Tetra­chlorido(2,3-di-2-pyridylpyrazine-κ²N¹,N²)platinum(IV)

In the title complex, [PtCl₄(C₁₄H₁₀N₄)], the Pt^IV 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.

Key indicators

• Single-crystal X-ray study
• T = 120 K
• Mean [sigma](C-C) = 0.010 Å
• R factor = 0.033
• wR factor = 0.087
• Data-to-parameter ratio = 20.9

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT342_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...         10
PLAT432_ALERT_2_C Short Inter X...Y Contact  Cl2    ..  C13     ..       3.24 Ang.
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          1
              C14 H10 Cl4 N4 Pt

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           29.19
           From the CIF: _reflns_number_total               4374
           Count of symmetry unique reflns         2525
           Completeness (_total/calc)            173.23%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured      1849
           Fraction of Friedel pairs measured     0.732
           Are heavy atom types Z>Si present        yes

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 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
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

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 Pt^IV 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 Pt^IV 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)Bu^t}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 Pt^IV 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

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).

S2. Experimental

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).

S3. Refinement

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

Computing details

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

	Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. A packing diagram for (I). Hydrogen bonds are shown as dashed lines.

Tetrachlorido(2,3-di-2-pyridylpyrazine-κ²N¹,N²)platinum(IV)

Crystal data

[PtCl4(C14H10N4)]	Dx = 2.331 Mg m^−3
Mr = 571.14	Melting point: 565-566 K K
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 1050 reflections
a = 6.6849 (4) Å	θ = 1.9–29.2°
b = 14.9604 (12) Å	µ = 9.28 mm^−1
c = 16.2761 (10) Å	T = 120 K
V = 1627.75 (19) Å^3	Block, orange
Z = 4	0.40 × 0.26 × 0.14 mm
F(000) = 1072

Data collection

Stoe IPDSII diffractometer	4374 independent reflections
Radiation source: fine-focus sealed tube	4327 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.064
Detector resolution: 0.15 mm pixels mm^-1	θmax = 29.2°, θmin = 1.9°
rotation method scans	h = −7→9
Absorption correction: numerical (X-SHAPE and X-RED; Stoe & Cie, 2005)	k = −20→17
Tmin = 0.070, Tmax = 0.270	l = −22→22
9336 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.033	w = 1/[σ^2(Fo^2) + (0.0439P)^2 + 6.2735P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.087	(Δ/σ)max = 0.012
S = 1.10	Δρmax = 1.44 e Å^−3
