trans-1,4-Diphenyl-1,4-diphosphacyclo­hexa­ne

The mol­ecule of the title compound, C₁₆H₁₈P₂, which was prepared by the reaction of dichloro­ethane with lithia­ted bis­(diphenyl­phosphino)ethane, is disposed about a centre of symmetry. The 1,4-diphosphacyclo­hexane ring adopts a chair conformation with axial phenyl groups. The planes of the phenyl rings are orthogonal to the P...P axis.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C)= 0.004 Å
• R factor = 0.042
• wR factor = 0.132
• Data-to-parameter ratio = 19.6

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S1. Comment

The crystal structure of (I) has been previously reported as a preliminary communication without publication of the atom coordinates (Brooks et al., 1989). The molecules of (I) are disposed about a crystallographic centre of symmetry. The central 1,4-diphospha-cyclohexane ring adopts a chair conformation with the phenyl groups diaxial. The planes of the phenyl rings are approximately orthogonal to the P···P axis of the 1,4-diphospha-cyclohexane ring. The P—C bond lengths are similar with P—C(aliphatic) = 1.841 (3), 1.843 (2) Å and P—C(aromatic) 1.834 (2) Å. The endocyclic C—P—C angle is 100.3 (1)° compared to the exocyclic C—P—C angles of 102.70 (9) and 102.72 (10)°.

Related literature

For related literature, see: Brooks et al. (1989).

S2. Experimental

Bis(diphenylphosphino)ethane (dppe) (5.8 g, 0.015 mol) in dry THF (48 ml) was added dropwise over 4 hrs at 273 K to lithium (1.38 g, 0.20 mol) in dry THF (30 ml). The mixture was refluxed for 2 h. 5 ml of the lithiated dppe was then added to 1,2-dichloroethane (95 ml) at 273 K over 1 hr. The solution was stirred for 2 days, resulting in precipitation of solid material. The solvent was removed under vacuum to give a residual oil. Ethanol (50 ml) was added to this oil and the mixture placed in the freezer overnight to yield transparent well formed crystals of (I). yield 250 mg. m.p 438–443 K. Lit. (Brooks et al., 1989) 441–443 K).

S3. Refinement

Hydrogen atoms constrained in the riding model approximation, fixed to their parent C atoms with C—H set to 0.95 Å. U_iso values for the H atoms were set at 1.2U_eq of the parent atom.

Computing details

Data collection: MSC/AFC7 Diffractometer Control Software for Windows (Molecular Structure Corporation, 1999); cell refinement: MSC/AFC7 Diffractometer Control Software for Windows (Molecular Structure Corporation, 1999); data reduction: TEXSAN for Windows (Molecular Structure Corporation, 2001); program(s) used to solve structure: TEXSAN for Windows (Molecular Structure Corporation, 2001); program(s) used to refine structure: TEXSAN for Windows (Molecular Structure Corporation, 2001) and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: TEXSAN for Windows (Molecular Structure Corporation, 2001) and PLATON (Spek, 2003).

Figures

Fig. 1. View of the title compound with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 30% probability level. Symmetry code for symmetry related atoms ('): (-x, -y, 1 - z).

trans-1,4-Diphenyl-1,4-diphosphacyclohexane

Crystal data

C16H18P2	F(000) = 576
Mr = 272.24	Dx = 1.273 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 25 reflections
a = 16.585 (6) Å	θ = 12.5–16.6°
b = 11.584 (6) Å	µ = 0.29 mm^−1
c = 7.391 (3) Å	T = 295 K
V = 1420.0 (11) Å^3	Prism, colourless
Z = 4	0.40 × 0.30 × 0.30 mm

