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Acta Cryst. (2007). E63, m2503-m2504    [ doi:10.1107/S1600536807042936 ]

(1,2-Disalicyloylhydrazine)hexakis(pyridine)dinickel(II) 1,2-disalicyloylhydrazine solvate

Y.-T. Chen, J.-M. Dou, D.-C. Li, D.-Q. Wang and Y.-H, Zhu

Abstract top

The title compound, [Ni2(C14H8N2O4)(C5H5N)6]C14H12N2O4, is composed of the complex [Ni2(C14H8N2O4)(C5H5N)6] and a free ligand. Each nickel(II) coordination environment in the complex exhibits a distorted octahedral geometry. The dinuclear complex is centrosymmetric. The complex molecules are linked into one-dimensional chains via intermolecular O-H...O hydrogen bonds.

Comment top

A large number of salicylhydrazine complexes have been prepared and studied. However, research on the complex with 1,2-disalicyloylhydrazine is limited to only one complex [Ni2(C14H8N2O4)(C5H5N)6]2C5H5N (Chen & Liu, 2005). We have synthesized another new complex [Ni2(C14H8N2O4)(C5H5N)6]C14H12N2O4, which has been characterized by X-ray diffraction and elemental analysis. Here we present the crystal structure of the title complex.

The title compound consists of the complex [Ni2(C14H8N2O4)(C5H5N)6] and a free ligand (1,2-disalicyloylhydrazine) (Fig. 1). The Ni complex is formed by one chelated ligand, two nickel ions and six pyridine molecules. The ligand is present as the tetranionic hexadentate ligand dsh4− and is linked with two nickel atoms. Both the binuclear nickel complex and the free ligand exhibit crystallographic centrosymmetry. From the data shown in Table 1, we can see that each nickel ion resides in a slightly distorted octahedral coordination environment, consisting of three pyridine N, a phenolate O, a carbonyl O and a hydrazine N of the ligand. which construct the fused five-membered and six-membered rings with each nickel atom. The two unique chelate rings, one five-membered and one six-membered, are near to coplanar with an 3.9 (3) ° dihedral angle.

As illustrated in Fig 2, the alternation of complex and free ligand molecules is linked into one-dimensional chain by intermolecular O4—H4···O2 H-bonds (Table 2) along the [1 − 1 1] axis.

Related literature top

The complex [Ni2(C14H8N2O4)(C5H5N)6]·2C5H5N with 1,2-disalicyloylhydrazine was reported previously (Chen & Liu, 2005). In that complex, the salicyloylhydrazine ligand functions as a tetranionic hexadentate ligand.

Experimental top

A solution of Ni(OAc)2H2O (0.0996 g, 0.4 mmol) in methanol (10 ml) was added to 1,2-disalicyloylhydrazine (0.054 g, 0.2 mmol) in pyridine (10 ml). After stirring the solution for four hours at room temperature, a reddish solution was obtained. After the solution had been standing for two weeks, red block crystals suitable for X-ray diffraction appeared. Yield: 0.086 g, 39%. m.p.> 573 K. Anal. for C58H50N10Ni2O8: Calc. C, 61.46; H, 4.41; N, 11.36; Found: C, 61.42; H, 4.47; N, 11.33%.

Refinement top

The H atoms on the ligands were allowed to ride on their parent atoms with C(sp2)—H distances of 0.93Å [Uiso(H)=1.2Ueq(C)] and C(phenyl)—H distances of 0.93Å [Uiso(H)=1.2Ueq(C)]. The O—H distance is 0.820Å [Uiso(H)=1.5Ueq(O)]. All non-hydrogen atoms were refined anisotropically.

