Bromido[(1,2,5,6-η)-1,3,5,7-cyclo­octa­tetra­ene]methyl­platinum(II)

In the title complex, [PtBr(CH₃)(C₈H₈)], the Pt^II centre lies in a square-planar environment defined by the Br and methyl C atoms and the midpoints of the two π-coordinated double bonds of 1,3,5,7-cyclo­octa­tetra­ene. Because of the different trans influences of the Br atom and the methyl group, the Pt—C bonds trans to the methyl group are longer than those trans to the Br atom.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.032 Å
• R factor = 0.057
• wR factor = 0.176
• Data-to-parameter ratio = 19.9

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT061_ALERT_3_B Tmax/Tmin Range Test RR' too Large .............       0.75
PLAT232_ALERT_2_B Hirshfeld Test Diff (M-X)  Pt     -   Br      ..      18.70 su
PLAT342_ALERT_3_B Low Bond Precision on C-C Bonds (x 1000) Ang ...         33
PLAT369_ALERT_2_B Long   C(sp2)-C(sp2) Bond  C2     -   C3     ...       1.57 Ang.

Alert level C
PLAT366_ALERT_2_C Short? C(sp?)-C(sp?) Bond  C5     -   C6     ...       1.38 Ang.
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C1     -   C8     ...       1.56 Ang.

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K
PLAT794_ALERT_5_G Check Predicted Bond Valency for Pt          (2)       1.88

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

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

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S1. Comment

In the title complex, [Pt(CH₃)Br(C₈H₈)], the central Pt^II ion lies in an essentially square-planar environment defined by the Br and methyl C atoms and by the two mid-points (M1, M2) of the π-coordinated double bonds of the 1,3,5,7-cyclooctatetraene (cot) ligand (M1 and M2 denote the mid-points of the olefinic bonds C1—C2 and C5—C6, respectively). The Pt, Br, C9 atoms and the mid-points lie in a coordination plane with the largest deviation of 0.031 Å (M2) from the least-squares plane, and with bond angles in the range 88.0°–92.9°.

Owing to the different trans influences of the Br atom and methyl group, the Pt—C bonds trans to C9 are on average 0.173 Å longer than those trans to Br (mean lengths: Pt—C1/C2 = 2.314 Å, Pt—C5/C6 = 2.141 Å). The distances between the Pt atom and the mid-points are 2.227 Å (M1) and 2.027 Å (M2). The cot ligand coordinates symmetrically to the Pt atom in the "tub" conformation. The four coordinating C atoms (C1, C2, C5 and C6) and the four non-coordinating C atoms (C3, C4, C7 and C8) lie on respective planes, with the torsion angles C1—C2—C5—C6 = 0.2 (16)° and C3—C4—C7—C8 = -0.7 (18)°. The Pt atom is displaced by 1.524 (9) Å from the plane C1/C2/C5/C6, and by 2.503 (9) Å from the plane C3/C4/C7/C8. In the complex, the cot ring angles lie in the range 118 (2)° - 126 (2)°.

Related literature

For related literature, see: Song et al. (2007).

S2. Experimental

To a solution of cyclooctatetraenedimethylplatinum(II) (0.2035 g, 0.618 mmol) in CH₂Cl₂ (30 ml) was added hydrobromic acid (48%; 0.1120 g, 0.664 mmol), and stirred for 5 h at room temperature. The solvent was removed under vacuum, the residue was washed with pentane, dissolved in ether, and filtered through a plug of Al₂O₃ (1 cm x 2 cm). Evaporation of the solvent gave a yellow powder (0.0763 g). Large plates were obtained by slow evaporation from a CDCl₃ solution.

S3. Refinement

H atoms were positioned geometrically and allowed to ride on their respective carrier atoms, with C—H = 0.98, 0.93 or 0.96 Å and with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(methyl C).

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); 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: ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The structure of the title compound with displacement ellipsoids drawn at the 30% probability level for non-H atoms. Hydrogen atoms are shown as spheres of arbitrary radii.
	Fig. 2. View of the unit-cell contents of the title compound.

Bromido[(1,2,5,6-η)-1,3,5,7-cyclooctatetraene]methylplatinum(II)

Crystal data

[PtBr(CH3)(C8H8)]	F(000) = 712
Mr = 394.18	Dx = 2.674 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 1512 reflections
a = 8.3637 (12) Å	θ = 2.8–24.2°
b = 10.1098 (15) Å	µ = 18.35 mm^−1
c = 11.6897 (17) Å	T = 293 K
β = 97.928 (3)°	Plate, yellow
V = 979.0 (2) Å^3	0.12 × 0.10 × 0.08 mm
Z = 4

Data collection

Bruker SMART 1000 CCD diffractometer	2009 independent reflections
Radiation source: fine-focus sealed tube	1435 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.045
φ and ω scans	θmax = 26.4°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −10→8
Tmin = 0.095, Tmax = 0.230	k = −12→10
5568 measured reflections	l = −14→14

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)] = 0.057	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.176	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.1039P)^2] where P = (Fo^2 + 2Fc^2)/3
2009 reflections	(Δ/σ)max < 0.001
101 parameters	Δρmax = 3.68 e Å^−3
0 restraints	Δρmin = −2.52 e Å^−3

Special details

Experimental. The datum crystal was cut from a large plate of approximate dimensions 0.08 X 1.5 X 2.0 mm.

