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Acta Cryst. (2008). E64, m575-m576    [ doi:10.1107/S1600536808007228 ]

Tetrachlorido(2,3-di-2-pyridylpyrazine-[kappa]2N1,N2)platinum(IV)

P. Delir Kheirollahi Nezhad, F. Azadbakht, V. Amani and H. R. Khavasi

Abstract top

In the title complex, [PtCl4(C14H10N4)], the PtIV atom is six-coordinated in an octahedral configuration by two N atoms from one 2,3-di-2-pyridylpyrazine ligand and four terminal Cl atoms. Intermolecular C-H...Cl and C-H...N hydrogen bonds stabilize the crystal structure.

Comment top

Amine platinum(IV) complexes have been known since the end of the last century (Hedin, 1886; Joergensen, 1900). Some of them have cancerostatic properties from which new interest aroused in these complexes (Bajusaz et al., 1989; Vorobevdesyatovskii et al., 1991). Due to the kinetic inertness of hexachloro-platinate(IV), cis- and trans-[PtC14L2] complexes (L=N, O, P, S donor ligand) were mainly prepared by oxidation reactions of the corresponding platinum(II) complexes [PtCl2L2] (Hedin, 1886; Joergensen, 1900).

Several PtIV complexes, with formula [PtCl4(N—N)], such as [PtCl4(bipyi)] (II) (Gaballa et al., 2003), [PtCl4(Me2bim)] (III) (Casas et al., 2005), [PtCl4(bipy)] (IV) (Hambley, 1986), [PtCl4(dcbipy)].H2O (V) (Hafizovic et al., 2006) and [PtCl4(dpk)] (VI) (Crowder et al., 2004) [where bipyi is 2,2'-bipyrimidinyl, Me2bim is 1,1'-dimethyl-2,2'-bi-imidazolyl, bipy is 2,2'-bipyridine, dcbipy is 2,2'-bipyridine-5,5'-dicarboxylic acid and dpk is bis(2-pyridyl)ketone] have been synthesized and characterized by single-crystal X-ray diffraction method.

There are also several PtIV complexes with formula [PtCl4L2], such as cis- and trans-[PtCl4(py)2] (VII) (Junicke et al., 1997), cis- and trans-[PtCl4(PzH)2] (VIII) (Khripun et al., 2006), trans-[PtCl4(NH3)2](1-Mu) (IX) (Witkowski et al., 1997), trans-[PtCl4(1-Prim)2] (X) (Kuduk-Jaworska et al., 1988), cis-[PtCl4(1-Etim)2] (XI) (Kuduk-Jaworska et al., 1990), trans-[PtCl4{NH=C(NMe2)OH}2] (XII) (Bokach et al., 2003), trans-[PtCl4{NH=C(Me)ON=CMe2}2] (XIII) (Kukushkin et al., 1998), cis-[PtCl4{NH=C(Et)N=CPh2}2] (XIV) (Garnovskii et al., 2001), trans- [PtCl4{NH=C(Et)ON=C(OH)Ph}2].2DMSO (XV) (Luzyanin, Kukushkin et al., 2002), trans-[PtCl4{NH=C(OMe)But}2] (XVI) (Gonzalez et al., 2002), trans-[PtCl4{NH=C(OH)Et}2] (XVII) (Luzyanin, Haukka et al., 2002) and trans- [PtCl4(pz)2] (XVIII) (Yousefi et al., 2007) [where PzH is pyrazole, 1-Mu is 1-methyluracil, 1-Prim is 1-propylimidazole 1-Etim is 1-ethylimidazoyl and Pz is pyrazine] have been synthesized and characterized by single-crystal X-ray diffraction method. We report herein the synthesis and crystal structure of the title compound.

In the mononuclear title compound (Fig. 1), the PtIV atom is six-coordinated in octahedral configuration by two N atoms from one 2,3-di-2-pyridylpyrazine ligand and four terminal Cl atoms. The Pt—Cl and Pt—N bond lengths and angles (Table 1) are in good agreement with the corresponding values in (II), (III) and (V).

In the crystal structure, intermolecular C—H···Cl and C—H···N hydrogen bonds (Table 2) seem to be effective in the stabilization of the crystal structure (Fig. 2).