Computing details top

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: SHELXTL (Sheldrick, 1997b).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title complex. Displacement ellipsoids are drawn at 30% probability level and H atoms have been omitted for clarity. symm. (A) −x + 1, −y + 2, −z, (B) −x, −y + 1, −z + 1
[Figure 2] Fig. 2. Crystal packing of the title complex.
(1,2-Disalicyloylhydrazine)hexakis(pyridine)dinickel(II) 1,2-disalicyloylhydrazine solvate top
Crystal data top
[Ni2(C14H8N2O4)(C5H5N)6]·C14H12N2O4Z = 1
Mr = 1132.50F000 = 588
Triclinic, P1Dx = 1.399 Mg m−3
a = 10.615 (4) ÅMo Kα radiation
λ = 0.71073 Å
b = 11.097 (4) ÅCell parameters from 2995 reflections
c = 12.094 (5) Åθ = 2.2–25.4º
α = 72.230 (4)ºµ = 0.77 mm−1
β = 85.285 (4)ºT = 298 (2) K
γ = 82.876 (4)ºBlock, red
V = 1344.7 (9) Å30.63 × 0.52 × 0.40 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer		4652 independent reflections
Radiation source: fine-focus sealed tube3642 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.024
T = 298(2) Kθmax = 25.0º
φ and ω scansθmin = 1.8º
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		h = −12→12
Tmin = 0.644, Tmax = 0.749k = −9→13
6973 measured reflectionsl = −13→14
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.035H-atom parameters constrained
wR(F2) = 0.102  w = 1/[σ2(Fo2) + (0.048P)2 + 0.4895P]
where P = (Fo2 + 2Fc2)/3
S = 1.00(Δ/σ)max = 0.001
4652 reflectionsΔρmax = 0.40 e Å−3
352 parametersΔρmin = −0.27 e Å−3
Primary atom site location: structure-invariant direct methodsExtinction correction: none
Crystal data top
[Ni2(C14H8N2O4)(C5H5N)6]·C14H12N2O4γ = 82.876 (4)º
Mr = 1132.50V = 1344.7 (9) Å3
Triclinic, P1Z = 1
a = 10.615 (4) ÅMo Kα
b = 11.097 (4) ŵ = 0.77 mm−1
c = 12.094 (5) ÅT = 298 (2) K
α = 72.230 (4)º0.63 × 0.52 × 0.40 mm
β = 85.285 (4)º
Data collection top
Bruker SMART CCD area-detector
diffractometer		4652 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		3642 reflections with I > 2σ(I)
Tmin = 0.644, Tmax = 0.749Rint = 0.024
6973 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.035352 parameters
wR(F2) = 0.102H-atom parameters constrained
S = 1.00Δρmax = 0.40 e Å−3
4652 reflectionsΔρmin = −0.27 e Å−3
Special details top

