Dichlorido-1κ²Cl-μ-[(1,2,5,6-η:3,4,7,8-η)-1,3,5,7-cyclo­octa­tetra­ene]dimethyl-2κ²C-diplatinum(II)

The title complex, [Pt₂(CH₃)₂Cl₂(C₈H₈)], consists of PtCl₂ and Pt(CH₃)₂ groups bridged by a 1,3,5,7-cyclo­octa­tetra­ene ligand, and is disposed about a mirror plane passing through the two Pt atoms, the methyl groups and the centre of the ligand. The coordination geometry around each Pt^II centre is essentially square planar.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.020 Å
• R factor = 0.058
• wR factor = 0.145
• Data-to-parameter ratio = 19.5

checkCIF/PLATON results

No syntax errors found



Alert level C
ABSTM02_ALERT_3_C  The ratio of expected to reported Tmax/Tmin(RR) is > 1.10
            Tmin and Tmax reported:      0.574     1.000
            Tmin and Tmax expected:      0.051     0.105
            RR =      1.183
            Please check that your absorption correction is appropriate.
PLAT060_ALERT_3_C Ratio Tmax/Tmin (Exp-to-Rep) (too) Large .......       1.24
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.10
PLAT342_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...         20
PLAT733_ALERT_1_C Torsion Calc    -91.3(9), Rep    -91.2(2) ......       4.50 su-Ra
              C6  -PT2 -C3  -C3     1.555   1.555   1.555   7.575

Alert level G
ABSTM02_ALERT_3_G  When printed, the submitted absorption T values will be
            replaced by the scaled T values. Since the ratio of scaled T's
            is identical to the ratio of reported T values, the scaling
            does not imply a change to the absorption corrections used in
            the study.
            Ratio of Tmax expected/reported      0.105
            Tmax scaled      0.105 Tmin scaled      0.060
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

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

   3 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
   4 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

1,3,5,7-Cyclooctatetraene (cot) is a widely utilized and versatile ligand in organometallic chemistry (Elschenbroich & Salzer, 1992). The cot ligand can coordinate metal atoms as a tub-shaped tetraene or as a planar aromatic anion C₈H₈^2-, and its coordination modes are quite variable, viz. η², η³, η⁴, η⁵, η⁶ and η⁸. Numerous cot-metal complexes are known, however, relatively few mono- and dinuclear Pt compounds with cot are synthesized and studied (Jensen, 1953; Doyle et al., 1961; Fritz & Keller, 1962; Kistner et al., 1963; Fritz & Sellmann, 1967; Tresoldi et al., 1982; Kunkely & Vogler, 2006). The decomposition of the mononuclear complexes, [(cot)PtR₂] (R = CH₃ or C₆H₅), lead to the formation of the dinuclear complexes, [R₂Pt(cot)PtR₂], in which cot acts as a bridging ligand between two Pt atoms. The NMR spectra of the dinuclear compounds were examined for potential long-range coupling by the ¹⁹⁵Pt nuclei (Kistner et al., 1963), and only the crystal structure of the dinuclear complex with CH₃ was reported (Doyle & Baenziger, 1995; Song et al., 2006). The X-ray structure analysis reveals that the complex contains a twofold axis passing through the Pt atoms and the center of the cot ligand. The dinuclear title complex, (I), was formed by the reaction of [(cot)Pt(CH₃)₂] with K₂PtCl₄ and its structure is reported here.

The complex consists of PtCl₂ and Pt(CH₃)₂ groups bridged by an 1,3,5,7-cyclooctatetraene ligand (Fig. 1), and is disposed about a mirror plane passing through the two Pt atoms and the center of the ligand (Fig. 2). Each Pt atom is essentially in a square-planar environment defined by the two midpoints of the π-coordinated double bonds of the cot ligand and the two Cl atoms or the two C atoms of methyl groups. The midpoints, the Pt and Cl or C atoms form two coordination planes with the largest deviations 0.002 Å (Pt1) from the least-squares planes. The bond angles lie in the range of 83.3°–95.5° (<Cl1—Pt1—Cl1ⁱ = 83.3 (2)°, <M1—Pt1—M1ⁱ = 85.7°, <Cl1—Pt1—M1 = 95.5°, <C5—Pt2—C6 = 85.1 (7)°, <M2—Pt2—M2ⁱ = 85.3°, <C6—Pt2—M1 = 94.2°, <C5—Pt2—M2 = 95.4°; symmetry code i: x, 1.5 - y, z; M1 and M2 denote the centroids of the olefinic bonds C1—C2 and C3—C3ⁱ, respectively). The coordination planes are perfectly perpendicular to each other (90.0°). The Pt—C(cot) bond lengths range from 2.249 (15) Å to 2.267 (16) Å, and are slightly longer than the Pt—C(methyl) bond (2.195 (17) Å and 2.137 (19) Å). The distances between the Pt atom and the midpoints are 2.156 Å (M1), 2.150 Å (M2) and 2.147 Å (M2ⁱ). The Pt1—C1/C2 bonds trans to Cl atom are, on an average, almost equal to the Pt2—C3/C4 bonds trans to methyl group (the mean lengths: Pt1—C1/C2 = 2.262 Å and Pt2—C3/C4 = 2.253 Å). The cot ligand coordinates the two Pt atoms very symmetrically in the tub conformation. The distance between the Pt atoms is 4.1407 (4) Å. The four C atoms (C1, C2, C1ⁱ and C2ⁱ) coordinated to Pt1 and the four C atoms (C3, C4, C3ⁱ and C4ⁱ) coordinated to Pt2 lie on a plane, respectively, with the torsion angles <C1—C2—C2ⁱ—C1ⁱ = 0° and <C3—C3ⁱ—C4ⁱ—C4 = 0°. The Pt atoms are displaced by 1.581 (12) Å (Pt1) from the plane C1/C2/C2ⁱ/C1ⁱ and 1.580 (10) Å (Pt2) from the plane C3/C3ⁱ/C4ⁱ/C4, respectively. The planes are nearly parallel to each other with dihedral angle 0.3(1.9)°. The cot ring angles lie in the range of 121.1 (15)°–122.6 (9)° in the complex.

Related literature

For related literature, see: Doyle & Baenziger (1995); Doyle et al. (1961); Elschenbroich & Salzer (1992); Fritz & Keller (1962); Fritz & Sellmann (1967); Jensen (1953); Kistner et al. (1963); Kunkely & Vogler (2006); Song et al. (2006); Tresoldi et al. (1982).

S2. Experimental

To a solution of cyclooctatetraenedimethylplatinum(II) (0.0724 g, 0.22 mmol) in CH₂Cl₂ (15 ml) and EtOH (15 ml) was added a solution of K₂PtCl₄ (0.1018 g, 0.25 mmol) in H₂O (10 ml), and stirred for 24 h at room temperature. The formed precipitate was collected by filtration, washed with CH₂Cl₂ and H₂O, and dried, giving a orange powder (0.0277 g). Needle-shaped crystals suitable for an X-ray structure analysis were obtained via slow evaporation from a CHCl₃ solution.

S3. Refinement

All H atoms were positioned geometrically and allowed to ride on their respective carrier atoms [C—H = 0.93 or 0.96 Å and U_iso(H) = 1.2U_eq(C) or 1.5U_eq(methyl C)].

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The structure of (I), showing the atom-numbering scheme (symmetry code a: x, 1.5 - y, z). Displacement ellipsoids are drawn at the 30% probability level and H atoms are represented by circles of arbitrary size.
	Fig. 2. A packing diagram for (I).

Dichlorido-1κ²Cl-µ-[(1,2,5,6-η:3,4,7,8-η)-1,3,5,7- cyclooctatetraene]dimethyl-2κ²C-diplatinum(II)

Crystal data

[Pt2(CH3)2Cl2(C8H8)]	F(000) = 1056
Mr = 595.29	Dx = 3.136 Mg m^−3
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 1985 reflections
a = 7.8478 (8) Å	θ = 2.4–25.0°
b = 10.3924 (10) Å	µ = 22.55 mm^−1
c = 15.4582 (16) Å	T = 293 K
V = 1260.7 (2) Å^3	Needle, orange
Z = 4	0.25 × 0.12 × 0.10 mm

Data collection

Bruker SMART 1000 CCD diffractometer	1363 independent reflections
Radiation source: fine-focus sealed tube	1226 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.050
φ and ω scans	θmax = 26.4°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −7→9
Tmin = 0.574, Tmax = 1.000	k = −12→12
7010 measured reflections	l = −19→17

