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The crystal structure of the title compound, (bi­cyclo­[2.2.1]­hepta-2,5-diene)­di­chloro­platinum(II), [PtCl2(C7H8)], has been determined from single-crystal X-ray analysis. The coordination sphere about the Pt atom is pseudo-square planar, with shorter Pt-C distances than in the corresponding di­chloro­(cyclo­octa­diene)­platinum(II) complex.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104012491/na1667sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270104012491/na1667Isup2.hkl
Contains datablock I

CCDC reference: 245869

Comment top

In platinum(II) chemistry, norbornadiene (NBD) is generally considered to be a more labile ligand than 1,5-cyclooctadiene (COD) (Appleton et al., 1986, 1989). This lability is often attributed to the smaller bite angle of the chelating NBD ligand versus COD. However, there are very few corresponding structurally characterized COD (Klein et al., 1999) and NBD (Kickelbick et al., 2002) platinum(II) complexes. We now report the crystal structure of the title compound, (NBD)PtCl2, (I), and compare it with that of (COD)PtCl2, (II) (Syed et al., 1984). \sch

The two Cl atoms and the centroids of the alkene NBD bonds form an essentially square-planar environment around the Pt atom in (I). The bite angle, as defined by the angle between the two alkene centroid positions and the Pt, is 70.3°. This is similar to what has been observed in other (NBD)PtII complexes, such as (NBD)Pt(Cl)Me (69.1°; Kickelbick et al., 2002) and (NBD)Pt(2-ethoxynapth-1-yl)2 (70.4°; Debaerdemaeker et al., 1987), but is significantly smaller than the bite angle of 87.3° found for (II), as expected. The Cl—Pt—Cl bond angle in (I) [92.02 (8)°] is slightly larger than the corresponding angle in (II) [89.78 (5)°] and this is most likely due to the different bite angles of the NBD and COD supporting ligands.

The Pt—C bond lengths in (I) do not reflect the enhanced lability of the NBD chelate. They are, in fact, significantly shorter than those found in (II): the average Pt—C bond length in (I) is 2.145 Å, versus 2.170 Å in (II). Therefore, the increased lability often observed for NBD in PtII systems cannot be attributed to a loosely bound NBD ligand, but probably results from relief of binding strain associated with the small bite angle. The Pt—Cl bond lengths in (I), as well as the C—C alkene bond lengths, are very similar to those found in (II), indicating that NBD and COD have similar donating abilities.

Experimental top

We have recently reported an improved synthesis of (I) (Butikofer et al., 2004). Single crystals of (I) were obtained by heating a benzene solution of (NBD)Pt(CH2Cl)2 at 373 K in a sealed NMR tube. Formation of (I) most likely resulted from thermal decomposition (via ethylene loss) of the chloromethyl species at these temperatures.

Refinement top

H atoms were added in calculated positions and treated as riding, with C—H distances in the range 0.97–0.98 Å and with Uiso(H) = 1.2Ueq(C). Please check added text.

