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The P atom of the title compound, C18H16FN4P, has a slightly distorted tetrahedral geometry. The P-N bond lengths range from 1.671 (3) to 1.680 (3) Å, while the P=N bond is 1.517 (3) Å. The pyrrolyl groups are arranged around the P atom in a chiral propeller-like geometry.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101013877/fr1341sup1.cif
Contains datablocks sb101, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270101013877/fr1341Isup2.hkl
Contains datablock I

CCDC reference: 175106

Comment top

We have recently reported that iminophosphoranes of the type Cl3PNAr (Ar is 2-fluorophenyl) are important main-group examples of well defined carbodiimide metathesis catalysts (Bell et al., 2000). It is believed that these catalysts follow an addition–elimination pathway for double-bond metathesis. We produced pyrrolyl derivatives of the iminophosphoranes in an effort to rule out the possibility of HCl-mediated metathesis pathways that might arise from the decomposition of trichloroiminophosphoranes. Selection of the pyrrolyl moiety as a chloride replacement was prompted by Petersen's discussion of tripyrrolylphosphorus ligands (Moloy & Petersen, 1995). In particular, pyrrolyl is π-acidic, which allows replacement of chlorine without loss of electrophilicity at the phosphorus center, believed to be an important factor in the carbodiimide metatheses.

The structure determination of the title compound, (I), was undertaken to study the effect of substitution on significant features of the phosphorus center. We report herein the first example of a tripyrrolyl derivative of an iminophosphorane. The only previous example of a pyrrolyl derivative is bispyrrolylcyclophosphazene (Craig et al., 1987). A notable aspect of the crystal structure reported here is the short PN bond length [1.517 (3) Å], which is significantly shorter than in bispyrrolylcyclophosphazene [1.583 (6) Å]. It is important to note that the PN bond length is similar to chlorine-derivatized hydrocarbyliminophosphoranes ranging from 1.505 (3) (Antipin et al., 1985) to 1.557 (2) Å (Belaj, 1996).

P—N bond length has been correlated with the orbital electronegativity of the phosphorus substituents (Bullen & Tucker, 1972). The comparable PN bond length of the trichloro- and tripyrrolyliminophosphoranes indicates a similar electronegativity of the phosphorus substituents.

The P atom is slightly distorted from tetrahedral geometry, with the bond angles around it varying from 101.93 (16) to 117.74 (17)°, the average value being 109.1 (2)°. The pyrrolyl groups make interplanar angles of 45.9 (3), 55.0 (3) and 63.4 (2)° with the 2-fluorophenyl ring. The P atom has chirality due to the propeller-like arrangement of the pyrrolyl rings, although no conclusion can be made about the absolute configuration as the Friedel pairs were not collected for this structure.

Related literature top

For related literature, see: Antipin et al. (1985); Belaj (1996); Bell et al. (2000); Bullen & Tucker (1972); Craig et al. (1987); Moloy & Petersen (1995).

Experimental top

Potassium pyrrolide (0.518 g, 4.93 mmol) was slowly added to a vigorously stirred solution of Cl3PNAr (0.405 g, 1.643 mmol) in hexanes (45 ml) at 195 K. The mixture was stirred for 30 min at 195 K and was then warmed to room temperature and stirred for an additional 14 h. Filtration yielded a colorless liquid that was reduced to 15 ml and cooled to 238 K. The precipitate was removed by filtration and the filtrate was again reduced in volume and cooled to yield colorless crystals (yield: 0.231 g, 41.5%). 1H NMR (300 MHz, d8-toluene, p.p.m.): δ 6.79 (m, 4H, aryl), 6.67 (m, 6H, pyrrolyl), 6.08 (m, 6H, pyrrolyl); 31P NMR (121 MHz, d8-toluene, p.p.m.): δ -32.4.

Refinement top

H atoms were calculated in idealized isotropic positions [C—H = 0.94 Å and Uiso(H) = 1.2Uiso(C)].

Computing details top

Data collection: P3 Diffractometer Control Program (Siemens, 1990); cell refinement: P3 Diffractometer Control Program; data reduction: P3 Diffractometer Control Program; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997).

