11 118.9(9) . . ?
C1 C2 C3 120.3(9) . . ?
C4 C3 C2 117.9(10) . . ?
C4 C3 C31 124.4(7) . . ?
C2 C3 C31 117.6(9) . . ?
C5 C4 C3 118.6(6) . . ?
C4 C5 C6 124.7(9) . . ?
C4 C5 N51 119.4(6) . . ?
C6 C5 N51 115.8(9) . . ?
C1 C6 C5 114.2(9) . . ?
O53 N51 O52 125.6(9) . . ?
O53 N51 C5 117.7(6) . . ?
O52 N51 C5 116.6(8) . . ?
O12 N11 O13 124.5(7) . . ?
O12 N11 C1 119.0(9) . . ?
O13 N11 C1 116.5(9) . . ?
O32 C31 O33 124.2(11) . . ?
O32 C31 C3 124.2(7) . . ?
O33 C31 C3 111.5(8) . . ?
C31 O33 C34 115.8(8) . . ?
O33 C34 C35 111.9(11) . . ?
C41 C35 C34 110.3(6) . . ?
C41 C35 C36 112.6(9) . . ?
C34 C35 C36 105.0(11) . . ?
C41 C35 C44 100.9(13) . . ?
C34 C35 C44 112.1(7) . . ?
C36 C35 C44 116.0(6) . . ?
C37 C36 C35 115.9(12) . . ?
C36 C37 C38 112.8(13) . . ?
C39 C38 C37 110.7(16) . . ?
C42 C41 C35 113.7(13) . . ?
C41 C42 C43 112.1(19) . . ?
O45 C43 O46 106.6(15) . . ?
O45 C43 C44 114.0(8) . . ?
O46 C43 C44 110.2(9) . . ?
O45 C43 C42 111.4(9) . . ?
O46 C43 C42 112.7(9) . . ?
C44 C43 C42 102.0(17) . . ?
C43 C44 C35 109.2(8) . . ?
C43 O45 C47 108.6(10) . . ?
C48 O46 C43 106.8(11) . . ?
O45 C47 C48 100.4(15) . . ?
O45 C47 C49 105.5(11) . . ?
C48 C47 C49 119.5(17) . . ?
O46 C48 C47 105(2) . . ?
O46 C48 C50 114.0(16) . . ?
C47 C48 C50 114.3(16) . . ?

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
 _geom_torsion_site_symmetry_1
 _geom_torsion_site_symmetry_2
 _geom_torsion_site_symmetry_3
 _geom_torsion_site_symmetry_4
 _geom_torsion_publ_flag
C6 C1 C2 C3 3(2) . . . . ?
N11 C1 C2 C3 -179.7(10) . . . . ?
C1 C2 C3 C4 -3.9(18) . . . . ?
C1 C2 C3 C31 176.1(10) . . . . ?
C2 C3 C4 C5 1.9(16) . . . . ?
C31 C3 C4 C5 -178.0(10) . . . . ?
C3 C4 C5 C6 1.4(18) . . . . ?
C3 C4 C5 N51 179.7(10) . . . . ?
C2 C1 C6 C5 0.5(18) . . . . ?
N11 C1 C6 C5 -177.2(9) . . . . ?
C4 C5 C6 C1 -2.6(18) . . . . ?
N51 C5 C6 C1 179.0(11) . . . . ?
C4 C5 N51 O53 -162.6(11) . . . . ?
C6 C5 N51 O53 15.9(16) . . . . ?
C4 C5 N51 O52 15.1(17) . . . . ?
C6 C5 N51 O52 -166.4(12) . . . . ?
C6 C1 N11 O12 -10.8(17) . . . . ?
C2 C1 N11 O12 171.4(11) . . . . ?
C6 C1 N11 O13 167.9(12) . . . . ?
C2 C1 N11 O13 -10.0(17) . . . . ?
C4 C3 C31 O32 -175.3(13) . . . . ?
C2 C3 C31 O32 4.8(19) . . . . ?
C4 C3 C31 O33 8.1(16) . . . . ?
C2 C3 C31 O33 -171.8(10) . . . . ?
O32 C31 O33 C34 -2.4(17) . . . . ?
C3 C31 O33 C34 174.1(8) . . . . ?
C31 O33 C34 C35 98.7(10) . . . . ?
O33 C34 C35 C41 -57.6(14) . . . . ?
O33 C34 C35 C36 -179.2(6) . . . . ?
O33 C34 C35 C44 54.0(10) . . . . ?
C41 C35 C36 C37 56.0(12) . . . . ?
C34 C35 C36 C37 176.1(8) . . . . ?
C44 C35 C36 C37 -59.5(10) . . . . ?
C35 C36 C37 C38 -172.0(9) . . . . ?
C36 C37 C38 C39 178.8(11) . . . . ?
C34 C35 C41 C42 111.6(13) . . . . ?
C36 C35 C41 C42 -131.4(13) . . . . ?
C44 C35 C41 C42 -7.1(14) . . . . ?
C35 C41 C42 C43 -1.7(17) . . . . ?
C41 C42 C43 O45 -111.7(19) . . . . ?
C41 C42 C43 O46 128.5(15) . . . . ?
C41 C42 C43 C44 10.3(13) . . . . ?
O45 C43 C44 C35 105.9(10) . . . . ?
O46 C43 C44 C35 -134.3(9) . . . . ?
C42 C43 C44 C35 -14.3(7) . . . . ?
C41 C35 C44 C43 13.6(8) . . . . ?
C34 C35 C44 C43 -103.8(9) . . . . ?
C36 C35 C44 C43 135.5(8) . . . . ?
O46 C43 O45 C47 -2.7(12) . . . . ?
C44 C43 O45 C47 119.2(12) . . . . ?
C42 C43 O45 C47 -126.0(15) . . . . ?
O45 C43 O46 C48 -20.2(13) . . . . ?
C44 C43 O46 C48 -144.5(12) . . . . ?
C42 C43 O46 C48 102.3(18) . . . . ?
C43 O45 C47 C48 22.2(14) . . . . ?
C43 O45 C47 C49 146.9(10) . . . . ?
C43 O46 C48 C47 34.5(13) . . . . ?
C43 O46 C48 C50 160.2(14) . . . . ?
O45 C47 C48 O46 -34.4(13) . . . . ?
C49 C47 C48 O46 -148.9(15) . . . . ?
O45 C47 C48 C50 -159.9(19) . . . . ?
C49 C47 C48 C50 86(2) . . . . ?

_refine_diff_density_max    0.263
_refine_diff_density_min   -0.301
_refine_diff_density_rms    0.070



_publ_section_references

;

Kabsch, W. (1988), J.Appl.Cryst 21 916-932.

Sheldrick, G.M. (1990) SHELX86, Acta Cryst. A46 467-480.

Sheldrick, G.M. (1993) SHELXL program for crystallography refinement.
University of Gottingen, Germany.

Spek, A.L., (1994) PLATON-94 program, Utrecht University, The 
Netherlands

;