Computing details top

Data collection: XSCANS (Bruker, 1997); cell refinement: XSCANS; data reduction: SHELXTL (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing 30% probability displacement ellipsoids. H atoms have been omitted for clarity.
(bicyclo[2.2.1]hepta-2,5-diene)dichloroplatinum(II) top
Crystal data top
[PtCl2(C7H8)]F(000) = 1296
Mr = 358.12Dx = 2.946 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
a = 12.8717 (17) ÅCell parameters from 35 reflections
b = 11.5173 (12) Åθ = 4.8–12.5°
c = 12.6441 (13) ŵ = 17.95 mm1
β = 120.507 (12)°T = 298 K
V = 1615.0 (3) Å3Rectangular prism, colorless
Z = 80.52 × 0.12 × 0.08 mm
Data collection top
Bruker P4
diffractometer
1559 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.055
Graphite monochromatorθmax = 27.5°, θmin = 2.6°
ω scansh = 116
Absorption correction: ψ scan
(SHELXL97; Sheldrick, 1997)
k = 114
Tmin = 0.080, Tmax = 0.237l = 1614
2291 measured reflections3 standard reflections every 97 reflections
1843 independent reflections intensity decay: 1%
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.035Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.090H-atom parameters constrained
S = 1.06 w = 1 /[σ2(Fo2) + (0.0552P)2]
where P = (Fo2 + 2Fc2)/3
1843 reflections(Δ/σ)max < 0.001
91 parametersΔρmax = 2.00 e Å3
0 restraintsΔρmin = 2.24 e Å3
Crystal data top
[PtCl2(C7H8)]V = 1615.0 (3) Å3
Mr = 358.12Z = 8
Monoclinic, C2/cMo Kα radiation
a = 12.8717 (17) ŵ = 17.95 mm1
b = 11.5173 (12) ÅT = 298 K
c = 12.6441 (13) Å0.52 × 0.12 × 0.08 mm
β = 120.507 (12)°
Data collection top
Bruker P4
diffractometer
1559 reflections with I > 2σ(I)
Absorption correction: ψ scan
(SHELXL97; Sheldrick, 1997)
Rint = 0.055
Tmin = 0.080, Tmax = 0.2373 standard reflections every 97 reflections
2291 measured reflections intensity decay: 1%
1843 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0350 restraints
wR(F2) = 0.090H-atom parameters constrained
S = 1.06Δρmax = 2.00 e Å3
1843 reflectionsΔρmin = 2.24 e Å3
91 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
Pt10.13972 (2)0.35839 (2)0.04013 (2)0.02254 (12)
Cl10.17622 (18)0.4248 (2)0.11005 (18)0.0372 (4)
Cl20.30434 (18)0.45664 (18)0.19149 (19)0.0382 (5)
C10.1149 (7)0.2400 (7)0.1566 (7)0.0314 (18)
H1A0.17970.21860.23900.038*
C20.0411 (8)0.3364 (7)0.1333 (8)0.0338 (19)
H2A0.04960.38900.19810.041*
C30.0808 (8)0.3064 (8)0.0211 (9)0.0371 (19)
H3A0.15040.35340.00640.045*
C40.0452 (7)0.3083 (8)0.0774 (8)0.0320 (17)
H4A0.09670.34110.15940.038*
C50.0280 (7)0.2123 (8)0.0555 (7)0.0311 (17)
H5A0.03270.17130.12080.037*
C60.0397 (8)0.1509 (7)0.0570 (9)0.0353 (19)
H6A0.06760.07010.07130.042*
C70.0878 (8)0.1761 (8)0.0369 (10)0.040 (2)
H7C0.15170.13900.03610.048*
H7A0.09460.15670.10780.048*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Pt10.01997 (17)0.02581 (18)0.01700 (18)0.00235 (11)0.00585 (13)0.00180 (11)
Cl10.0378 (10)0.0506 (12)0.0246 (9)0.0057 (10)0.0170 (8)0.0008 (9)
Cl20.0333 (10)0.0415 (11)0.0264 (9)0.0129 (8)0.0054 (8)0.0085 (9)
C10.032 (4)0.040 (4)0.011 (3)0.004 (3)0.002 (3)0.008 (3)
C20.043 (5)0.034 (4)0.034 (5)0.013 (4)0.027 (4)0.013 (4)
C30.027 (4)0.037 (5)0.048 (5)0.002 (4)0.020 (4)0.006 (4)
C40.016 (3)0.046 (5)0.022 (4)0.009 (3)0.000 (3)0.003 (4)
C50.024 (4)0.041 (5)0.018 (4)0.007 (3)0.003 (3)0.008 (3)
C60.038 (5)0.020 (4)0.047 (6)0.007 (3)0.021 (4)0.000 (3)
C70.039 (5)0.038 (5)0.045 (6)0.007 (4)0.023 (5)0.002 (4)
Geometric parameters (Å, º) top
Pt1—C22.140 (8)C3—C71.522 (12)
Pt1—C52.144 (8)C3—C41.530 (12)
Pt1—C12.146 (7)C3—H3A0.9800
Pt1—C42.148 (7)C4—C51.386 (12)
Pt1—Cl22.3056 (19)C4—H4A0.9800
Pt1—Cl12.3058 (19)C5—C61.525 (12)
C1—C21.391 (12)C5—H5A0.9800
C1—C61.529 (11)C6—C71.555 (12)
C1—H1A0.9800C6—H6A0.9800
C2—C31.528 (13)C7—H7C0.9700
C2—H2A0.9800C7—H7A0.9700
C2—Pt1—C578.5 (3)C2—C3—C499.3 (6)
C2—Pt1—C137.9 (3)C7—C3—H3A117.4
C5—Pt1—C166.2 (3)C2—C3—H3A117.4
C2—Pt1—C465.8 (3)C4—C3—H3A117.4
C5—Pt1—C437.7 (3)C5—C4—C3106.3 (7)
C1—Pt1—C478.8 (3)C5—C4—Pt171.0 (4)
C2—Pt1—Cl298.8 (2)C3—C4—Pt197.2 (5)
C5—Pt1—Cl2157.5 (2)C5—C4—H4A123.0
C1—Pt1—Cl297.8 (2)C3—C4—H4A123.0
C4—Pt1—Cl2159.2 (2)Pt1—C4—H4A123.0
C2—Pt1—Cl1156.7 (3)C4—C5—C6107.0 (7)
C5—Pt1—Cl198.9 (2)C4—C5—Pt171.3 (5)
C1—Pt1—Cl1159.9 (2)C6—C5—Pt196.8 (5)
C4—Pt1—Cl197.9 (2)C4—C5—H5A122.9
Cl2—Pt1—Cl192.02 (8)C6—C5—H5A122.9
C2—C1—C6106.4 (7)Pt1—C5—H5A122.9
C2—C1—Pt170.8 (5)C5—C6—C1100.2 (6)
C6—C1—Pt196.5 (5)C5—C6—C799.4 (7)
C2—C1—H1A123.2C1—C6—C7100.6 (7)
C6—C1—H1A123.2C5—C6—H6A117.7
Pt1—C1—H1A123.2C1—C6—H6A117.7
C1—C2—C3106.6 (7)C7—C6—H6A117.7
C1—C2—Pt171.3 (5)C3—C7—C694.5 (6)
C3—C2—Pt197.6 (5)C3—C7—H7C112.8
C1—C2—H2A122.8C6—C7—H7C112.8
C3—C2—H2A122.8C3—C7—H7A112.8
Pt1—C2—H2A122.8C6—C7—H7A112.8
C7—C3—C2101.7 (7)H7C—C7—H7A110.3
C7—C3—C4100.5 (8)

