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Acta Cryst. (2008). E64, o421    [ doi:10.1107/S1600536807068547 ]

1,2-Bis{bis[4-(trifluoromethyl)phenyl]phosphino}ethane

M. A. Bork, A. M. Krueger, R. S. Tanke and J. G. Brummer

Abstract top

Crystals of the title compound, C30H20F12P2 or R2PCH2CH2PR2 (R = 4-C6H4CF3), were inadvertently prepared while attempting to recrystallize a crude sample of trans-Re(Cl)(N2)(R2PCH2CH2PR2)2 from diethyl ether. The molecule lies on a center of inversion. One of the rings lies approximately in the P-C-C-P plane; the dihedral angle is 174.53°.The other ring is not quite perpendicular; the dihedral angle is 71.1°. The compound is isostructural with the R = Ph, 4-C6H4CH3 and 4-C6H4CH2CH3 analogues. It is well known that the basicity of phosphines and diphosphines can be altered by changing the electron-donating ability of R; however, the structural parameters for the title compound do not significantly differ from those of the aforementioned substituted-phenyl compounds.

Comment top

1,2-Bis{bis[4-(trifluoromethyl)phenyl]phosphino}ethane was obtained accidently during the recrystallization of trans-Re(Cl)(N2)(R2PCH2CH2PR2)2[R = 4-Ph—CF3] from diethyl ether. We were interested in preparing this complex in order to measure its luminescent properties and then compare them to those for the analogous R = Ph, 4-Ph-OCH3, and CH2CH3 complexes. Our preliminary results indicate that these complexes show simultaneous emission from two excited levels of different orbital parentage. Our intent is to investigate how changes in diphosphine basicity brought about by variations in R influence the bandshape and lifetimes of these emissions thereby allowing us to assign the excited states responsible for luminescence.

The title compound resides on a center of inversion. It is isostructural to its R = Ph, 4-Ph—CH3, and 4-Ph—CH2CH3 analogues. It is well known that the basicity of phosphines and diphosphines can be altered by changing the electron donating ability of R; however, the structural parameters for the title compound do not significantly differ from the aforementioned phenyl substituted compounds.

A summary of the C—P bond distances, C—P—C bond angles, and sums of the C—P—C angles is given in Table 1 for this work and several related diphosphines that contain aromatic and aliphatic substituents. The title compound has nearly identical geoemtric parameters about phosphorus as the other phenyl diphosphines and there appears to be no experimentally significant trends that parallel the electron donating ability of the para-substituent, which follows the order CH3CH2> CH3> H > CF3 (Nordwig et al., 2006; Allman & Goel, 1982; Tolman, 1970; Streuli, 1960). The aromatic diphosphines display Σ C—P—C values of about 303.5° which indicates a pyramidal arrangement of the bonds about phosphorus. The aliphatic diphosphines are more electron donating with the less sterically demanding R = CH3 and CH2CH3 cases giving rise to lower ΣC—P—C values. The R = CH(CH3)2 and C(CH3)3 compounds display larger ΣC—P—C values and longer C—P bond distances due to increased space requirements for these bulkier substituents. Substituent effects for the alkyl substituted compounds have been discussed previously (Bruckmann & Kruger, 1997; Eisentrager et al., 2003).

One of the rings lines approximately in the P—C—C—P plane; the dihedral angle is 174.53°.The other ring is not quite perpendicular; the dihedral angle is 71.1°.

Related literature top

For the synthesis of the title compound, see Chatt et al. (1985) For the crystal structures of similar 1,2-bis(diphenylphosphino)ethane structures, see Tiekink (2001); Zeller et al. (2003); Zeller & Hunter (2004). For related literature, see: Allman & Goel (1982); Larson (1970); Nordwig et al. (2006); Streuli (1960); Tolman (1970).

Experimental top

A non-crystalline sample of R2PCH2CH2PR2 [R = 4-Ph—CF3] and a crude sample of trans-Re(Cl)(N2)(R2PCH2CH2PR2)2 [R = 4-Ph—CF3] were prepared according to previously reported methods (Chatt, et al., 1985). Crude trans-Re(Cl)(N2)(R2PCH2CH2PR2)2 was dissolved in a minimum of diethyl ether at 20° C. The yellow-orange solution was filtered and ether was gradually evaporated by passing a slow stream of nitrogen gas through the flask. A mixture of microcrystalline orange solid and pale yellow-orange crystals formed over the course of 4 h. A pale crystal from this mixture was analyzed.

Refinement top

Reflections (11) in the vicinity of the beam stop, with [sin θ/λ] 2 < 0.01, were eliminated from the refinement.