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

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R– factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Ni10.58655 (3)0.85566 (3)0.16798 (3)0.03193 (12)
N10.45229 (19)1.05133 (19)−0.00523 (17)0.0279 (5)
N20.7511 (2)0.9521 (2)0.16127 (19)0.0371 (5)
N30.5968 (2)0.7776 (2)0.34846 (18)0.0381 (5)
N40.4278 (2)0.7424 (2)0.18095 (19)0.0388 (5)
N50.0379 (3)0.5115 (3)0.5385 (2)0.0567 (7)
H50.07880.44950.58820.068*
O10.46160 (17)1.00370 (17)0.19156 (14)0.0366 (4)
O20.29489 (17)1.27700 (16)−0.11339 (15)0.0358 (4)
O3−0.0127 (2)0.7197 (2)0.4626 (2)0.0711 (7)
O40.1637 (2)0.43717 (19)0.73076 (18)0.0514 (5)
H40.20540.39130.78500.077*
C10.4151 (2)1.0710 (2)0.0945 (2)0.0285 (6)
C20.3100 (2)1.1727 (2)0.0950 (2)0.0306 (6)
C30.2541 (2)1.2639 (2)−0.0030 (2)0.0327 (6)
C40.1496 (3)1.3461 (3)0.0180 (3)0.0449 (7)
H4A0.11061.4054−0.04520.054*
C50.1028 (3)1.3425 (3)0.1281 (3)0.0528 (8)
H5A0.03291.39810.13810.063*
C60.1585 (3)1.2572 (3)0.2234 (3)0.0506 (8)
H60.12841.25580.29820.061*
C70.2595 (3)1.1742 (3)0.2060 (2)0.0419 (7)
H70.29651.11590.27080.050*
C80.8504 (3)0.8988 (3)0.2266 (3)0.0517 (8)
H80.84280.82170.28390.062*
C90.9626 (3)0.9511 (3)0.2139 (3)0.0656 (10)
H91.02850.91130.26270.079*
C100.9763 (3)1.0626 (3)0.1285 (3)0.0642 (10)
H101.05281.09870.11570.077*
C110.8747 (3)1.1202 (3)0.0620 (3)0.0642 (10)
H110.88011.19760.00460.077*
C120.7657 (3)1.0625 (3)0.0812 (3)0.0488 (8)
H120.69741.10280.03550.059*
C130.5915 (3)0.8589 (3)0.4115 (3)0.0541 (8)
H130.58390.94570.37300.065*
C140.5965 (4)0.8199 (4)0.5297 (3)0.0730 (11)
H140.59280.87920.57040.088*
C150.6072 (4)0.6928 (4)0.5873 (3)0.0803 (12)
H150.61170.66400.66770.096*
C160.6112 (4)0.6085 (4)0.5247 (3)0.0689 (10)
H160.61870.52130.56190.083*
C170.6040 (3)0.6544 (3)0.4060 (3)0.0485 (8)
H170.60420.59660.36420.058*
C180.3257 (3)0.7548 (3)0.2496 (3)0.0502 (8)
H180.32330.81240.29200.060*
C190.2233 (3)0.6862 (4)0.2606 (3)0.0644 (10)
H190.15340.69780.30940.077*
C200.2254 (4)0.6018 (4)0.2000 (4)0.0723 (11)
H200.15740.55430.20650.087*
C210.3297 (4)0.5875 (3)0.1286 (3)0.0666 (10)
H210.33370.53000.08610.080*
C220.4284 (3)0.6599 (3)0.1209 (3)0.0499 (8)
H220.49840.65060.07160.060*
C230.0469 (3)0.6322 (3)0.5347 (3)0.0493 (8)
C240.1349 (3)0.6538 (3)0.6131 (2)0.0451 (7)
C250.1928 (3)0.5585 (3)0.7058 (3)0.0442 (7)
C260.2772 (3)0.5909 (3)0.7717 (3)0.0585 (9)
H260.31580.52830.83300.070*
C270.3040 (4)0.7143 (4)0.7470 (4)0.0746 (11)
H270.36180.73470.79050.090*