Related literature top

For general background, see: Hedin (1886); Joergensen (1900); Bajusaz et al. (1989); Vorobevdesyatovskii et al. (1991). For related structures, see: Bokach et al. (2003); Casas et al. (2005); Crowder et al. (2004); Gaballa et al. (2003); Garnovskii et al. (2001); Gonzalez et al. (2002); Hafizovic et al. (2006); Hambley (1986); Kuduk-Jaworska et al. (1988, 1990); Junicke et al. (1997); Khripun et al. (2006); Kukushkin et al. (1998); Luzyanin, Haukka et al. (2002); Luzyanin, Kukushkin et al. (2002); Witkowski et al. (1997); Yousefi et al. (2007).

Experimental top

For the preparation of the title compound, a solution of 2,3-di-2-pyridylpyrazine (0.09 g, 0.37 mmol) in methanol (10 ml) was added to a solution of H2PtCl6.6H2O, (0.20 g, 0.37 mmol) in methanol (10 ml) at room temperature. The suitable crystals for X-ray diffraction experiment were obtained by methanol diffusion in a solution of orange precipitated in DMSO after one week (yield 0.18 g).

Refinement top

H atoms were positioned geometrically with C—H = 0.93 Å and constrained to ride on their parent atoms with Uiso(H)=1.2Ueq(C). The highest peak is 0.4 Å aprat from the Pt1 atom.