All H atoms were positioned geometrically and refined using a riding model, with C—H = 0.93 Å for aromatic H atoms and 0.96 Å for methylene H atoms, and with Uiso(H) = 1.2 Ueq (C). An extinction correction (Larson, 1970) was applied.

Computing details top

Data collection: APEX2 (Bruker, 2006); cell refinement: APEX2 (Bruker, 2006); data reduction: APEX2 (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003).

Figures top
[Figure 1] Fig. 1. The title compound with displacement ellipsoids drawn at the 50% probability level. Symmetry code: i = -x + 2, -y + 2, -z.
1,2-Bis{bis[4-(trifluoromethyl)phenyl]phosphino}ethane top
Crystal data top
C30H20F12P2F000 = 676
Mr = 670.41Dx = 1.516 Mg m−3
Monoclinic, P21/nMelting point: 471 K
Hall symbol: -P 2ynMo Kα radiation
λ = 0.71073 Å
a = 15.188 (11) ÅCell parameters from 4592 reflections
b = 5.402 (4) Åθ = 2.3–27.2º
c = 18.123 (13) ŵ = 0.25 mm−1
β = 99.044 (9)ºT = 208 K
V = 1468.3 (19) Å3Block, colorless
Z = 20.40 × 0.10 × 0.10 mm
Data collection top
Bruker SMART APEXII
diffractometer		3240 independent reflections
Radiation source: fine-focus sealed tube2616 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.044
T = 208 Kθmax = 27.2º
ω scansθmin = 1.6º
Absorption correction: multi-scan
(SADABS; Sheldrick, 2006)		h = −19→19
Tmin = 0.91, Tmax = 0.98k = −4→6
9947 measured reflectionsl = −23→17
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.061  Method = Modified Sheldrick w = 1/[σ2(F2) + ( 0.07P)2 + 1.82P] ,
where P = (max(Fo2,0) + 2Fc2)/3
wR(F2) = 0.162(Δ/σ)max = 0.001
S = 0.95Δρmax = 0.73 e Å−3
3229 reflectionsΔρmin = −0.43 e Å−3
208 parametersExtinction correction: Larson (1970), Equation 22
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 100 (30)
Crystal data top
C30H20F12P2V = 1468.3 (19) Å3
Mr = 670.41Z = 2
Monoclinic, P21/nMo Kα
a = 15.188 (11) ŵ = 0.25 mm−1
b = 5.402 (4) ÅT = 208 K
c = 18.123 (13) Å0.40 × 0.10 × 0.10 mm
β = 99.044 (9)º
Data collection top
Bruker SMART APEXII
diffractometer		3240 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2006)		2616 reflections with I > 2σ(I)
Tmin = 0.91, Tmax = 0.98Rint = 0.044
9947 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.061208 parameters
wR(F2) = 0.162H-atom parameters constrained
S = 0.95Δρmax = 0.73 e Å−3
3229 reflectionsΔρmin = −0.43 e Å−3
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
F11.27583 (17)0.8551 (5)0.42720 (14)0.0973
F21.22595 (19)0.5004 (4)0.40090 (12)0.0933
F31.15394 (18)0.7552 (7)0.45867 (12)0.1188
F40.58890 (16)0.7965 (6)0.11270 (19)0.1126
F50.56328 (18)1.1552 (8)0.0760 (3)0.1601
F60.59438 (18)1.0822 (8)0.19080 (19)0.1525
C11.02538 (17)0.9577 (5)0.03782 (13)0.0376
C21.06731 (16)1.0281 (5)0.19636 (13)0.0366
C31.12029 (18)0.8196 (5)0.19746 (14)0.0432
C41.16363 (19)0.7219 (6)0.26452 (15)0.0474
C51.15250 (17)0.8323 (5)0.33151 (14)0.0422
C61.1999 (2)0.7337 (7)0.40384 (16)0.0566
C71.0996 (2)1.0400 (6)0.33167 (15)0.0501
C81.05801 (19)1.1393 (6)0.26470 (15)0.0466
C90.89383 (17)1.1273 (5)0.11969 (14)0.0375
C100.8645 (2)0.9282 (6)0.15831 (18)0.0531
C110.7744 (2)0.8957 (7)0.16050 (19)0.0600
C120.71295 (19)1.0603 (6)0.12370 (17)0.0530
C130.6158 (2)1.0234 (9)0.1269 (3)0.0781
C140.7406 (2)1.2566 (7)0.08562 (19)0.0587
C150.83094 (19)1.2916 (6)0.08420 (17)0.0488
P11.01119 (4)1.18369 (12)0.11177 (3)0.0363
H111.08760.94290.03440.0451*
H121.00280.79980.05030.0451*
H311.12700.74330.15270.0513*
H411.20060.58450.26470.0539*
H711.09181.11220.37680.0578*
H811.02321.28100.26480.0543*
H1010.90590.81540.18190.0610*
H1110.75480.76430.18680.0685*
H1410.69891.36740.06140.0680*
H1510.84991.42600.05870.0563*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
F10.0832 (16)0.114 (2)0.0773 (15)−0.0152 (14)−0.0410 (12)0.0092 (14)
F20.135 (2)0.0749 (15)0.0578 (13)0.0188 (14)−0.0231 (13)0.0109 (11)
F30.0998 (19)0.211 (3)0.0491 (12)0.057 (2)0.0224 (12)0.0483 (17)
F40.0612 (14)0.128 (2)0.155 (3)−0.0417 (15)0.0383 (15)−0.065 (2)
F50.0438 (14)0.213 (4)0.219 (4)0.0033 (19)0.0043 (19)0.058 (3)
F60.0792 (17)0.252 (4)0.143 (3)−0.069 (2)0.0692 (18)−0.128 (3)
C10.0375 (12)0.0447 (14)0.0301 (12)−0.0025 (11)0.0036 (9)−0.0012 (10)
C20.0352 (12)0.0416 (13)0.0321 (11)−0.0035 (10)0.0022 (9)−0.0015 (10)
C30.0476 (14)0.0499 (15)0.0306 (12)0.0024 (12)0.0015 (10)−0.0059 (11)
C40.0480 (15)0.0504 (16)0.0419 (14)0.0086 (12)0.0012 (11)−0.0001 (12)
C50.0368 (13)0.0543 (16)0.0338 (12)−0.0062 (11)0.0003 (10)0.0016 (11)
C60.0545 (17)0.076 (2)0.0371 (14)0.0052 (16)−0.0006 (13)0.0024 (14)
C70.0527 (16)0.0644 (19)0.0323 (13)0.0042 (14)0.0036 (11)−0.0087 (12)
C80.0488 (15)0.0506 (16)0.0396 (14)0.0089 (12)0.0043 (11)−0.0060 (12)
C90.0380 (12)0.0408 (13)0.0330 (12)−0.0019 (10)0.0041 (10)−0.0020 (10)
C100.0447 (15)0.0549 (18)0.0584 (17)−0.0033 (13)0.0041 (13)0.0165 (14)
C110.0525 (17)0.066 (2)0.0627 (19)−0.0154 (15)0.0142 (15)0.0084 (16)
C120.0403 (14)0.068 (2)0.0514 (16)−0.0054 (14)0.0108 (12)−0.0176 (15)
C130.0438 (18)0.106 (3)0.087 (3)−0.011 (2)0.0157 (18)−0.029 (2)
C140.0437 (16)0.067 (2)0.0638 (19)0.0105 (15)0.0027 (14)0.0007 (16)
C150.0469 (15)0.0491 (16)0.0507 (16)0.0045 (13)0.0090 (12)0.0101 (13)
P10.0368 (4)0.0389 (4)0.0320 (3)−0.0041 (3)0.0022 (2)0.0012 (2)
Geometric parameters (Å, °) top
F1—C61.336 (4)C2—C31.383 (4)
F2—C61.324 (4)C2—C81.403 (4)
F3—C61.307 (4)C2—P11.836 (3)
F4—C131.305 (5)C3—C41.392 (4)
F5—C131.328 (6)C3—H310.930
F6—C131.290 (5)C4—C51.387 (4)
H101—C100.930C5—C61.492 (4)
H111—C110.930C5—C71.380 (4)
H141—C140.930C7—C81.385 (4)
H151—C150.930C9—C101.394 (4)
H41—C40.930C9—C151.386 (4)
H71—C70.930C9—P11.836 (3)
H81—C80.930C10—C111.386 (4)
C1—C1i1.533 (5)C11—C121.383 (5)
C1—P11.850 (3)C12—C131.499 (5)
C1—H110.960C12—C141.367 (5)
C1—H120.960C14—C151.389 (4)
C1i—C1—P1110.6 (2)C7—C8—H81119.9
C1i—C1—H11109.3C10—C9—C15118.4 (3)
P1—C1—H11109.2C10—C9—P1123.9 (2)
C1i—C1—H12109.1C15—C9—P1117.7 (2)
P1—C1—H12109.2C9—C10—H101119.3
H11—C1—H12109.5C9—C10—C11120.5 (3)
C3—C2—C8118.3 (2)H101—C10—C11120.2
C3—C2—P1125.28 (19)C10—C11—H111120.6
C8—C2—P1116.3 (2)C10—C11—C12120.0 (3)
C2—C3—C4121.0 (2)H111—C11—C12119.4
C2—C3—H31119.5C11—C12—C13119.3 (3)
C4—C3—H31119.5C11—C12—C14120.3 (3)
C3—C4—H41120.6C13—C12—C14120.4 (3)
C3—C4—C5119.7 (3)C12—C13—F5112.9 (4)
H41—C4—C5119.7C12—C13—F4113.4 (3)
C4—C5—C6120.5 (3)F5—C13—F4103.3 (4)
C4—C5—C7120.2 (2)C12—C13—F6113.0 (3)
C6—C5—C7119.3 (3)F5—C13—F6106.4 (4)
C5—C6—F1112.1 (3)F4—C13—F6107.0 (4)
C5—C6—F2114.2 (3)H141—C14—C12119.8
F1—C6—F2103.4 (3)H141—C14—C15120.4
C5—C6—F3113.2 (3)C12—C14—C15119.8 (3)
F1—C6—F3104.7 (3)C14—C15—C9121.0 (3)
F2—C6—F3108.3 (3)C14—C15—H151119.9
C5—C7—H71119.8C9—C15—H151119.1
C5—C7—C8119.9 (3)C1—P1—C2102.20 (13)
H71—C7—C8120.3C1—P1—C999.93 (12)
C2—C8—C7120.8 (3)C2—P1—C9100.83 (13)
C2—C8—H81119.3
C2—P1—C1—C1i174.53 (18)C7—C5—C6—F2160.7 (3)
C9—P1—C1—C1i71.1 (2)C4—C5—C6—F3−146.1 (3)
C2—P1—C9—C10−25.8 (3)C7—C5—C6—F1−82.2 (3)
C1—P1—C2—C311.2 (3)C7—C5—C6—F336.0 (4)
C9—P1—C2—C3113.9 (2)C5—C7—C8—C21.4 (5)
C1—P1—C2—C8−171.8 (2)P1—C9—C10—C11−178.7 (2)
C9—P1—C2—C8−69.1 (2)C15—C9—C10—C110.4 (4)
C1—P1—C9—C15−100.4 (2)P1—C9—C15—C14177.9 (2)
C1—P1—C9—C1078.8 (3)C10—C9—C15—C14−1.3 (4)
C2—P1—C9—C15155.1 (2)C9—C10—C11—C120.5 (5)
P1—C1—C1i—P1i179.98 (16)C10—C11—C12—C13−179.7 (4)
P1—C2—C3—C4176.8 (2)C10—C11—C12—C14−0.6 (5)
C3—C2—C8—C7−1.1 (4)C11—C12—C13—F4−47.9 (5)
C8—C2—C3—C4−0.1 (4)C11—C12—C13—F5−165.0 (4)
P1—C2—C8—C7−178.4 (2)C11—C12—C13—F674.1 (5)
C2—C3—C4—C51.1 (4)C14—C12—C13—F4133.0 (4)
C3—C4—C5—C7−0.8 (4)C14—C12—C13—F515.8 (6)
C3—C4—C5—C6−178.7 (3)C14—C12—C13—F6−105.0 (5)
C4—C5—C6—F195.7 (4)C11—C12—C14—C15−0.3 (5)
C4—C5—C6—F2−21.5 (4)C13—C12—C14—C15178.8 (3)
C4—C5—C7—C8−0.4 (4)C12—C14—C15—C91.3 (5)
C6—C5—C7—C8177.5 (3)
Symmetry codes: (i) −x+2, −y+2, −z.
Table 1
Comparison of structural parameters (Å, °) for R2PCH2CH2PR2 top
RC-P-CΣ C-P-CP-CethylP-CR
p-Ph-CF3a100.79, 102.15,99.96302.901.8541.838
Phb100.219,102.369,101.047303.641.8441.832
p-Ph-CH3c98.668,101.864,102.985303.521.8491.821
p-Ph-CH2CH3d99.719,102.754,101.37303.841.851.83
CH3e98.869,99.665,98.872297.31.8481.836
CH2CH3e99.272,99.491,100.206298.51.8451.843
CH(CH3)2e101.184,100.805,102.235304.21.861.86
C(CH3)3f100.990,103.197,110.350314.51.861.89
Notes: (a) This work; (b) Tiekink (2001); (c) Zeller et al. (2003); (d) Zeller & Hunter (2004); (e) Bruckmann & Kruger (1997); (f) Eisentrager et al. (2003).
Acknowledgements top

RST acknowledges the Small Molecule X-ray Crystallography Summer School hosted by Professor Arnold Rheingold at the University of California – San Diego and the University of Wisconsin – Stevens Point Letters and Science Foundation and Chemistry Department.

references
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