C280.2452 (4)0.8086 (4)0.6577 (4)0.0819 (12)
H280.26190.89260.64220.098*
C290.1627 (4)0.7781 (3)0.5924 (3)0.0674 (10)
H290.12400.84220.53230.081*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ni10.0359 (2)0.0282 (2)0.02966 (19)0.00429 (14)−0.00713 (14)−0.00721 (14)
N10.0280 (11)0.0233 (11)0.0314 (11)0.0056 (8)−0.0071 (9)−0.0081 (9)
N20.0397 (13)0.0301 (12)0.0389 (12)0.0012 (10)−0.0122 (10)−0.0058 (10)
N30.0445 (14)0.0332 (13)0.0328 (12)−0.0011 (11)−0.0077 (10)−0.0040 (11)
N40.0379 (14)0.0361 (13)0.0397 (13)−0.0001 (10)−0.0056 (10)−0.0076 (11)
N50.0685 (19)0.0425 (15)0.0532 (16)0.0106 (14)−0.0261 (13)−0.0059 (13)
O10.0453 (11)0.0360 (10)0.0267 (9)0.0095 (8)−0.0078 (8)−0.0106 (8)
O20.0401 (11)0.0291 (10)0.0345 (10)0.0082 (8)−0.0055 (8)−0.0076 (8)
O30.0887 (19)0.0464 (14)0.0629 (15)0.0190 (13)−0.0272 (13)0.0024 (12)
O40.0591 (14)0.0373 (12)0.0513 (12)0.0072 (10)−0.0215 (10)−0.0036 (10)
C10.0285 (14)0.0281 (14)0.0303 (14)−0.0005 (11)−0.0041 (11)−0.0108 (11)
C20.0300 (14)0.0292 (14)0.0348 (14)−0.0016 (11)−0.0051 (11)−0.0125 (11)
C30.0321 (14)0.0283 (14)0.0387 (15)−0.0009 (11)−0.0028 (11)−0.0123 (12)
C40.0406 (17)0.0380 (17)0.0510 (18)0.0116 (13)−0.0040 (14)−0.0115 (14)
C50.0441 (18)0.0492 (19)0.064 (2)0.0144 (15)0.0028 (15)−0.0234 (17)
C60.0505 (19)0.057 (2)0.0478 (17)0.0094 (16)0.0045 (14)−0.0284 (16)
C70.0441 (17)0.0445 (17)0.0385 (15)0.0057 (14)−0.0060 (13)−0.0172 (14)
C80.0464 (19)0.0376 (17)0.063 (2)−0.0010 (14)−0.0196 (16)−0.0007 (15)
C90.048 (2)0.052 (2)0.091 (3)−0.0017 (17)−0.0284 (19)−0.007 (2)
C100.050 (2)0.062 (2)0.083 (3)−0.0165 (18)−0.0067 (18)−0.020 (2)
C110.074 (3)0.049 (2)0.062 (2)−0.0234 (19)−0.0175 (19)0.0038 (17)
C120.054 (2)0.0391 (17)0.0490 (18)−0.0059 (15)−0.0206 (15)−0.0022 (15)
C130.077 (2)0.0435 (18)0.0432 (17)0.0012 (16)−0.0187 (16)−0.0131 (15)
C140.105 (3)0.075 (3)0.0423 (19)0.002 (2)−0.0203 (19)−0.0234 (19)
C150.100 (3)0.096 (3)0.0348 (18)−0.010 (3)−0.0134 (19)−0.001 (2)
C160.081 (3)0.054 (2)0.054 (2)−0.009 (2)−0.0116 (19)0.0109 (19)
C170.0482 (19)0.0418 (18)0.0493 (18)−0.0016 (14)−0.0078 (14)−0.0041 (15)
C180.0499 (19)0.0480 (19)0.0465 (17)0.0000 (15)0.0034 (15)−0.0081 (15)
C190.050 (2)0.061 (2)0.067 (2)−0.0070 (18)0.0094 (17)0.0012 (19)
C200.056 (2)0.057 (2)0.095 (3)−0.0221 (19)−0.008 (2)−0.002 (2)
C210.071 (3)0.053 (2)0.084 (3)−0.0117 (19)−0.018 (2)−0.026 (2)
C220.0498 (19)0.0480 (19)0.0546 (18)−0.0010 (15)−0.0078 (15)−0.0195 (16)
C230.056 (2)0.0427 (18)0.0397 (16)0.0099 (15)0.0018 (14)−0.0052 (14)