Computing details top

Data collection: X-AREA (Stoe & Cie, 2005); cell refinement: X-AREA (Stoe & Cie, 2005); data reduction: X-AREA (Stoe & Cie, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
[Figure 2] Fig. 2. A packing diagram for (I). Hydrogen bonds are shown as dashed lines.
Tetrachlorido(2,3-di-2-pyridylpyrazine-κ2N1,N2)platinum(IV) top
Crystal data top
[PtCl4(C14H10N4)]Dx = 2.331 Mg m−3
Mr = 571.14Melting point: 565-566 K K
Orthorhombic, P212121Mo Kα radiation
λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 1050 reflections
a = 6.6849 (4) Åθ = 1.9–29.2º
b = 14.9604 (12) ŵ = 9.28 mm−1
c = 16.2761 (10) ÅT = 120 (2) K
V = 1627.75 (19) Å3Block, orange
Z = 40.40 × 0.26 × 0.14 mm
F000 = 1072
Data collection top
Stoe IPDSII
diffractometer		4374 independent reflections
Radiation source: fine-focus sealed tube4327 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.064
Detector resolution: 0.15 mm pixels mm-1θmax = 29.2º
T = 120(2) Kθmin = 1.9º
rotation method scansh = −7→9
Absorption correction: Numerical
(X-SHAPE and X-RED; Stoe & Cie, 2005)		k = −20→17
Tmin = 0.070, Tmax = 0.270l = −22→22
9336 measured reflections
Refinement top
Refinement on F2H-atom parameters constrained
Least-squares matrix: full  w = 1/[σ2(Fo2) + (0.0439P)2 + 6.2735P]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.033(Δ/σ)max = 0.012
wR(F2) = 0.087Δρmax = 1.44 e Å−3
S = 1.10Δρmin = −1.82 e Å−3
4374 reflectionsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
209 parametersExtinction coefficient: 0.0011 (3)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), 1849 Friedel pairs
Secondary atom site location: difference Fourier mapFlack parameter: 0.005 (9)
Hydrogen site location: inferred from neighbouring sites
Crystal data top
[PtCl4(C14H10N4)]V = 1627.75 (19) Å3
Mr = 571.14Z = 4
Orthorhombic, P212121Mo Kα
a = 6.6849 (4) ŵ = 9.28 mm−1
b = 14.9604 (12) ÅT = 120 (2) K
c = 16.2761 (10) Å0.40 × 0.26 × 0.14 mm
Data collection top
Stoe IPDSII
diffractometer		4374 independent reflections
Absorption correction: Numerical
(X-SHAPE and X-RED; Stoe & Cie, 2005)		4327 reflections with I > 2σ(I)
Tmin = 0.070, Tmax = 0.270Rint = 0.064
9336 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.033H-atom parameters constrained
wR(F2) = 0.087Δρmax = 1.44 e Å−3
S = 1.10Δρmin = −1.82 e Å−3
4374 reflectionsAbsolute structure: Flack (1983), 1849 Friedel pairs
209 parametersFlack parameter: 0.005 (9)
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 > σ(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
C10.2795 (10)−0.5902 (5)−0.4681 (4)0.0286 (13)
H10.3170−0.6300−0.50920.034*
C20.3870 (11)−0.5866 (6)−0.3975 (4)0.0331 (15)
H20.4966−0.6241−0.39010.040*
C30.3330 (11)−0.5272 (6)−0.3366 (4)0.0331 (14)
H30.4084−0.5231−0.28870.040*
C40.1659 (10)−0.4738 (5)−0.3472 (4)0.0275 (12)
H40.1233−0.4358−0.30550.033*
C50.0622 (8)−0.4780 (4)−0.4217 (4)0.0221 (10)
C6−0.1195 (9)−0.4247 (4)−0.4420 (4)0.0218 (11)
C7−0.3997 (8)−0.4210 (5)−0.5265 (4)0.0245 (12)
H7−0.4677−0.4395−0.57330.029*
C8−0.4867 (9)−0.3598 (5)−0.4741 (5)0.0315 (14)
H8−0.6191−0.3433−0.48280.038*
C9−0.1996 (9)−0.3519 (4)−0.3978 (4)0.0244 (12)
C10−0.0817 (10)−0.2972 (4)−0.3392 (4)0.0262 (12)
C11−0.1610 (11)−0.2695 (5)−0.2651 (5)0.0314 (14)
H11−0.2912−0.2840−0.25000.038*
C12−0.0403 (15)−0.2197 (5)−0.2143 (5)0.0403 (17)
H12−0.0855−0.2024−0.16270.048*
C130.1475 (13)−0.1955 (5)−0.2404 (5)0.0372 (16)
H130.2293−0.1601−0.20750.045*
C140.2123 (12)−0.2246 (5)−0.3161 (6)0.0378 (17)
H140.3391−0.2073−0.33340.045*
Cl10.1281 (2)−0.41434 (11)−0.62538 (10)0.0272 (3)
Cl20.1441 (2)−0.63100 (12)−0.65809 (10)0.0299 (3)
Cl3−0.2674 (2)−0.52425 (12)−0.69333 (11)0.0312 (3)
Cl4−0.2288 (3)−0.65930 (12)−0.53083 (13)0.0338 (4)
N10.1199 (7)−0.5372 (4)−0.4799 (3)0.0236 (10)
N2−0.2178 (7)−0.4537 (4)−0.5100 (4)0.0240 (10)
N3−0.3883 (8)−0.3242 (4)−0.4123 (5)0.0299 (12)
N40.1041 (8)−0.2763 (4)−0.3664 (4)0.0301 (12)
Pt1−0.05541 (3)−0.537445 (15)−0.582177 (14)0.02145 (8)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.027 (3)0.033 (3)0.026 (3)0.013 (3)0.003 (3)0.001 (2)
C20.026 (3)0.046 (4)0.027 (3)0.005 (3)0.000 (3)0.004 (3)
C30.028 (3)0.044 (4)0.027 (3)−0.001 (3)−0.007 (3)0.005 (3)
C40.026 (3)0.037 (3)0.020 (3)0.001 (3)0.000 (2)0.002 (2)
C50.016 (2)0.030 (3)0.020 (2)−0.005 (2)0.003 (2)0.001 (2)
C60.018 (2)0.024 (3)0.023 (3)−0.004 (2)0.001 (2)0.001 (2)
C70.013 (2)0.029 (3)0.032 (3)−0.002 (2)0.000 (2)0.004 (2)
C80.017 (3)0.035 (3)0.043 (4)0.005 (2)0.001 (3)0.004 (3)
C90.021 (3)0.025 (3)0.027 (3)0.001 (2)0.002 (2)−0.002 (2)
C100.023 (3)0.027 (3)0.028 (3)0.004 (2)0.003 (2)0.003 (2)
C110.032 (3)0.029 (3)0.033 (3)0.002 (3)0.006 (3)−0.001 (3)
C120.057 (5)0.033 (3)0.031 (3)0.008 (4)−0.005 (4)−0.011 (3)
C130.039 (4)0.034 (4)0.038 (4)0.001 (3)−0.005 (3)−0.004 (3)
C140.034 (4)0.031 (4)0.049 (5)−0.005 (3)−0.004 (3)0.004 (3)
Cl10.0207 (6)0.0351 (8)0.0258 (7)−0.0030 (6)−0.0009 (6)0.0029 (6)
Cl20.0255 (7)0.0362 (8)0.0278 (7)0.0049 (6)0.0011 (6)−0.0056 (6)
Cl30.0239 (6)0.0386 (9)0.0312 (7)0.0024 (6)−0.0081 (6)−0.0064 (7)
Cl40.0282 (7)0.0296 (8)0.0437 (9)−0.0046 (6)0.0073 (7)−0.0032 (7)
N10.0149 (19)0.033 (3)0.022 (2)−0.002 (2)−0.0005 (17)0.003 (2)
N20.0113 (19)0.029 (3)0.031 (3)0.0035 (19)0.0002 (18)0.002 (2)
N30.019 (2)0.030 (3)0.040 (3)0.0024 (19)0.001 (2)−0.002 (3)
N40.025 (3)0.034 (3)0.031 (3)−0.007 (2)0.002 (2)0.001 (2)
Pt10.01531 (11)0.02622 (12)0.02281 (12)0.00055 (8)−0.00071 (8)−0.00174 (9)
Geometric parameters (Å, °) top
C1—N11.342 (8)C9—N31.349 (8)
C1—C21.357 (10)C9—C101.484 (9)
C1—H10.9300C10—N41.355 (9)
C2—C31.379 (11)C10—C111.382 (10)
C2—H20.9300C11—C121.373 (11)
C3—C41.385 (9)C11—H110.9300
C3—H30.9300C12—C131.374 (13)
C4—C51.398 (8)C12—H120.9300
C4—H40.9300C13—C141.377 (12)
C5—N11.353 (8)C13—H130.9300
C5—C61.490 (8)C14—N41.339 (10)
C6—N21.359 (8)C14—H140.9300
C6—C91.411 (9)Cl1—Pt12.3219 (16)
C7—N21.338 (7)Cl2—Pt12.2945 (16)
C7—C81.379 (10)Cl3—Pt12.3066 (16)
C7—H70.9300Cl4—Pt12.3164 (18)
C8—N31.315 (10)N1—Pt12.036 (5)
C8—H80.9300N2—Pt12.032 (6)
N1—C1—C2121.2 (7)C11—C12—C13119.6 (8)
N1—C1—H1119.4C11—C12—H12120.2
C2—C1—H1119.4C13—C12—H12120.2
C1—C2—C3119.7 (7)C12—C13—C14118.7 (8)
C1—C2—H2120.2C12—C13—H13120.6
C3—C2—H2120.2C14—C13—H13120.6
C2—C3—C4119.6 (7)N4—C14—C13124.1 (8)
C2—C3—H3120.2N4—C14—H14118.0
C4—C3—H3120.2C13—C14—H14118.0
C3—C4—C5118.8 (6)C1—N1—C5120.9 (6)
C3—C4—H4120.6C1—N1—Pt1125.0 (5)
C5—C4—H4120.6C5—N1—Pt1114.1 (4)
N1—C5—C4119.7 (6)C7—N2—C6119.1 (6)
N1—C5—C6115.3 (5)C7—N2—Pt1126.5 (5)
C4—C5—C6124.9 (6)C6—N2—Pt1114.2 (4)
N2—C6—C9118.6 (6)C8—N3—C9118.5 (6)
N2—C6—C5113.8 (5)C14—N4—C10115.4 (7)
C9—C6—C5127.6 (6)N2—Pt1—N180.4 (2)
N2—C7—C8120.1 (7)N2—Pt1—Cl2176.45 (16)
N2—C7—H7119.9N1—Pt1—Cl296.12 (17)
C8—C7—H7119.9N2—Pt1—Cl394.15 (16)
N3—C8—C7122.1 (6)N1—Pt1—Cl3174.20 (18)
N3—C8—H8119.0Cl2—Pt1—Cl389.26 (6)
C7—C8—H8119.0N2—Pt1—Cl490.54 (17)
N3—C9—C6120.2 (6)N1—Pt1—Cl489.68 (17)
N3—C9—C10116.1 (6)Cl2—Pt1—Cl490.30 (6)
C6—C9—C10123.5 (6)Cl3—Pt1—Cl492.45 (7)
N4—C10—C11124.6 (7)N2—Pt1—Cl188.17 (17)
N4—C10—C9113.8 (6)N1—Pt1—Cl186.68 (17)
C11—C10—C9121.5 (6)Cl2—Pt1—Cl190.78 (6)
C12—C11—C10117.6 (7)Cl3—Pt1—Cl191.11 (6)
C12—C11—H11121.2Cl4—Pt1—Cl1176.30 (7)
C10—C11—H11121.2
N1—C1—C2—C3−0.5 (12)C8—C7—N2—C6−1.0 (10)
C1—C2—C3—C42.0 (11)C8—C7—N2—Pt1−175.7 (5)
C2—C3—C4—C5−3.6 (10)C9—C6—N2—C7−9.1 (9)
C3—C4—C5—N13.6 (9)C5—C6—N2—C7169.0 (5)
C3—C4—C5—C6180.0 (6)C9—C6—N2—Pt1166.1 (5)
N1—C5—C6—N29.9 (8)C5—C6—N2—Pt1−15.7 (7)
C4—C5—C6—N2−166.6 (6)C7—C8—N3—C9−3.2 (11)
N1—C5—C6—C9−172.2 (6)C6—C9—N3—C8−7.3 (10)
C4—C5—C6—C911.3 (10)C10—C9—N3—C8167.8 (7)
N2—C7—C8—N37.7 (11)C13—C14—N4—C102.0 (11)
N2—C6—C9—N313.6 (10)C11—C10—N4—C14−0.5 (10)
C5—C6—C9—N3−164.2 (6)C9—C10—N4—C14178.0 (6)
N2—C6—C9—C10−161.1 (6)C7—N2—Pt1—N1−172.4 (6)
C5—C6—C9—C1021.1 (10)C6—N2—Pt1—N112.8 (5)
N3—C9—C10—N4−132.2 (7)C7—N2—Pt1—Cl39.7 (6)
C6—C9—C10—N442.7 (9)C6—N2—Pt1—Cl3−165.2 (4)
N3—C9—C10—C1146.4 (9)C7—N2—Pt1—Cl4−82.8 (5)
C6—C9—C10—C11−138.7 (7)C6—N2—Pt1—Cl4102.3 (4)
N4—C10—C11—C12−2.2 (11)C7—N2—Pt1—Cl1100.7 (5)
C9—C10—C11—C12179.4 (7)C6—N2—Pt1—Cl1−74.2 (4)
C10—C11—C12—C133.4 (11)C1—N1—Pt1—N2172.5 (6)
C11—C12—C13—C14−2.1 (12)C5—N1—Pt1—N2−7.1 (4)
C12—C13—C14—N4−0.7 (12)C1—N1—Pt1—Cl2−8.3 (6)
C2—C1—N1—C50.5 (11)C5—N1—Pt1—Cl2172.0 (4)
C2—C1—N1—Pt1−179.1 (6)C1—N1—Pt1—Cl481.9 (6)
C4—C5—N1—C1−2.1 (9)C5—N1—Pt1—Cl4−97.7 (4)
C6—C5—N1—C1−178.8 (6)C1—N1—Pt1—Cl1−98.8 (6)
C4—C5—N1—Pt1177.5 (5)C5—N1—Pt1—Cl181.6 (4)
C6—C5—N1—Pt10.8 (6)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C1—H1···Cl20.932.683.279 (7)122
C3—H3···Cl1i0.932.833.557 (7)136
C4—H4···N40.932.593.000 (10)107
C7—H7···Cl30.932.693.247 (7)120
C14—H14···Cl1ii0.932.743.599 (8)154
Symmetry codes: (i) −x+1/2, −y−1, z+1/2; (ii) x+1/2, −y−1/2, −z−1.
Table 1
Selected geometric parameters (Å, °) top
Cl1—Pt12.3219 (16)Cl4—Pt12.3164 (18)
Cl2—Pt12.2945 (16)N1—Pt12.036 (5)
Cl3—Pt12.3066 (16)N2—Pt12.032 (6)
N2—Pt1—N180.4 (2)Cl2—Pt1—Cl490.30 (6)
N2—Pt1—Cl2176.45 (16)Cl3—Pt1—Cl492.45 (7)
N1—Pt1—Cl296.12 (17)N2—Pt1—Cl188.17 (17)
N2—Pt1—Cl394.15 (16)N1—Pt1—Cl186.68 (17)
N1—Pt1—Cl3174.20 (18)Cl2—Pt1—Cl190.78 (6)
Cl2—Pt1—Cl389.26 (6)Cl3—Pt1—Cl191.11 (6)
N2—Pt1—Cl490.54 (17)Cl4—Pt1—Cl1176.30 (7)
N1—Pt1—Cl489.68 (17)
Table 2
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C1—H1···Cl20.932.683.279 (7)122
C3—H3···Cl1i0.932.833.557 (7)136
C4—H4···N40.932.593.000 (10)107
C7—H7···Cl30.932.693.247 (7)120
C14—H14···Cl1ii0.932.743.599 (8)154
Symmetry codes: (i) −x+1/2, −y−1, z+1/2; (ii) x+1/2, −y−1/2, −z−1.
Acknowledgements top

We are grateful to Payam Nor University for financial support.

references
References top

Bajusaz, S., Janaky, T., Csernus, V. J., Bokser, L., Fedeke, M., Srkalovic, G., Redding, T. W. & Schally, A. (1989). Proc. Natl Acad. Sci. USA, 86, 6313–6317.

Bokach, N. A., Pakhomova, T. B., Kukushkin, V. Y., Haukka, M. & Pombeiro, A. J. L. (2003). Inorg. Chem. 42, 7560–7568.

Casas, J. S., Castineiras, A., Parajo, Y., Sanchez, A., Gonzalez, A. S. & Sordo, J. (2005). Polyhedron, 24, 1196–1202.

Crowder, K. N., Garcia, S. J., Burr, R. L., North, J. M., Wilson, M. H., Conley, B. L., Fanwick, P. E., White, P. S., Sienerth, K. D. & Granger, R. M. (2004). Inorg. Chem. 43, 72–78.

Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.

Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.

Flack, H. D. (1983). Acta Cryst. A39, 876–881.

Gaballa, A., Wagner, C., Schmidt, H. & Steinborn, D. (2003). Z. Anorg. Allg. Chem. 629, 703–710.

Garnovskii, D. A., Kukushkin, V. Y., Haukka, M., Wagner, G. & Pombeiro, A. J. L. (2001). J. Chem. Soc. Dalton Trans. pp. 560–566.

Gonzalez, A. M., Cini, R., Intini, F. P., Pacifico, C. & Natile, G. (2002). Inorg. Chem. 41, 470–478.

Hafizovic, J., Olsbye, U. & Lillerud, K. P. (2006). Acta Cryst. E62, m414–m416.

Hambley, T. W. (1986). Acta Cryst. C42, 49–51.

Hedin, S. G. (1886). Acta Univ. Lund. 22, 1–6.

Kuduk-Jaworska, J., Kubiak, M. & Głowiak, T. (1988). Acta Cryst. C44, 437–439.

Kuduk-Jaworska, J., Kubiak, M., Głowiak, T. & Jeżowska-Trzebiatowska, B. (1990). Acta Cryst. C46, 2046–2049.

Joergensen, S. M. (1900). Z. Anorg. Chem. 25, 353–377.

Junicke, H., Schenzel, K., Heinemann, F. W., Pelz, K., Bogel, H. & Steinborn, D. (1997). Z. Anorg. Allg. Chem. 623, 603–607.

Khripun, A. V., Selivanov, S. I., Kukushkin, V. Y. & Haukka, M. (2006). Inorg. Chim. Acta, 359, 320–326.

Kukushkin, V. Y., Pakhomova, T. B., Kukushkin, Y. N., Herrmann, R., Wagner, G. & Pombeiro, A. J. L. (1998). Inorg. Chem. 37, 6511–6517.

Luzyanin, K. V., Haukka, M., Bokach, N. A., Kuznetsov, M. L., Kukushkin, V. Y. & Pombeiro, A. J. L. (2002). J. Chem. Soc. Dalton Trans. pp. 1882–1887.

Luzyanin, K. V., Kukushkin, V. Y., Kuznetsov, M. L., Garnovskii, D. A., Haukka, M. & Pombeiro, A. J. L. (2002). Inorg. Chem. 41, 2981–2986.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Stoe & Cie (2005). X-AREA, X-RED and X-SHAPE. Stoe & Cie, Darmstadt, Germany.

Vorobevdesyatovskii, N. V., Barinov, A. A., Lukin, Y. N., Sokolov, V. V., Demidov, V. N. & Kuptsov, A. Y. (1991). Zh. Obshch. Khim. 61, 709–716.

Witkowski, H., Freisinger, E. & Lippert, B. (1997). Chem. Commun. pp. 1315–1316.

Yousefi, M., Teimouri, S., Amani, V. & Khavasi, H. R. (2007). Acta Cryst. E63, m2869–m2870.