Data collection

Rigaku AFC-7R diffractometer	Rint = 0.029
Radiation source: Rigaku rotating anode	θmax = 27.5°, θmin = 3.0°
Graphite monochromator	h = 0→21
ω–2/q scans	k = −6→15
1879 measured reflections	l = −9→3
1627 independent reflections	3 standard reflections every 150 reflections
1139 reflections with I > 2σ(I)	intensity decay: 0.9%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.042	H-atom parameters constrained
wR(F^2) = 0.132	w = 1/[σ^2(Fo^2) + (0.0715P)^2 + 0.24P] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max < 0.001
1627 reflections	Δρmax = 0.47 e Å^−3
83 parameters	Δρmin = −0.34 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), FC^*=KFC[1+0.001XFC^2Λ^3/SIN(2Θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.007 (2)

Special details

Experimental. The scan width was (1.68 + 0.30tanθ)° with an ω scan speed of 16° per minute (up to 4 scans to achieve I/σ(I) > 10). Stationary background counts were recorded at each end of the scan, and the scan time:background time ratio was 2:1.

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All e.s.d.'s are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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
P1	0.01337 (3)	−0.07964 (5)	0.29128 (8)	0.0474 (2)
C1	0.12165 (13)	−0.10065 (18)	0.3298 (3)	0.0423 (6)
C2	0.17770 (15)	−0.0227 (2)	0.2600 (3)	0.0530 (7)
C3	0.25994 (15)	−0.0433 (3)	0.2746 (4)	0.0622 (8)
C4	0.28740 (13)	−0.1423 (3)	0.3555 (3)	0.0603 (8)
C5	0.23294 (15)	−0.2210 (2)	0.4236 (3)	0.0586 (8)
C6	0.15063 (13)	−0.20060 (19)	0.4110 (3)	0.0499 (7)
C7	0.00128 (12)	0.0773 (2)	0.3197 (3)	0.0481 (7)
C8	0.03159 (13)	0.13119 (18)	0.4954 (3)	0.0491 (7)
H2	0.15770	0.04710	0.20000	0.0620*
H3	0.29830	0.01270	0.22970	0.0730*
H4	0.34470	−0.15830	0.36490	0.0710*
H5	0.25200	−0.29160	0.47890	0.0660*
H6	0.11180	−0.25750	0.45820	0.0550*
H71	−0.05410	0.09350	0.30670	0.0540*
H72	0.03030	0.11240	0.22130	0.0540*
H81	0.08900	0.11660	0.50640	0.0460*
H82	0.02070	0.21320	0.49270	0.0550*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.0446 (3)	0.0532 (4)	0.0444 (4)	−0.0003 (2)	−0.0041 (2)	−0.0051 (3)
C1	0.0439 (10)	0.0463 (11)	0.0366 (10)	0.0020 (8)	0.0029 (8)	−0.0028 (8)
C2	0.0527 (13)	0.0528 (12)	0.0536 (13)	0.0047 (10)	0.0136 (10)	0.0066 (10)
C3	0.0489 (13)	0.0720 (16)	0.0658 (15)	−0.0036 (12)	0.0183 (12)	−0.0055 (13)
C4	0.0424 (11)	0.0850 (18)	0.0534 (13)	0.0088 (12)	0.0021 (10)	−0.0107 (13)
C5	0.0620 (14)	0.0655 (15)	0.0484 (12)	0.0194 (11)	−0.0010 (11)	0.0000 (11)
C6	0.0536 (12)	0.0507 (12)	0.0454 (11)	0.0038 (10)	0.0024 (9)	0.0023 (9)
C7	0.0455 (11)	0.0506 (12)	0.0482 (11)	0.0066 (9)	0.0042 (9)	0.0144 (9)
C8	0.0439 (11)	0.0389 (11)	0.0644 (14)	−0.0044 (9)	0.0070 (10)	0.0034 (10)

Geometric parameters (Å, º)