C240.0491 (18)0.0384 (17)0.0428 (16)0.0048 (14)0.0024 (14)−0.0096 (14)
C250.0435 (17)0.0400 (17)0.0458 (17)0.0075 (14)0.0005 (13)−0.0130 (14)
C260.059 (2)0.054 (2)0.063 (2)0.0058 (17)−0.0104 (17)−0.0201 (18)
C270.077 (3)0.067 (3)0.092 (3)−0.008 (2)−0.011 (2)−0.040 (2)
C280.094 (3)0.049 (2)0.105 (3)−0.015 (2)−0.004 (3)−0.023 (2)
C290.084 (3)0.042 (2)0.069 (2)−0.0011 (18)−0.002 (2)−0.0088 (18)
Geometric parameters (Å, °) top
Ni1—N1i1.974 (2)C9—C101.364 (5)
Ni1—O2i2.0455 (18)C9—H90.9300
Ni1—O12.0549 (18)C10—C111.370 (5)
Ni1—N32.095 (2)C10—H100.9300
Ni1—N22.142 (2)C11—C121.360 (4)
Ni1—N42.192 (2)C11—H110.9300
N1—C11.312 (3)C12—H120.9300
N1—N1i1.410 (4)C13—C141.365 (4)
N1—Ni1i1.974 (2)C13—H130.9300
N2—C121.327 (3)C14—C151.365 (5)
N2—C81.335 (4)C14—H140.9300
N3—C171.328 (4)C15—C161.367 (5)
N3—C131.341 (4)C15—H150.9300
N4—C181.330 (4)C16—C171.374 (4)
N4—C221.331 (4)C16—H160.9300
N5—C231.341 (4)C17—H170.9300
N5—N5ii1.378 (5)C18—C191.378 (5)
N5—H50.8600C18—H180.9300
O1—C11.284 (3)C19—C201.352 (5)
O2—C31.339 (3)C19—H190.9300
O2—Ni1i2.0455 (18)C20—C211.370 (5)
O3—C231.235 (3)C20—H200.9300
O4—C251.356 (3)C21—C221.378 (4)
O4—H40.8200C21—H210.9300
C1—C21.485 (4)C22—H220.9300
C2—C71.409 (4)C23—C241.473 (4)
C2—C31.419 (4)C24—C291.389 (4)
C3—C41.404 (4)C24—C251.407 (4)
C4—C51.373 (4)C25—C261.394 (4)
C4—H4A0.9300C26—C271.370 (5)
C5—C61.372 (4)C26—H260.9300
C5—H5A0.9300C27—C281.382 (5)
C6—C71.371 (4)C27—H270.9300
C6—H60.9300C28—C291.362 (5)
C7—H70.9300C28—H280.9300
C8—C91.366 (4)C29—H290.9300
C8—H80.9300
N1i—Ni1—O2i90.10 (8)C9—C10—C11118.3 (3)
N1i—Ni1—O179.56 (8)C9—C10—H10120.8
O2i—Ni1—O1169.66 (7)C11—C10—H10120.8
N1i—Ni1—N3169.09 (8)C12—C11—C10119.1 (3)
O2i—Ni1—N3100.36 (8)C12—C11—H11120.5
O1—Ni1—N389.96 (8)C10—C11—H11120.5
N1i—Ni1—N293.18 (8)N2—C12—C11123.8 (3)
O2i—Ni1—N286.83 (8)N2—C12—H12118.1
O1—Ni1—N293.90 (9)C11—C12—H12118.1
N3—Ni1—N290.50 (9)N3—C13—C14123.0 (3)
N1i—Ni1—N489.88 (8)N3—C13—H13118.5
O2i—Ni1—N489.64 (8)C14—C13—H13118.5
O1—Ni1—N490.12 (9)C15—C14—C13119.1 (4)
N3—Ni1—N487.12 (9)C15—C14—H14120.5
N2—Ni1—N4175.33 (8)C13—C14—H14120.5
C1—N1—N1i113.2 (2)C14—C15—C16118.8 (3)
C1—N1—Ni1i133.30 (17)C14—C15—H15120.6
N1i—N1—Ni1i113.25 (19)C16—C15—H15120.6
C12—N2—C8116.2 (3)C15—C16—C17119.0 (3)
C12—N2—Ni1120.89 (18)C15—C16—H16120.5
C8—N2—Ni1122.46 (19)C17—C16—H16120.5
C17—N3—C13117.2 (3)N3—C17—C16122.9 (3)
C17—N3—Ni1125.4 (2)N3—C17—H17118.6
C13—N3—Ni1117.38 (19)C16—C17—H17118.6
C18—N4—C22117.2 (3)N4—C18—C19122.9 (3)
