fac-Trichloro­(pyrazolato)bis­(pyrazole)platinum(IV)

The title compound, [Pt(C₃H₃N₂)Cl₃(C₃H₄N₂)₂], has mirror symmetry. The Pt^IV atom has a slightly distorted octa­hedral geometry, with three facial Cl atoms and three N atoms, the latter from one pyrazolate (pz) and two pyrazole (pzH) ligands. There is an intra­molecular N—H...N...H—N hydrogen-bonding system, with N...N distances of 2.747 (7) Å.

Key indicators

• Single-crystal X-ray study
• T = 120 K
• Mean [sigma](C-C) = 0.009 Å
• R factor = 0.031
• wR factor = 0.081
• Data-to-parameter ratio = 16.3

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT342_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          9
PLAT480_ALERT_4_C Long H...A H-Bond Reported H2N    ..  N3      ..       2.71 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H2N    ..  CL1     ..       2.87 Ang.

Alert level G
ABSTM02_ALERT_3_G  The ratio of expected to reported Tmax/Tmin(RR) is > 1.10
            Tmin and Tmax reported:      0.189     0.631
            Tmin and Tmax expected:      0.145     0.590
            RR =      1.212
            Please check that your absorption correction is appropriate.

   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
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion

---

S1. Comment

Complexes containing various pyrazole ligands currently attract significant attention, due to their intrinsic biological, synthetic, catalytic and magnetic properties (Ardizzoia et al., 1991, 1994; Trofimenko, 1993; Sakai et al., 2000; Bigmore et al., 2005). During our ongoing studies of platinum complexes with N-donor ligands (Kukushkin & Pombeiro, 1999, 2002, 2005; Bokach & Kukushkin, 2005), the title complex, (I), was obtained as a by-product in the synthesis of cis-[PtCl₄(pzH)₂] by the known method of Minacheva et al. (2001) or as the target compound in the reaction described in the Experimental section. In this work, complex (I) has been characterized by X-ray crystallography, elemental analyses and ¹H NMR spectroscopy.

Complex (I) belongs to a class of octahedral platinum(IV) species bearing three Cl⁻ ligands in the fac arrangement (Fig. 1). The remaining coordination sites are occupied by one negatively charged pyrazolate (pz; N3/N4/C4–C6) and two neutral pyrazole ligands (pzH; N1/N2/C1–C3). The bond distances and angles in the heterocyclic rings are comparable with those previously reported for free pyrazole molecules (Berthou et al., 1970; Larsen et al., 1970; la Cour et al., 1973) and coordinated pyrazoles in cis-[PtCl₄(pzH)₂] (Minacheva et al., 2001; Khripun et al., 2005) and trans-[PtCl₄(pzH)₂] (Khripun et al., 2005).

An intramolecular N2—H2N···N4···H2Nⁱ—N2ⁱ hydrogen-bonding system is formed (Table 2). The N···N distances [2.747 (7) Å] are similar to those observed in fac-[Re(pz)(pzH)₂(CO)₃] [2.749 (7)–2.883 (6) Å; Ardizzoia et al., 1998]. Structurally characterized complexes with fac-M(pyrazole/ate)₃ moieties, resembling protonated or diprotonated tris(pyrazolyl)borates (Trofimenko, 1993), are known and include compounds with a fac-M(pz)₂(pzH) or fac-M(pz)(pzH)₂ structural unit, namely [Ir(η⁵-C₅Me₅)(pz)₂(pzH)] (Carmona et al., 1986), [Ru(η⁶-p-cymene)(pz)₂(pzH)] (p-cymene is 1-isopropyl-4-methylbenzene; Carmona et al., 1990), [Ru(η⁶-mesitylene)(pz)₂(pzH)] (Carmona et al., 1996), [Ru(η⁶-p-cymene)(pz)(pzH)₂][BF₄] (Carmona et al., 1990) and [Re(pz)(pzH)₂(CO)₃] (Ardizzoia et al., 1998). Thus, complex (I) represents the first example of a platinum complex of the fac-M(pyrazole/ate)₃ type and the second example of a structurally characterized complex with a fac-M(pz)(pzH)₂ hydrogen-bonding system. In [Ru(η⁶-p-cymene)(pz)(pzH)₂][BF₄] (Carmona et al., 1990), there is an intramolecular hydrogen bond between one of the pzH ligands and a pz anion, while the NH group of the second pzH ligand is involved in an intermolecular hydrogen bond with the counter-ion.

S2. Experimental

Compound (I) was obtained as a by-product in the synthesis of cis-[PtCl₄(pzH)₂] (Minacheva et al., 2001). A mixture of K₂[PtCl₆] (0.131 g, 0.27 mmol) and pzH (0.046 g, 0.68 mmol) was heated in water (Volume?) at 343 K for 30 min. The yellow solid which formed was collected by filtration, washed with one 5 ml portion of water and air-dried at room temperature. Under these conditions, a mixture of the target complex cis-[PtCl₄(pzH)₂] and complex (I) was formed (0.017 g; molar ratio of the products 2:1 by ¹H NMR integration). We also found that, when one more equivalent of pzH (0.018 g, 0.27 mmol) was added to the filtrate and the solution was further heated at 343 K for 10 h, a yellow precipitate of the title compound was formed. The solid was collected by filtration, washed with one 5 ml portion of water and air-dried at room temperature (yield 0.082 g, 60%, based on the starting K₂[PtCl₆]). Suitable crystals of (I) for X-ray study were obtained by slow evaporation of an acetone solution at room temperature. Analysis calculated for C₉H₁₁N₆Cl₃Pt: C 16.65, H 2.20, N 21.42%; found: C 16.55, H 2.22, N 21.50%; ¹H NMR (acetone-d₆, δ, p.p.m.): 6.56 (pseudo-t, J = 2.4 Hz, 1H, ⁴CH), 7.92 (d, J = 2.4 Hz, 1H, ⁵CH), 7.94 (d, J = 2.4 Hz, 1H, ³CH). It should be noted that, in the ¹H NMR spectrum, the equivalence of both pyrazole and pyrazolate ligands, on one hand, and the absence of signals from the NH protons, on the other hand, was observed, thus indicating for exchange processes in the solution.

S3. Refinement

The NH H atom (H2N) was located in a difference Fourier map and refined isotropically. Other H atoms were placed in idealized positions and constrained to ride on their parent atoms, with C—H = 0.95 Å and U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: COLLECT (Nonius, 2000); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SIR2002 (Burla et al., 2003); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 2005); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. A view of (I), with displacement ellipsoids drawn at the 50% probability level. Atoms N1A/N2A/Cl1A and unlabelled atoms are related to atoms N1/N2/Cl1 and other labelled atoms by the symmetry operation (x, 1/2 − y, z).

fac-Trichloro(pyrazolato)bis(pyrazole)platinum(IV)

Crystal data

[PtCl3(C3H3N2)(C3H4N2)2]	F(000) = 472
Mr = 504.68	Dx = 2.387 Mg m^−3
Monoclinic, P21/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yb	Cell parameters from 4975 reflections
a = 6.8307 (6) Å	θ = 3.0–27.4°
b = 13.5005 (7) Å	µ = 10.56 mm^−1
c = 7.6421 (7) Å	T = 120 K
β = 94.888 (3)°	Plate, yellow
V = 702.18 (10) Å^3	0.24 × 0.16 × 0.05 mm
Z = 2

Data collection

Nonius KappaCCD area-detector diffractometer	1645 independent reflections
Radiation source: fine-focus sealed tube	1522 reflections with I > 2σ(I)
Horizonally mounted graphite crystal monochromator	Rint = 0.044
Detector resolution: 9 pixels mm^-1	θmax = 27.4°, θmin = 3.0°
ϕ scans, and ω scans with κ offset	h = −8→7
Absorption correction: analytical (de Meulenaer & Tompa, 1965)	k = −17→14
Tmin = 0.189, Tmax = 0.631	l = −8→9
4975 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.031	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.081	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0542P)^2 + 1.4982P] where P = (Fo^2 + 2Fc^2)/3
1645 reflections	(Δ/σ)max = 0.002
101 parameters	Δρmax = 1.82 e Å^−3
0 restraints	Δρmin = −2.94 e Å^−3