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
Pt	0.59256 (7)	0.30579 (7)	0.16610 (5)	0.0429 (3)
Br	0.36957 (17)	0.13420 (17)	0.12204 (16)	0.0469 (5)
C1	0.668 (2)	0.293 (2)	−0.0165 (17)	0.074 (7)
H1	0.5849	0.2611	−0.0775	0.088*
C2	0.749 (2)	0.2053 (18)	0.0419 (16)	0.050 (5)
H2	0.7231	0.1132	0.0207	0.060*
C3	0.923 (2)	0.234 (2)	0.106 (2)	0.068 (6)
H3	1.0085	0.1882	0.0819	0.081*
C4	0.956 (2)	0.320 (2)	0.1956 (18)	0.064 (6)
H4	1.0619	0.3357	0.2291	0.077*
C5	0.818 (2)	0.3893 (18)	0.2383 (17)	0.057 (5)
H5	0.8302	0.4016	0.3222	0.069*
C6	0.730 (2)	0.487 (2)	0.176 (2)	0.067 (6)
H6	0.6896	0.5572	0.2221	0.081*
C7	0.748 (3)	0.523 (3)	0.053 (2)	0.081 (7)
H7	0.7797	0.6088	0.0369	0.097*
C8	0.722 (3)	0.440 (3)	−0.028 (2)	0.084 (8)
H8	0.7352	0.4695	−0.1019	0.100*
C9	0.484 (2)	0.3641 (18)	0.3157 (12)	0.044 (4)
H9A	0.4693	0.2875	0.3617	0.066*
H9B	0.3808	0.4043	0.2910	0.066*
H9C	0.5527	0.4263	0.3607	0.066*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pt	0.0398 (4)	0.0485 (5)	0.0418 (4)	0.0024 (3)	0.0102 (3)	0.0010 (3)
Br	0.0252 (7)	0.0412 (10)	0.0735 (11)	−0.0053 (6)	0.0036 (7)	0.0021 (8)
C1	0.051 (12)	0.13 (2)	0.042 (11)	−0.032 (12)	0.010 (9)	−0.001 (12)
C2	0.043 (9)	0.060 (13)	0.050 (10)	0.022 (8)	0.019 (8)	0.010 (9)
C3	0.055 (11)	0.059 (14)	0.096 (17)	0.014 (10)	0.035 (11)	0.040 (12)
C4	0.049 (11)	0.082 (16)	0.062 (13)	−0.001 (10)	0.014 (9)	0.009 (11)
C5	0.053 (11)	0.048 (12)	0.068 (12)	−0.005 (9)	−0.002 (9)	0.000 (9)
C6	0.047 (11)	0.065 (14)	0.091 (16)	−0.020 (10)	0.011 (10)	−0.004 (11)
C7	0.082 (16)	0.063 (16)	0.101 (19)	−0.004 (12)	0.030 (15)	0.041 (14)
C8	0.070 (14)	0.14 (3)	0.047 (13)	0.002 (15)	0.015 (11)	0.040 (14)
C9	0.051 (9)	0.053 (11)	0.029 (8)	0.008 (8)	0.015 (7)	0.010 (7)

Geometric parameters (Å, º)