C18—N4—Ni1120.6 (2)N4—C18—H18118.6
C22—N4—Ni1122.2 (2)C19—C18—H18118.6
C23—N5—N5ii119.0 (3)C20—C19—C18119.4 (3)
C23—N5—H5120.5C20—C19—H19120.3
N5ii—N5—H5120.5C18—C19—H19120.3
C1—O1—Ni1110.36 (15)C19—C20—C21118.8 (3)
C3—O2—Ni1i124.83 (16)C19—C20—H20120.6
C25—O4—H4109.5C21—C20—H20120.6
O1—C1—N1123.2 (2)C20—C21—C22118.9 (3)
O1—C1—C2118.8 (2)C20—C21—H21120.5
N1—C1—C2118.0 (2)C22—C21—H21120.5
C7—C2—C3117.7 (2)N4—C22—C21122.8 (3)
C7—C2—C1115.1 (2)N4—C22—H22118.6
C3—C2—C1127.3 (2)C21—C22—H22118.6
O2—C3—C4118.1 (2)O3—C23—N5119.3 (3)
O2—C3—C2124.4 (2)O3—C23—C24123.0 (3)
C4—C3—C2117.5 (2)N5—C23—C24117.5 (3)
C5—C4—C3122.5 (3)C29—C24—C25118.2 (3)
C5—C4—H4A118.7C29—C24—C23116.8 (3)
C3—C4—H4A118.7C25—C24—C23125.0 (3)
C6—C5—C4120.5 (3)O4—C25—C26121.1 (3)
C6—C5—H5A119.8O4—C25—C24119.5 (3)
C4—C5—H5A119.8C26—C25—C24119.4 (3)
C7—C6—C5118.5 (3)C27—C26—C25120.5 (3)
C7—C6—H6120.8C27—C26—H26119.7
C5—C6—H6120.8C25—C26—H26119.7
C6—C7—C2123.4 (3)C26—C27—C28120.2 (4)
C6—C7—H7118.3C26—C27—H27119.9
C2—C7—H7118.3C28—C27—H27119.9
N2—C8—C9123.7 (3)C29—C28—C27119.8 (4)
N2—C8—H8118.1C29—C28—H28120.1
C9—C8—H8118.1C27—C28—H28120.1
C10—C9—C8118.9 (3)C28—C29—C24121.8 (4)
C10—C9—H9120.6C28—C29—H29119.1
C8—C9—H9120.6C24—C29—H29119.1
Symmetry codes: (i) −x+1, −y+2, −z; (ii) −x, −y+1, −z+1.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O4—H4···O2iii0.821.722.534 (3)171
Symmetry codes: (iii) x, y−1, z+1.
Selected geometric parameters (°) top
N1i—Ni1—O2i90.10 (8)O1—Ni1—N293.90 (9)
N1i—Ni1—O179.56 (8)N3—Ni1—N290.50 (9)
O2i—Ni1—O1169.66 (7)N1i—Ni1—N489.88 (8)
N1i—Ni1—N3169.09 (8)O2i—Ni1—N489.64 (8)
O2i—Ni1—N3100.36 (8)O1—Ni1—N490.12 (9)
O1—Ni1—N389.96 (8)N3—Ni1—N487.12 (9)
N1i—Ni1—N293.18 (8)N2—Ni1—N4175.33 (8)
O2i—Ni1—N286.83 (8)
Symmetry codes: (i) −x+1, −y+2, −z.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O4—H4···O2ii0.821.722.534 (3)171
Symmetry codes: (ii) x, y−1, z+1.
Acknowledgements top

The authors acknowledge the support of the National Natural Science Foundation of China (20671048).

references
References top

Chen, X. H. & Liu, S. X. (2005). Chin. J. Inorg. Chem. 21, 15–20.

Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.

Sheldrick, G. M. (1997a). SHELXL97 and SHELXS97. University of Göttingen, Germany.

Sheldrick, G. M. (1997b). SHELXTL. Version 5.1 Software Reference Manual. Bruker AXS Inc., Madison, Wisconsin, USA.

Siemens (1996). SMART and SAINT. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA.