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The molecule of the title compound, [PtCl4(C4H4N2)2], possesses mmm symmetry. The PtIVatom is six-coordinated in an octa­hedral configuration by two N atoms of two pyrazine rings and four Cl atoms. In the crystal structure, there are π–π inter­actions between the pyrazine rings [the closest distance between adjacent rings is 3.6485 (7) Å].

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807052555/hk2345sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807052555/hk2345Isup2.hkl
Contains datablock I

CCDC reference: 669126

Key indicators

  • Single-crystal X-ray study
  • T = 120 K
  • Mean [sigma](C-C) = 0.009 Å
  • R factor = 0.053
  • wR factor = 0.154
  • Data-to-parameter ratio = 17.6

checkCIF/PLATON results

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Alert level C PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical . ? PLAT342_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ... 9
Alert level G PLAT794_ALERT_5_G Check Predicted Bond Valency for Pt1 (2) 2.99
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 2 ALERT level C = Check and explain 1 ALERT level G = General alerts; check 1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 0 ALERT type 2 Indicator that the structure model may be wrong or deficient 1 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion 1 ALERT type 5 Informative message, check

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-[PtCl4L2] complexes (L = N, O, P, S donor ligands) were mainly prepared by oxidation reactions of the corresponding platinum(II) complexes [PtCl2L2], (Hedin, 1886; Joergensen, 1900). Several PtIV complexes, with formula, [PtCl4L2], such as cis- and trans-[PtCl4– (py)2], (II), (Junicke et al., 1997), cis- and trans-[PtCl4(PzH)2], (III), (Khripun et al., 2006), trans-[PtCl4(NH3)2](1-Mu), (IV), (Witkowski et al., 1997), trans-[PtCl4(1-Prim)2], (V), (Kuduk-Jaworska et al., 1988), cis-[PtCl4(1-Etim)2], (VI), (Kuduk-Jaworska et al., 1990), trans-[PtCl4{NH=C(NMe2)OH}2], (VII), (Bokach et al., 2003), trans-[PtCl4{NH=C(Me)ON=CMe2}2], (VIII), (Kukushkin et al., 1998), cis-[PtCl4{NH=C(Et)N=CPh2}2], (IX), (Garnovskii et al., 2001), trans-[PtCl4{NH=C(Et)ON=C(OH)Ph}2].2DMSO, (X), (Luzyanin, Kukushkin et al., 2002), trans-[PtCl4{NH=C(OMe)But}2], (XI), (Gonzalez et al., 2002) and trans-[PtCl4{NH=C(OH)Et}2], (XII), (Luzyanin, Haukka et al., 2002) [where PzH is pyrazole, 1-Mu is 1-methyluracil, 1-Prim is 1-propylimidazole and 1-Etim is 1-ethylimidazoyl] have been synthesized and characterized by single-crystal X-ray diffraction methods.

There are also several PtIV complexes, with formula, [PtCl4(N—N)], such as [PtCl4(bipyi)], (XIII), (Gaballa et al., 2003), [PtCl4(Me2bim)], (XIV), (Casas et al., 2005), [PtCl4(bipy)], (XV), (Hambley, 1986), [PtCl4(dcbipy)].H2O, (XVI), (Hafizovic et al., 2006) and [PtCl4(dpk)], (XVII), (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 methods. We report herein the synthesis and crystal structure of the title compound, (I).

The asymmetric unit of (I), (Fig. 1), contains one pyrazine and one chlorido- platinate ligands. The PtIVatom is six-coordinated in octahedral configuration by two N atoms of two pyrazine and four Cl atoms of tetrachloridoplatinate ligands. The Pt—Cl and Pt—N bond lengths and angles (Table 1) are in good agreement with the corresponding values in (II) and (VI).

In the crystal structure (Fig. 2), there are some π-π interactions between the pyrazine rings, in which they may be effective in the stabilization of the structure. The distance between the adjacent rings is 3.6485 (7) Å [symmetry codes: -1/2 - x, y, 1/2 - z; 1/2 - x, y, 1/2 - z; -1/2 + x, y, 1/2 - z; 1/2 + x, y, 1/2 - z].

Related literature top

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

Experimental top

For the preparation of the title compound, (I), a solution of pyrazine (60 mg, 0.74 mmol) in methanol (10 ml) was added to a solution of H2PtCl6.2H2O (200 mg, 0.37 mmol) in methanol (10 ml) at room temperature. The suitable crystals for X-ray analysis were obtained by methanol diffusion in a solution of the yellow precipitate in DMSO, after one week (yield; 150 mg, 81.6%).

Refinement top

H atoms were positioned geometrically, with C—H = 0.93 Å, for aromatic H atoms and constrained to ride on their parent atoms, with Uiso(H) = 1.2Ueq(C).

Structure description 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-[PtCl4L2] complexes (L = N, O, P, S donor ligands) were mainly prepared by oxidation reactions of the corresponding platinum(II) complexes [PtCl2L2], (Hedin, 1886; Joergensen, 1900). Several PtIV complexes, with formula, [PtCl4L2], such as cis- and trans-[PtCl4– (py)2], (II), (Junicke et al., 1997), cis- and trans-[PtCl4(PzH)2], (III), (Khripun et al., 2006), trans-[PtCl4(NH3)2](1-Mu), (IV), (Witkowski et al., 1997), trans-[PtCl4(1-Prim)2], (V), (Kuduk-Jaworska et al., 1988), cis-[PtCl4(1-Etim)2], (VI), (Kuduk-Jaworska et al., 1990), trans-[PtCl4{NH=C(NMe2)OH}2], (VII), (Bokach et al., 2003), trans-[PtCl4{NH=C(Me)ON=CMe2}2], (VIII), (Kukushkin et al., 1998), cis-[PtCl4{NH=C(Et)N=CPh2}2], (IX), (Garnovskii et al., 2001), trans-[PtCl4{NH=C(Et)ON=C(OH)Ph}2].2DMSO, (X), (Luzyanin, Kukushkin et al., 2002), trans-[PtCl4{NH=C(OMe)But}2], (XI), (Gonzalez et al., 2002) and trans-[PtCl4{NH=C(OH)Et}2], (XII), (Luzyanin, Haukka et al., 2002) [where PzH is pyrazole, 1-Mu is 1-methyluracil, 1-Prim is 1-propylimidazole and 1-Etim is 1-ethylimidazoyl] have been synthesized and characterized by single-crystal X-ray diffraction methods.

There are also several PtIV complexes, with formula, [PtCl4(N—N)], such as [PtCl4(bipyi)], (XIII), (Gaballa et al., 2003), [PtCl4(Me2bim)], (XIV), (Casas et al., 2005), [PtCl4(bipy)], (XV), (Hambley, 1986), [PtCl4(dcbipy)].H2O, (XVI), (Hafizovic et al., 2006) and [PtCl4(dpk)], (XVII), (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 methods. We report herein the synthesis and crystal structure of the title compound, (I).

The asymmetric unit of (I), (Fig. 1), contains one pyrazine and one chlorido- platinate ligands. The PtIVatom is six-coordinated in octahedral configuration by two N atoms of two pyrazine and four Cl atoms of tetrachloridoplatinate ligands. The Pt—Cl and Pt—N bond lengths and angles (Table 1) are in good agreement with the corresponding values in (II) and (VI).

In the crystal structure (Fig. 2), there are some π-π interactions between the pyrazine rings, in which they may be effective in the stabilization of the structure. The distance between the adjacent rings is 3.6485 (7) Å [symmetry codes: -1/2 - x, y, 1/2 - z; 1/2 - x, y, 1/2 - z; -1/2 + x, y, 1/2 - z; 1/2 + x, y, 1/2 - z].

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

Computing details top

Data collection: X-AREA (Stoe & Cie, 2005); cell refinement: X-AREA (Stoe & Cie, 2005); data reduction: X-RED (Stoe & Cie, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); 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 [symmetry codes: (a) -x, -y, -z; (b) x, -y, -z; (c) -x, y, z].
[Figure 2] Fig. 2. A packing diagram of (I).
trans-Tetrachloridobis(pyrazine-κN)platinum(IV) top
Crystal data top
[PtCl4(C4H4N2)2]F(000) = 920
Mr = 497.06Dx = 2.643 Mg m3
Orthorhombic, CmcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2bc 2Cell parameters from 2500 reflections
a = 7.2107 (7) Åθ = 3.3–29.2°
b = 14.6318 (18) ŵ = 12.07 mm1
c = 11.8392 (11) ÅT = 120 K
V = 1249.1 (2) Å3Plate, yellow
Z = 40.25 × 0.25 × 0.08 mm
Data collection top
Stoe IPDSII
diffractometer
898 independent reflections
Radiation source: fine-focus sealed tube883 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.099
Detector resolution: 0.15 mm pixels mm-1θmax = 29.2°, θmin = 3.3°
rotation method scansh = 99
Absorption correction: numerical
[shape of crystal determined optically (X-RED; Stoe & Cie, 2005)]
k = 2020
Tmin = 0.070, Tmax = 0.380l = 1616
6750 measured reflections
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)] = 0.053H-atom parameters constrained
wR(F2) = 0.154 w = 1/[σ2(Fo2) + (0.0791P)2 + 1.5933P]
where P = (Fo2 + 2Fc2)/3
S = 1.38(Δ/σ)max = 0.004
898 reflectionsΔρmax = 4.88 e Å3
51 parametersΔρmin = 3.22 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0156 (16)
Crystal data top
[PtCl4(C4H4N2)2]V = 1249.1 (2) Å3
Mr = 497.06Z = 4
Orthorhombic, CmcaMo Kα radiation
a = 7.2107 (7) ŵ = 12.07 mm1
b = 14.6318 (18) ÅT = 120 K
c = 11.8392 (11) Å0.25 × 0.25 × 0.08 mm
Data collection top
Stoe IPDSII
diffractometer
898 independent reflections
Absorption correction: numerical
[shape of crystal determined optically (X-RED; Stoe & Cie, 2005)]
883 reflections with I > 2σ(I)
Tmin = 0.070, Tmax = 0.380Rint = 0.099
6750 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0530 restraints
wR(F2) = 0.154H-atom parameters constrained
S = 1.38Δρmax = 4.88 e Å3
898 reflectionsΔρmin = 3.22 e Å3
51 parameters
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
Pt10.00000.00000.00000.0186 (4)
Cl10.22812 (15)0.08739 (7)0.08595 (9)0.0236 (4)
N10.00000.0885 (3)0.1339 (4)0.0219 (11)
N20.00000.2037 (4)0.3202 (5)0.0284 (12)
C10.00000.1797 (4)0.1203 (5)0.0242 (12)
H10.00000.20500.04820.029*
C20.00000.2356 (5)0.2146 (6)0.0266 (13)
H20.00000.29850.20390.032*
C30.00000.1117 (4)0.3307 (6)0.0254 (12)
H30.00000.08630.40270.030*
C40.00000.0545 (4)0.2386 (5)0.0237 (12)
H40.00000.00850.24930.028*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Pt10.0162 (4)0.0201 (5)0.0194 (5)0.0000.0000.00249 (8)
Cl10.0211 (6)0.0257 (7)0.0239 (7)0.0031 (3)0.0027 (3)0.0028 (4)
N10.016 (2)0.026 (2)0.024 (3)0.0000.0000.0021 (19)
N20.026 (2)0.031 (3)0.028 (3)0.0000.0000.005 (2)
C10.021 (2)0.024 (3)0.029 (3)0.0000.0000.004 (2)
C20.025 (3)0.024 (3)0.031 (4)0.0000.0000.004 (3)
C30.023 (3)0.027 (3)0.026 (3)0.0000.0000.002 (3)
C40.022 (2)0.023 (3)0.026 (3)0.0000.0000.003 (2)
Geometric parameters (Å, º) top
Pt1—Cl1i2.3186 (10)C1—H10.9300
Pt1—Cl12.3186 (10)C2—N21.335 (8)
Pt1—Cl1ii2.3186 (10)C2—H20.9300
Pt1—Cl1iii2.3186 (10)C3—N21.352 (8)
N1—Pt12.047 (5)C3—C41.375 (9)
Pt1—N1i2.047 (5)C3—H30.9300
C1—N11.344 (7)C4—N11.336 (8)
C1—C21.384 (9)C4—H40.9300
Cl1i—Pt1—Cl1ii90.38 (5)N1—C1—H1120.3
Cl1—Pt1—Cl1ii89.62 (5)C2—C1—H1120.3
Cl1i—Pt1—Cl1iii89.62 (5)N2—C2—C1123.3 (6)
Cl1—Pt1—Cl1iii90.38 (5)N2—C2—H2118.3
Cl1ii—Pt1—Cl1iii180C1—C2—H2118.3
N1—Pt1—Cl1i89.48 (10)N2—C3—C4122.3 (6)
N1i—Pt1—Cl1i90.52 (10)N2—C3—H3118.9
N1—Pt1—Cl190.52 (10)C4—C3—H3118.9
N1i—Pt1—Cl189.48 (10)N1—C4—C3120.6 (6)
Cl1i—Pt1—Cl1180N1—C4—H4119.7
N1—Pt1—Cl1ii89.48 (10)C3—C4—H4119.7
N1i—Pt1—Cl1ii90.52 (10)C4—N1—C1118.8 (6)
N1—Pt1—N1i180C4—N1—Pt1118.9 (4)
N1—Pt1—Cl1iii90.52 (10)C1—N1—Pt1122.4 (4)
N1i—Pt1—Cl1iii89.48 (10)C2—N2—C3115.7 (6)
N1—C1—C2119.3 (6)
C4—N1—Pt1—Cl1i134.81 (3)N1—C1—C2—N20.0
C1—N1—Pt1—Cl1i45.19 (3)N2—C3—C4—N10.0
C4—N1—Pt1—Cl145.19 (3)C3—C4—N1—C10.0
C1—N1—Pt1—Cl1134.81 (3)C3—C4—N1—Pt1180.0
C4—N1—Pt1—Cl1ii134.81 (3)C2—C1—N1—C40.0
C1—N1—Pt1—Cl1ii45.19 (3)C2—C1—N1—Pt1180.0
C4—N1—Pt1—Cl1iii45.19 (3)C1—C2—N2—C30.0
C1—N1—Pt1—Cl1iii134.81 (3)C4—C3—N2—C20.0
Symmetry codes: (i) x, y, z; (ii) x, y, z; (iii) x, y, z.

Experimental details

Crystal data
Chemical formula[PtCl4(C4H4N2)2]
Mr497.06
Crystal system, space groupOrthorhombic, Cmca
Temperature (K)120
a, b, c (Å)7.2107 (7), 14.6318 (18), 11.8392 (11)
V3)1249.1 (2)
Z4
Radiation typeMo Kα
µ (mm1)12.07
Crystal size (mm)0.25 × 0.25 × 0.08
Data collection
DiffractometerStoe IPDSII
Absorption correctionNumerical
[shape of crystal determined optically (X-RED; Stoe & Cie, 2005)]
Tmin, Tmax0.070, 0.380
No. of measured, independent and
observed [I > 2σ(I)] reflections
6750, 898, 883
Rint0.099
(sin θ/λ)max1)0.686
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.053, 0.154, 1.38
No. of reflections898
No. of parameters51
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)4.88, 3.22

Computer programs: X-AREA (Stoe & Cie, 2005), X-RED (Stoe & Cie, 2005), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Selected geometric parameters (Å, º) top
Pt1—Cl12.3186 (10)N1—Pt12.047 (5)
Cl1i—Pt1—Cl1ii90.38 (5)N1—Pt1—Cl190.52 (10)
Cl1—Pt1—Cl1ii89.62 (5)Cl1i—Pt1—Cl1180
Cl1ii—Pt1—Cl1iii180N1—Pt1—N1i180
N1—Pt1—Cl1i89.48 (10)
Symmetry codes: (i) x, y, z; (ii) x, y, z; (iii) x, y, z.
 

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