Pt—C5	2.129 (17)	C4—C5	1.50 (3)
Pt—C6	2.152 (19)	C4—H4	0.9300
Pt—C9	2.161 (15)	C5—C6	1.38 (3)
Pt—C1	2.31 (2)	C5—H5	0.9800
Pt—C2	2.318 (16)	C6—C7	1.52 (3)
Pt—Br	2.5472 (16)	C6—H6	0.9800
C1—C2	1.26 (3)	C7—C8	1.26 (3)
C1—C8	1.57 (3)	C7—H7	0.9300
C1—H1	0.9800	C8—H8	0.9300
C2—C3	1.57 (3)	C9—H9A	0.9600
C2—H2	0.9800	C9—H9B	0.9600
C3—C4	1.36 (3)	C9—H9C	0.9600
C3—H3	0.9300
C5—Pt—C6	37.5 (7)	C2—C3—H3	117.8
C5—Pt—C9	91.1 (7)	C3—C4—C5	118.0 (18)
C6—Pt—C9	90.3 (8)	C3—C4—H4	121.0
C5—Pt—C1	92.8 (8)	C5—C4—H4	121.0
C6—Pt—C1	83.4 (8)	C6—C5—C4	122.8 (19)
C9—Pt—C1	164.0 (8)	C6—C5—Pt	72.1 (11)
C5—Pt—C2	83.0 (7)	C4—C5—Pt	111.4 (14)
C6—Pt—C2	93.7 (8)	C6—C5—H5	114.4
C9—Pt—C2	164.4 (6)	C4—C5—H5	114.4
C1—Pt—C2	31.6 (7)	Pt—C5—H5	114.4
C5—Pt—Br	158.9 (5)	C5—C6—C7	124 (2)
C6—Pt—Br	163.5 (6)	C5—C6—Pt	70.4 (11)
C9—Pt—Br	88.3 (5)	C7—C6—Pt	106.3 (15)
C1—Pt—Br	93.5 (5)	C5—C6—H6	115.4
C2—Pt—Br	92.0 (5)	C7—C6—H6	115.4
C2—C1—C8	125.5 (19)	Pt—C6—H6	115.4
C2—C1—Pt	74.5 (12)	C8—C7—C6	121 (2)
C8—C1—Pt	98.5 (14)	C8—C7—H7	119.3
C2—C1—H1	115.7	C6—C7—H7	119.3
C8—C1—H1	115.7	C7—C8—C1	126 (2)
Pt—C1—H1	115.7	C7—C8—H8	117.1
C1—C2—C3	121.6 (18)	C1—C8—H8	117.1
C1—C2—Pt	73.9 (12)	Pt—C9—H9A	109.5
C3—C2—Pt	100.6 (13)	Pt—C9—H9B	109.5
C1—C2—H2	116.8	H9A—C9—H9B	109.5
C3—C2—H2	116.8	Pt—C9—H9C	109.5
Pt—C2—H2	116.8	H9A—C9—H9C	109.5
C4—C3—C2	124.4 (18)	H9B—C9—H9C	109.5
C4—C3—H3	117.8
C5—Pt—C1—C2	71.8 (13)	Br—Pt—C5—C6	−177.3 (12)
C6—Pt—C1—C2	108.1 (14)	C6—Pt—C5—C4	−119 (2)
C9—Pt—C1—C2	176 (2)	C9—Pt—C5—C4	152.0 (14)
Br—Pt—C1—C2	−88.1 (12)	C1—Pt—C5—C4	−43.6 (15)
C5—Pt—C1—C8	−52.8 (14)	C2—Pt—C5—C4	−13.5 (14)
C6—Pt—C1—C8	−16.4 (13)	Br—Pt—C5—C4	64 (2)
C9—Pt—C1—C8	51 (3)	C4—C5—C6—C7	8 (3)
C2—Pt—C1—C8	−124.6 (19)	Pt—C5—C6—C7	−97 (2)
Br—Pt—C1—C8	147.3 (12)	C4—C5—C6—Pt	104.4 (18)
C8—C1—C2—C3	−3 (3)	C9—Pt—C6—C5	91.5 (13)
Pt—C1—C2—C3	−92.8 (18)	C1—Pt—C6—C5	−103.3 (14)
C8—C1—C2—Pt	90 (2)	C2—Pt—C6—C5	−73.4 (13)
C5—Pt—C2—C1	−107.1 (14)	Br—Pt—C6—C5	176.6 (16)
C6—Pt—C2—C1	−71.1 (14)	C5—Pt—C6—C7	121 (2)
C9—Pt—C2—C1	−175 (2)	C9—Pt—C6—C7	−147.5 (14)
Br—Pt—C2—C1	93.5 (12)	C1—Pt—C6—C7	17.7 (14)
C5—Pt—C2—C3	13.0 (11)	C2—Pt—C6—C7	47.6 (15)
C6—Pt—C2—C3	49.0 (12)	Br—Pt—C6—C7	−62 (3)
C9—Pt—C2—C3	−55 (3)	C5—C6—C7—C8	61 (3)
C1—Pt—C2—C3	120.1 (18)	Pt—C6—C7—C8	−16 (3)
Br—Pt—C2—C3	−146.5 (10)	C6—C7—C8—C1	0 (4)
C1—C2—C3—C4	65 (3)	C2—C1—C8—C7	−63 (4)
Pt—C2—C3—C4	−12 (2)	Pt—C1—C8—C7	15 (3)
C2—C3—C4—C5	2 (3)	C1—C2—C5—C6	0.2 (16)
C3—C4—C5—C6	−71 (3)	C3—C4—C7—C8	−0.7 (18)
C3—C4—C5—Pt	11 (2)	C3—C2—C1—C8	−3 (3)
C9—Pt—C5—C6	−89.0 (13)	C4—C5—C6—C7	8 (3)
C1—Pt—C5—C6	75.4 (14)	C2—C3—C4—C5	2 (3)
C2—Pt—C5—C6	105.5 (13)	C6—C7—C8—C1	0 (4)