P1—C1	1.834 (2)	C2—H2	0.9800
P1—C7	1.841 (3)	C3—H3	0.9673
P1—C8^i	1.843 (2)	C4—H4	0.9707
C1—C2	1.395 (3)	C5—H5	0.9674
C1—C6	1.390 (3)	C6—H6	0.9853
C2—C3	1.389 (4)	C7—H71	0.9424
C3—C4	1.371 (5)	C7—H72	0.9622
C4—C5	1.379 (4)	C8—H81	0.9704
C5—C6	1.389 (3)	C8—H82	0.9672
C7—C8	1.526 (3)
P1···P1^i	3.622 (2)	C8···H6^i	2.8132
P1···H4^ii	3.1604	H2···C7	2.7632
C2···C8	3.475 (4)	H2···H72	2.2498
C2···C4^iii	3.595 (4)	H2···C4^iii	2.9203
C4···C2^iv	3.595 (4)	H4···P1^vi	3.1604
C6···C7^i	3.514 (4)	H5···C3^vii	2.9072
C7···C6^i	3.514 (4)	H5···C4^vii	2.9459
C8···C2	3.475 (4)	H6···C8^i	2.8132
C1···H71^i	2.9120	H6···H82^i	2.2856
C1···H81	2.8862	H71···C1^i	2.9120
C2···H81	2.8433	H71···C6^i	2.9079
C2···H72	2.9167	H72···C2	2.9167
C3···H5^v	2.9072	H72···H2	2.2498
C4···H5^v	2.9459	H81···C1	2.8862
C4···H2^iv	2.9203	H81···C2	2.8433
C6···H71^i	2.9079	H82···C6^i	2.9329
C6···H82^i	2.9329	H82···H6^i	2.2856
C7···H2	2.7632
C1—P1—C7	102.70 (9)	C3—C4—H4	121.07
C1—P1—C8^i	102.72 (10)	C5—C4—H4	119.28
C7—P1—C8^i	100.27 (10)	C4—C5—H5	119.95
P1—C1—C2	120.60 (17)	C6—C5—H5	119.57
P1—C1—C6	121.07 (16)	C1—C6—H6	118.95
C2—C1—C6	117.9 (2)	C5—C6—H6	120.33
C1—C2—C3	121.0 (2)	P1—C7—H71	106.93
C2—C3—C4	120.2 (3)	P1—C7—H72	106.05
C3—C4—C5	119.7 (2)	C8—C7—H71	109.05
C4—C5—C6	120.5 (2)	C8—C7—H72	107.79
C1—C6—C5	120.7 (2)	H71—C7—H72	109.04
P1—C7—C8	117.72 (15)	C7—C8—H81	108.86
P1^i—C8—C7	117.52 (15)	C7—C8—H82	108.83
C1—C2—H2	118.42	H81—C8—H82	110.85
C3—C2—H2	120.62	P1^i—C8—H81	105.59
C2—C3—H3	120.27	P1^i—C8—H82	105.09
C4—C3—H3	119.48
C7—P1—C1—C2	−40.7 (2)	P1—C1—C6—C5	173.61 (17)
C7—P1—C1—C6	146.59 (19)	C2—C1—C6—C5	0.7 (3)
C8^i—P1—C1—C2	−144.49 (18)	C6—C1—C2—C3	−1.3 (3)
C8^i—P1—C1—C6	42.8 (2)	C1—C2—C3—C4	1.2 (4)
C1—P1—C7—C8	−54.41 (18)	C2—C3—C4—C5	−0.5 (4)
C8^i—P1—C7—C8	51.27 (17)	C3—C4—C5—C6	−0.1 (4)
C1—P1—C8^i—C7^i	54.53 (18)	C4—C5—C6—C1	0.0 (3)
C7—P1—C8^i—C7^i	−51.14 (18)	P1—C7—C8—P1^i	−59.9 (2)
P1—C1—C2—C3	−174.2 (2)

Symmetry codes: (i) −x, −y, −z+1; (ii) x−1/2, y, −z+1/2; (iii) −x+1/2, −y, z−1/2; (iv) −x+1/2, −y, z+1/2; (v) x, −y−1/2, z−1/2; (vi) x+1/2, y, −z+1/2; (vii) x, −y−1/2, z+1/2.