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
Pt1	0.31554 (3)	0.2500	1.01373 (3)	0.01119 (12)
Cl1	0.49671 (18)	0.12879 (9)	0.89008 (18)	0.0156 (3)
Cl2	0.5399 (3)	0.2500	1.2607 (3)	0.0188 (4)
N1	0.1595 (6)	0.1404 (3)	1.1278 (6)	0.0123 (8)
N2	−0.0356 (6)	0.1266 (3)	1.0947 (6)	0.0150 (9)
H2N	−0.099 (10)	0.155 (5)	1.014 (9)	0.016 (16)*
N3	0.1260 (8)	0.2500	0.7924 (8)	0.0113 (12)
N4	−0.0686 (8)	0.2500	0.8079 (8)	0.0127 (12)
C1	−0.0928 (8)	0.0486 (4)	1.1857 (7)	0.0178 (11)
H1	−0.2229	0.0235	1.1843	0.021*
C2	0.0693 (8)	0.0115 (4)	1.2809 (8)	0.0191 (11)
H2	0.0742	−0.0439	1.3577	0.023*
C3	0.2252 (8)	0.0713 (4)	1.2424 (7)	0.0178 (11)
H3	0.3574	0.0642	1.2902	0.021*
C4	−0.1519 (10)	0.2500	0.6438 (10)	0.0147 (14)
H4	−0.2897	0.2500	0.6134	0.018*
C5	−0.0083 (11)	0.2500	0.5202 (10)	0.0165 (15)
H5	−0.0271	0.2500	0.3956	0.020*
C6	0.1685 (11)	0.2500	0.6281 (10)	0.0165 (15)
H6	0.2968	0.2500	0.5890	0.020*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pt1	0.00831 (17)	0.01220 (18)	0.01306 (18)	0.000	0.00093 (11)	0.000
Cl1	0.0118 (5)	0.0129 (6)	0.0224 (7)	0.0027 (4)	0.0035 (5)	−0.0013 (5)
Cl2	0.0134 (8)	0.0232 (9)	0.0187 (10)	0.000	−0.0040 (7)	0.000
N1	0.0101 (19)	0.012 (2)	0.015 (2)	0.0000 (15)	0.0015 (16)	0.0014 (17)
N2	0.014 (2)	0.017 (2)	0.014 (2)	−0.0010 (17)	0.0010 (18)	0.0014 (18)
N3	0.011 (3)	0.009 (3)	0.013 (3)	0.000	−0.004 (2)	0.000
N4	0.013 (3)	0.017 (3)	0.009 (3)	0.000	0.004 (2)	0.000
C1	0.022 (3)	0.015 (3)	0.018 (3)	−0.007 (2)	0.010 (2)	−0.001 (2)
C2	0.028 (3)	0.011 (2)	0.020 (3)	0.001 (2)	0.009 (2)	−0.002 (2)
C3	0.019 (2)	0.013 (2)	0.021 (3)	0.0032 (19)	0.001 (2)	0.002 (2)
C4	0.010 (3)	0.014 (3)	0.019 (4)	0.000	0.001 (3)	0.000
C5	0.021 (4)	0.018 (4)	0.011 (4)	0.000	0.004 (3)	0.000
C6	0.015 (3)	0.023 (4)	0.012 (4)	0.000	0.005 (3)	0.000

Geometric parameters (Å, º)

Pt1—N3	2.041 (6)	N4—C4	1.333 (10)
Pt1—N1	2.060 (4)	C1—C2	1.367 (8)
Pt1—N1^i	2.060 (4)	C1—H1	0.9500
Pt1—Cl1	2.3026 (12)	C2—C3	1.388 (7)
Pt1—Cl1^i	2.3026 (12)	C2—H2	0.9500
Pt1—Cl2	2.3274 (19)	C3—H3	0.9500
N1—C3	1.331 (7)	C4—C5	1.418 (10)
N1—N2	1.348 (6)	C4—H4	0.9500
N2—C1	1.339 (7)	C5—C6	1.403 (11)
N2—H2N	0.81 (7)	C5—H5	0.9500
N3—C6	1.312 (10)	C6—H6	0.9500
N3—N4	1.344 (8)
N3—Pt1—N1	92.07 (18)	C6—N3—Pt1	128.0 (5)
N3—Pt1—N1^i	92.07 (17)	N4—N3—Pt1	119.3 (5)
N1—Pt1—N1^i	91.8 (2)	C4—N4—N3	105.2 (6)
N3—Pt1—Cl1	89.14 (13)	N2—C1—C2	107.8 (5)
N1—Pt1—Cl1	88.78 (13)	N2—C1—H1	126.1
N1^i—Pt1—Cl1	178.62 (12)	C2—C1—H1	126.1
N3—Pt1—Cl1^i	89.14 (13)	C1—C2—C3	106.0 (5)
N1—Pt1—Cl1^i	178.62 (12)	C1—C2—H2	127.0
N1^i—Pt1—Cl1^i	88.77 (13)	C3—C2—H2	127.0
Cl1—Pt1—Cl1^i	90.59 (6)	N1—C3—C2	109.0 (5)
N3—Pt1—Cl2	178.21 (17)	N1—C3—H3	125.5
N1—Pt1—Cl2	89.18 (13)	C2—C3—H3	125.5
N1^i—Pt1—Cl2	89.18 (13)	N4—C4—C5	111.3 (6)
Cl1—Pt1—Cl2	89.60 (5)	N4—C4—H4	124.4
Cl1^i—Pt1—Cl2	89.60 (5)	C5—C4—H4	124.4
C3—N1—N2	107.4 (4)	C6—C5—C4	102.6 (7)
C3—N1—Pt1	128.6 (4)	C6—C5—H5	128.7
N2—N1—Pt1	124.0 (3)	C4—C5—H5	128.7
C1—N2—N1	109.8 (5)	N3—C6—C5	108.2 (6)
C1—N2—H2N	127 (5)	N3—C6—H6	125.9
N1—N2—H2N	122 (5)	C5—C6—H6	125.9
C6—N3—N4	112.7 (6)

Symmetry code: (i) x, −y+1/2, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2N···N4	0.81 (7)	2.06 (7)	2.747 (7)	142 (6)
N2—H2N···N3	0.81 (7)	2.71 (7)	3.125 (7)	114 (5)
N2—H2N···Cl1^ii	0.81 (7)	2.87 (7)	3.435 (5)	129 (6)

Symmetry code: (ii) x−1, y, z.