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)] = 0.058	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.145	H-atom parameters constrained
S = 1.20	w = 1/[σ^2(Fo^2) + (0.0633P)^2 + 15.8923P] where P = (Fo^2 + 2Fc^2)/3
1363 reflections	(Δ/σ)max < 0.001
70 parameters	Δρmax = 1.77 e Å^−3
0 restraints	Δρmin = −1.95 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	0.82988 (12)	0.7500	−0.11111 (6)	0.0463 (3)
Pt2	0.43629 (11)	0.7500	0.06729 (6)	0.0388 (3)
Cl1	1.0022 (6)	0.5927 (5)	−0.1916 (3)	0.0579 (11)
C1	0.624 (2)	0.6080 (14)	−0.0752 (12)	0.045 (4)
H1	0.6470	0.5587	−0.1240	0.054*
C2	0.738 (2)	0.6098 (16)	−0.0088 (11)	0.051 (4)
H2	0.8374	0.5611	−0.0135	0.061*
C3	0.7102 (19)	0.6866 (15)	0.0704 (10)	0.044 (4)
H3	0.6917	0.6437	0.1224	0.053*
C4	0.4650 (18)	0.6831 (16)	−0.0708 (9)	0.041 (4)
H4	0.3615	0.6397	−0.0680	0.049*
C5	0.157 (2)	0.7500	0.0657 (12)	0.026 (4)
H5A	0.1171	0.7500	0.0069	0.039*
H5B	0.1152	0.8254	0.0947	0.039*
C6	0.410 (2)	0.7500	0.2049 (12)	0.036 (5)
H6A	0.5209	0.7500	0.2312	0.054*
H6B	0.3487	0.6746	0.2227	0.054*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pt1	0.0460 (6)	0.0553 (6)	0.0377 (6)	0.000	0.0031 (4)	0.000
Pt2	0.0409 (5)	0.0423 (5)	0.0331 (5)	0.000	0.0005 (4)	0.000
Cl1	0.060 (3)	0.070 (3)	0.043 (3)	0.016 (2)	0.0070 (19)	−0.001 (2)
C1	0.060 (10)	0.025 (7)	0.049 (11)	0.000 (7)	0.016 (8)	−0.004 (7)
C2	0.060 (10)	0.047 (9)	0.045 (10)	0.005 (8)	0.011 (8)	0.008 (8)
C3	0.048 (9)	0.045 (8)	0.038 (9)	0.014 (7)	0.006 (7)	0.013 (7)
C4	0.034 (7)	0.063 (9)	0.027 (8)	−0.007 (7)	0.003 (6)	−0.003 (7)
C5	0.022 (9)	0.035 (10)	0.020 (10)	0.000	−0.006 (7)	0.000
C6	0.029 (10)	0.063 (13)	0.015 (10)	0.000	−0.009 (8)	0.000

Geometric parameters (Å, º)

Pt1—C1	2.256 (16)	C1—C4	1.47 (2)
Pt1—C1^i	2.256 (16)	C1—H1	0.9300
Pt1—C2^i	2.267 (16)	C2—C3	1.48 (2)
Pt1—C2	2.267 (16)	C2—H2	0.9300
Pt1—Cl1	2.460 (4)	C3—C3^i	1.32 (3)
Pt1—Cl1^i	2.460 (4)	C3—H3	0.9300
Pt2—C6	2.137 (19)	C4—C4^i	1.39 (3)
Pt2—C5	2.195 (17)	C4—H4	0.9300
Pt2—C3^i	2.249 (15)	C5—H5A	0.9600
Pt2—C3	2.249 (15)	C5—H5B	0.9600
Pt2—C4	2.257 (15)	C6—H6A	0.9600
Pt2—C4^i	2.257 (15)	C6—H6B	0.9600
C1—C2	1.36 (3)
C1—Pt1—C1^i	81.7 (8)	C2—C1—C4	121.1 (15)
C1—Pt1—C2^i	91.3 (6)	C2—C1—Pt1	72.9 (10)
C1^i—Pt1—C2^i	35.1 (6)	C4—C1—Pt1	105.8 (10)
C1—Pt1—C2	35.1 (6)	C2—C1—H1	119.5
C1^i—Pt1—C2	91.3 (6)	C4—C1—H1	119.5
C2^i—Pt1—C2	80.0 (9)	Pt1—C1—H1	91.3
C1—Pt1—Cl1	94.8 (4)	C1—C2—C3	122.2 (16)
C1^i—Pt1—Cl1	162.3 (5)	C1—C2—Pt1	72.1 (10)
C2^i—Pt1—Cl1	162.6 (5)	C3—C2—Pt1	106.2 (10)
C2—Pt1—Cl1	95.7 (5)	C1—C2—H2	118.9
C1—Pt1—Cl1^i	162.3 (5)	C3—C2—H2	118.9
C1^i—Pt1—Cl1^i	94.8 (4)	Pt1—C2—H2	91.7
C2^i—Pt1—Cl1^i	95.7 (5)	C3^i—C3—C2	122.6 (9)
C2—Pt1—Cl1^i	162.6 (5)	C3^i—C3—Pt2	73.0 (4)
Cl1—Pt1—Cl1^i	83.3 (2)	C2—C3—Pt2	106.4 (11)
C6—Pt2—C5	85.1 (7)	C3^i—C3—H3	118.7
C6—Pt2—C3^i	94.0 (6)	C2—C3—H3	118.7
C5—Pt2—C3^i	163.0 (4)	Pt2—C3—H3	90.6
C6—Pt2—C3	94.0 (6)	C4^i—C4—C1	121.9 (9)
C5—Pt2—C3	163.0 (4)	C4^i—C4—Pt2	72.1 (4)
C3^i—Pt2—C3	34.1 (8)	C1—C4—Pt2	106.9 (10)
C6—Pt2—C4	162.0 (4)	C4^i—C4—H4	119.0
C5—Pt2—C4	95.1 (6)	C1—C4—H4	119.0
C3^i—Pt2—C4	90.9 (5)	Pt2—C4—H4	91.0
C3—Pt2—C4	80.5 (6)	Pt2—C5—H5A	109.5
C6—Pt2—C4^i	162.0 (4)	Pt2—C5—H5B	109.5
C5—Pt2—C4^i	95.1 (6)	H5A—C5—H5B	109.5
C3^i—Pt2—C4^i	80.5 (6)	Pt2—C6—H6A	109.5
C3—Pt2—C4^i	90.9 (5)	Pt2—C6—H6B	109.5
C4—Pt2—C4^i	35.9 (9)	H6A—C6—H6B	109.5
C1^i—Pt1—C1—C2	−104.3 (10)	C4—Pt2—C3—C3^i	106.0 (4)
C2^i—Pt1—C1—C2	−70.5 (12)	C4^i—Pt2—C3—C3^i	71.5 (4)
Cl1—Pt1—C1—C2	93.2 (10)	C6—Pt2—C3—C2	148.9 (10)
Cl1^i—Pt1—C1—C2	176.1 (11)	C5—Pt2—C3—C2	62 (3)
C1^i—Pt1—C1—C4	14.0 (14)	C3^i—Pt2—C3—C2	−119.9 (9)
C2^i—Pt1—C1—C4	47.8 (12)	C4—Pt2—C3—C2	−13.9 (10)
C2—Pt1—C1—C4	118.3 (16)	C4^i—Pt2—C3—C2	−48.4 (11)
Cl1—Pt1—C1—C4	−148.5 (10)	C2—C1—C4—C4^i	66.8 (17)
Cl1^i—Pt1—C1—C4	−65.6 (18)	Pt1—C1—C4—C4^i	−12.4 (12)
C4—C1—C2—C3	0 (2)	C2—C1—C4—Pt2	−12.3 (18)
Pt1—C1—C2—C3	98.2 (15)	Pt1—C1—C4—Pt2	−91.5 (9)
C4—C1—C2—Pt1	−98.4 (14)	C6—Pt2—C4—C4^i	−178 (2)
C1^i—Pt1—C2—C1	73.5 (11)	C5—Pt2—C4—C4^i	91.7 (2)
C2^i—Pt1—C2—C1	106.9 (9)	C3^i—Pt2—C4—C4^i	−72.4 (4)
Cl1—Pt1—C2—C1	−90.2 (9)	C3—Pt2—C4—C4^i	−105.0 (4)
Cl1^i—Pt1—C2—C1	−176.0 (11)	C6—Pt2—C4—C1	−60 (2)
C1—Pt1—C2—C3	−119.3 (16)	C5—Pt2—C4—C1	−149.5 (10)
C1^i—Pt1—C2—C3	−45.8 (12)	C3^i—Pt2—C4—C1	46.5 (11)
C2^i—Pt1—C2—C3	−12.4 (15)	C3—Pt2—C4—C1	13.9 (10)
Cl1—Pt1—C2—C3	150.5 (11)	C4^i—Pt2—C4—C1	118.9 (10)
Cl1^i—Pt1—C2—C3	65 (2)	C1—C2—C1^i—C2^i	180.000 (3)
C1—C2—C3—C3^i	−67.4 (18)	C3—C4^i—C3^i—C4	0.000 (5)
Pt1—C2—C3—C3^i	11.3 (13)	C4—C1—C2—C3	0 (2)
C1—C2—C3—Pt2	12.6 (19)	C4^i—C1^i—C2^i—C3^i	0 (2)
Pt1—C2—C3—Pt2	91.3 (10)	C1—C4—C3^i—C2^i	93.6 (12)
C6—Pt2—C3—C3^i	−91.2 (2)	C1^i—C4^i—C3—C2	−93.6 (12)
C5—Pt2—C3—C3^i	−178 (2)

Symmetry code: (i) x, −y+3/2, z.