4374 reflections	Δρmin = −1.82 e Å^−3
209 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0011 (3)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 1849 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.005 (9)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
C1	0.2795 (10)	−0.5902 (5)	−0.4681 (4)	0.0286 (13)
H1	0.3170	−0.6300	−0.5092	0.034*
C2	0.3870 (11)	−0.5866 (6)	−0.3975 (4)	0.0331 (15)
H2	0.4966	−0.6241	−0.3901	0.040*
C3	0.3330 (11)	−0.5272 (6)	−0.3366 (4)	0.0331 (14)
H3	0.4084	−0.5231	−0.2887	0.040*
C4	0.1659 (10)	−0.4738 (5)	−0.3472 (4)	0.0275 (12)
H4	0.1233	−0.4358	−0.3055	0.033*
C5	0.0622 (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	−0.5733	0.029*
C8	−0.4867 (9)	−0.3598 (5)	−0.4741 (5)	0.0315 (14)
H8	−0.6191	−0.3433	−0.4828	0.038*
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	−0.2500	0.038*
C12	−0.0403 (15)	−0.2197 (5)	−0.2143 (5)	0.0403 (17)
H12	−0.0855	−0.2024	−0.1627	0.048*
C13	0.1475 (13)	−0.1955 (5)	−0.2404 (5)	0.0372 (16)
H13	0.2293	−0.1601	−0.2075	0.045*
C14	0.2123 (12)	−0.2246 (5)	−0.3161 (6)	0.0378 (17)
H14	0.3391	−0.2073	−0.3334	0.045*
Cl1	0.1281 (2)	−0.41434 (11)	−0.62538 (10)	0.0272 (3)
Cl2	0.1441 (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)
N1	0.1199 (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)
N4	0.1041 (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 (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.027 (3)	0.033 (3)	0.026 (3)	0.013 (3)	0.003 (3)	0.001 (2)
C2	0.026 (3)	0.046 (4)	0.027 (3)	0.005 (3)	0.000 (3)	0.004 (3)
C3	0.028 (3)	0.044 (4)	0.027 (3)	−0.001 (3)	−0.007 (3)	0.005 (3)
C4	0.026 (3)	0.037 (3)	0.020 (3)	0.001 (3)	0.000 (2)	0.002 (2)
C5	0.016 (2)	0.030 (3)	0.020 (2)	−0.005 (2)	0.003 (2)	0.001 (2)
C6	0.018 (2)	0.024 (3)	0.023 (3)	−0.004 (2)	0.001 (2)	0.001 (2)
C7	0.013 (2)	0.029 (3)	0.032 (3)	−0.002 (2)	0.000 (2)	0.004 (2)
C8	0.017 (3)	0.035 (3)	0.043 (4)	0.005 (2)	0.001 (3)	0.004 (3)
C9	0.021 (3)	0.025 (3)	0.027 (3)	0.001 (2)	0.002 (2)	−0.002 (2)
C10	0.023 (3)	0.027 (3)	0.028 (3)	0.004 (2)	0.003 (2)	0.003 (2)
C11	0.032 (3)	0.029 (3)	0.033 (3)	0.002 (3)	0.006 (3)	−0.001 (3)
C12	0.057 (5)	0.033 (3)	0.031 (3)	0.008 (4)	−0.005 (4)	−0.011 (3)
C13	0.039 (4)	0.034 (4)	0.038 (4)	0.001 (3)	−0.005 (3)	−0.004 (3)
C14	0.034 (4)	0.031 (4)	0.049 (5)	−0.005 (3)	−0.004 (3)	0.004 (3)
Cl1	0.0207 (6)	0.0351 (8)	0.0258 (7)	−0.0030 (6)	−0.0009 (6)	0.0029 (6)
Cl2	0.0255 (7)	0.0362 (8)	0.0278 (7)	0.0049 (6)	0.0011 (6)	−0.0056 (6)
Cl3	0.0239 (6)	0.0386 (9)	0.0312 (7)	0.0024 (6)	−0.0081 (6)	−0.0064 (7)
Cl4	0.0282 (7)	0.0296 (8)	0.0437 (9)	−0.0046 (6)	0.0073 (7)	−0.0032 (7)
N1	0.0149 (19)	0.033 (3)	0.022 (2)	−0.002 (2)	−0.0005 (17)	0.003 (2)
N2	0.0113 (19)	0.029 (3)	0.031 (3)	0.0035 (19)	0.0002 (18)	0.002 (2)
N3	0.019 (2)	0.030 (3)	0.040 (3)	0.0024 (19)	0.001 (2)	−0.002 (3)
N4	0.025 (3)	0.034 (3)	0.031 (3)	−0.007 (2)	0.002 (2)	0.001 (2)
Pt1	0.01531 (11)	0.02622 (12)	0.02281 (12)	0.00055 (8)	−0.00071 (8)	−0.00174 (9)