Experimental details

Crystal data
Chemical formula[PtCl2(C7H8)]
Mr358.12
Crystal system, space groupMonoclinic, C2/c
Temperature (K)298
a, b, c (Å)12.8717 (17), 11.5173 (12), 12.6441 (13)
β (°) 120.507 (12)
V3)1615.0 (3)
Z8
Radiation typeMo Kα
µ (mm1)17.95
Crystal size (mm)0.52 × 0.12 × 0.08
Data collection
DiffractometerBruker P4
diffractometer
Absorption correctionψ scan
(SHELXL97; Sheldrick, 1997)
Tmin, Tmax0.080, 0.237
No. of measured, independent and
observed [I > 2σ(I)] reflections
2291, 1843, 1559
Rint0.055
(sin θ/λ)max1)0.650
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.035, 0.090, 1.06
No. of reflections1843
No. of parameters91
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)2.00, 2.24

Computer programs: XSCANS (Bruker, 1997), XSCANS, SHELXTL (Bruker, 1997), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), SHELXTL.

Selected geometric parameters (Å, º) top
Pt1—C22.140 (8)Pt1—Cl22.3056 (19)
Pt1—C52.144 (8)Pt1—Cl12.3058 (19)
Pt1—C12.146 (7)C1—C21.391 (12)
Pt1—C42.148 (7)C4—C51.386 (12)
C5—Pt1—C166.2 (3)C5—Pt1—Cl198.9 (2)
C2—Pt1—C465.8 (3)C4—Pt1—Cl197.9 (2)
C2—Pt1—Cl298.8 (2)Cl2—Pt1—Cl192.02 (8)
C1—Pt1—Cl297.8 (2)
 

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