Geometric parameters (Å, º)

C1—N1	1.342 (8)	C9—N3	1.349 (8)
C1—C2	1.357 (10)	C9—C10	1.484 (9)
C1—H1	0.9300	C10—N4	1.355 (9)
C2—C3	1.379 (11)	C10—C11	1.382 (10)
C2—H2	0.9300	C11—C12	1.373 (11)
C3—C4	1.385 (9)	C11—H11	0.9300
C3—H3	0.9300	C12—C13	1.374 (13)
C4—C5	1.398 (8)	C12—H12	0.9300
C4—H4	0.9300	C13—C14	1.377 (12)
C5—N1	1.353 (8)	C13—H13	0.9300
C5—C6	1.490 (8)	C14—N4	1.339 (10)
C6—N2	1.359 (8)	C14—H14	0.9300
C6—C9	1.411 (9)	Cl1—Pt1	2.3219 (16)
C7—N2	1.338 (7)	Cl2—Pt1	2.2945 (16)
C7—C8	1.379 (10)	Cl3—Pt1	2.3066 (16)
C7—H7	0.9300	Cl4—Pt1	2.3164 (18)
C8—N3	1.315 (10)	N1—Pt1	2.036 (5)
C8—H8	0.9300	N2—Pt1	2.032 (6)
N1—C1—C2	121.2 (7)	C11—C12—C13	119.6 (8)
N1—C1—H1	119.4	C11—C12—H12	120.2
C2—C1—H1	119.4	C13—C12—H12	120.2
C1—C2—C3	119.7 (7)	C12—C13—C14	118.7 (8)
C1—C2—H2	120.2	C12—C13—H13	120.6
C3—C2—H2	120.2	C14—C13—H13	120.6
C2—C3—C4	119.6 (7)	N4—C14—C13	124.1 (8)
C2—C3—H3	120.2	N4—C14—H14	118.0
C4—C3—H3	120.2	C13—C14—H14	118.0
C3—C4—C5	118.8 (6)	C1—N1—C5	120.9 (6)
C3—C4—H4	120.6	C1—N1—Pt1	125.0 (5)
C5—C4—H4	120.6	C5—N1—Pt1	114.1 (4)
N1—C5—C4	119.7 (6)	C7—N2—C6	119.1 (6)
N1—C5—C6	115.3 (5)	C7—N2—Pt1	126.5 (5)
C4—C5—C6	124.9 (6)	C6—N2—Pt1	114.2 (4)
N2—C6—C9	118.6 (6)	C8—N3—C9	118.5 (6)
N2—C6—C5	113.8 (5)	C14—N4—C10	115.4 (7)
C9—C6—C5	127.6 (6)	N2—Pt1—N1	80.4 (2)
N2—C7—C8	120.1 (7)	N2—Pt1—Cl2	176.45 (16)
N2—C7—H7	119.9	N1—Pt1—Cl2	96.12 (17)
C8—C7—H7	119.9	N2—Pt1—Cl3	94.15 (16)
N3—C8—C7	122.1 (6)	N1—Pt1—Cl3	174.20 (18)
N3—C8—H8	119.0	Cl2—Pt1—Cl3	89.26 (6)
C7—C8—H8	119.0	N2—Pt1—Cl4	90.54 (17)
N3—C9—C6	120.2 (6)	N1—Pt1—Cl4	89.68 (17)
N3—C9—C10	116.1 (6)	Cl2—Pt1—Cl4	90.30 (6)
C6—C9—C10	123.5 (6)	Cl3—Pt1—Cl4	92.45 (7)
N4—C10—C11	124.6 (7)	N2—Pt1—Cl1	88.17 (17)
N4—C10—C9	113.8 (6)	N1—Pt1—Cl1	86.68 (17)
C11—C10—C9	121.5 (6)	Cl2—Pt1—Cl1	90.78 (6)
C12—C11—C10	117.6 (7)	Cl3—Pt1—Cl1	91.11 (6)
C12—C11—H11	121.2	Cl4—Pt1—Cl1	176.30 (7)
C10—C11—H11	121.2
N1—C1—C2—C3	−0.5 (12)	C8—C7—N2—C6	−1.0 (10)
C1—C2—C3—C4	2.0 (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—N1	3.6 (9)	C5—C6—N2—C7	169.0 (5)
C3—C4—C5—C6	180.0 (6)	C9—C6—N2—Pt1	166.1 (5)
N1—C5—C6—N2	9.9 (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—C9	11.3 (10)	C10—C9—N3—C8	167.8 (7)
N2—C7—C8—N3	7.7 (11)	C13—C14—N4—C10	2.0 (11)
N2—C6—C9—N3	13.6 (10)	C11—C10—N4—C14	−0.5 (10)
C5—C6—C9—N3	−164.2 (6)	C9—C10—N4—C14	178.0 (6)
N2—C6—C9—C10	−161.1 (6)	C7—N2—Pt1—N1	−172.4 (6)
C5—C6—C9—C10	21.1 (10)	C6—N2—Pt1—N1	12.8 (5)
N3—C9—C10—N4	−132.2 (7)	C7—N2—Pt1—Cl3	9.7 (6)
C6—C9—C10—N4	42.7 (9)	C6—N2—Pt1—Cl3	−165.2 (4)
N3—C9—C10—C11	46.4 (9)	C7—N2—Pt1—Cl4	−82.8 (5)
C6—C9—C10—C11	−138.7 (7)	C6—N2—Pt1—Cl4	102.3 (4)
N4—C10—C11—C12	−2.2 (11)	C7—N2—Pt1—Cl1	100.7 (5)
C9—C10—C11—C12	179.4 (7)	C6—N2—Pt1—Cl1	−74.2 (4)
C10—C11—C12—C13	3.4 (11)	C1—N1—Pt1—N2	172.5 (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—C5	0.5 (11)	C5—N1—Pt1—Cl2	172.0 (4)
C2—C1—N1—Pt1	−179.1 (6)	C1—N1—Pt1—Cl4	81.9 (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—Pt1	177.5 (5)	C5—N1—Pt1—Cl1	81.6 (4)
C6—C5—N1—Pt1	0.8 (6)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···Cl2	0.93	2.68	3.279 (7)	122
C3—H3···Cl1^i	0.93	2.83	3.557 (7)	136
C4—H4···N4	0.93	2.59	3.000 (10)	107
C7—H7···Cl3	0.93	2.69	3.247 (7)	120
C14—H14···Cl1^ii	0.93	2.74	3.599 (8)	154

Symmetry codes: (i) −x+1/2, −y−1, z+1/2; (ii) x+1/2, −y−1/2, −z−1.