Figures top
[Figure 1] Fig. 1. The structure of the title compound with 50% probability displacement ellipsoids and the atom-numbering scheme.
(I) top
Crystal data top
C18H16FN4PF(000) = 352
Mr = 338.32Dx = 1.328 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
a = 7.6950 (15) ÅCell parameters from 24 reflections
b = 14.828 (3) Åθ = 9–13°
c = 8.0060 (16) ŵ = 0.18 mm1
β = 112.11 (3)°T = 206 K
V = 846.3 (3) Å3Plate, colorless
Z = 20.40 × 0.30 × 0.05 mm
Data collection top
Siemens P3
diffractometer
1343 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.046
Graphite monochromatorθmax = 25.0°, θmin = 2.7°
ω scansh = 39
Absorption correction: ψ scan
(North et al., 1968)
k = 017
Tmin = 0.932, Tmax = 0.991l = 99
2400 measured reflections3 standard reflections every 197 reflections
1572 independent reflections intensity decay: 1%
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.038 w = 1/[σ2(Fo2) + (0.0413P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.089(Δ/σ)max = 0.001
S = 1.10Δρmax = 0.24 e Å3
1572 reflectionsΔρmin = 0.23 e Å3
218 parametersExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraintExtinction coefficient: 0.011 (3)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983)
Secondary atom site location: difference Fourier mapAbsolute structure parameter: 0.12 (16)
Crystal data top
C18H16FN4PV = 846.3 (3) Å3
Mr = 338.32Z = 2
Monoclinic, P21Mo Kα radiation
a = 7.6950 (15) ŵ = 0.18 mm1
b = 14.828 (3) ÅT = 206 K
c = 8.0060 (16) Å0.40 × 0.30 × 0.05 mm
β = 112.11 (3)°
Data collection top
Siemens P3
diffractometer
1343 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.046
Tmin = 0.932, Tmax = 0.9913 standard reflections every 197 reflections
2400 measured reflections intensity decay: 1%
1572 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.038H-atom parameters constrained
wR(F2) = 0.089Δρmax = 0.24 e Å3
S = 1.10Δρmin = 0.23 e Å3
1572 reflectionsAbsolute structure: Flack (1983)
218 parametersAbsolute structure parameter: 0.12 (16)
1 restraint
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
P10.80813 (13)0.52138 (7)0.32311 (11)0.0272 (2)
F11.1997 (3)0.5907 (2)0.5610 (3)0.0585 (8)
N10.8647 (5)0.6090 (2)0.2598 (5)0.0375 (9)
C11.0309 (6)0.6524 (3)0.2756 (5)0.0301 (9)
N20.6143 (5)0.4788 (2)0.1634 (4)0.0352 (8)
C21.1985 (6)0.6450 (3)0.4234 (6)0.0387 (10)
N30.9599 (5)0.4351 (2)0.3703 (4)0.0295 (7)
C31.3597 (6)0.6884 (3)0.4380 (7)0.0466 (11)
H3A1.47060.67900.53930.056*
N40.7442 (4)0.5276 (3)0.5005 (3)0.0307 (7)
C41.3581 (7)0.7459 (3)0.3025 (7)0.0543 (12)
H4A1.46750.77700.31070.065*
C51.1928 (7)0.7574 (3)0.1537 (6)0.0488 (12)
H5A1.19040.79680.06080.059*
C61.0324 (7)0.7119 (3)0.1406 (6)0.0399 (10)
H6A0.92170.72090.03900.048*
C70.5741 (7)0.3886 (3)0.1217 (6)0.0428 (11)
H7A0.65700.34010.16870.051*
C80.3947 (7)0.3820 (4)0.0014 (6)0.0557 (14)
H8A0.33190.32860.05120.067*
C90.3202 (6)0.4697 (4)0.0300 (6)0.0562 (14)
H9A0.19760.48500.10720.067*
C100.4526 (5)0.5281 (4)0.0682 (5)0.0458 (11)
H10A0.43880.59100.07220.055*
C110.9916 (6)0.3684 (3)0.5000 (6)0.0355 (9)
H11A0.93530.36470.58560.043*
C121.1172 (6)0.3097 (3)0.4816 (6)0.0414 (10)
H12A1.16410.25800.55230.050*
C131.1657 (6)0.3396 (3)0.3375 (6)0.0403 (10)
H13A1.25010.31100.29490.048*
C141.0706 (6)0.4157 (3)0.2716 (6)0.0362 (10)
H14A1.07750.45000.17550.043*
C150.8419 (6)0.5732 (3)0.6622 (5)0.0384 (10)
H15A0.94490.61190.68410.046*
C160.7627 (7)0.5519 (3)0.7800 (6)0.0464 (12)
H16A0.80060.57350.89880.056*
C170.6130 (7)0.4917 (3)0.6963 (6)0.0442 (11)
H17A0.53450.46590.74920.053*
C180.6034 (6)0.4783 (3)0.5283 (5)0.0366 (9)
H18A0.51530.44140.44210.044*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
P10.0224 (5)0.0319 (5)0.0272 (4)0.0011 (5)0.0093 (4)0.0009 (5)
F10.0392 (15)0.075 (2)0.0531 (15)0.0035 (15)0.0085 (12)0.0259 (15)
N10.0308 (19)0.038 (2)0.0446 (19)0.0005 (17)0.0156 (16)0.0107 (16)
C10.028 (2)0.028 (2)0.036 (2)0.0041 (18)0.0139 (18)0.0031 (16)
N20.0286 (17)0.046 (2)0.0295 (16)0.0033 (17)0.0095 (14)0.0029 (15)
C20.036 (2)0.037 (2)0.043 (2)0.000 (2)0.015 (2)0.0051 (18)
N30.0287 (17)0.0318 (18)0.0315 (16)0.0001 (16)0.0154 (15)0.0033 (15)
C30.031 (2)0.038 (2)0.061 (3)0.005 (2)0.007 (2)0.001 (2)
N40.0316 (16)0.0325 (17)0.0294 (14)0.0002 (19)0.0132 (12)0.0038 (17)
C40.041 (3)0.044 (3)0.084 (3)0.007 (2)0.030 (3)0.003 (3)
C50.052 (3)0.040 (3)0.064 (3)0.001 (2)0.032 (3)0.016 (2)
C60.044 (2)0.033 (2)0.049 (2)0.006 (2)0.024 (2)0.0068 (19)
C70.044 (3)0.048 (3)0.042 (2)0.017 (2)0.021 (2)0.009 (2)
C80.049 (3)0.077 (4)0.043 (3)0.031 (3)0.020 (2)0.021 (3)
C90.023 (2)0.100 (4)0.040 (2)0.007 (3)0.0056 (19)0.006 (3)
C100.031 (2)0.066 (3)0.039 (2)0.008 (3)0.0103 (17)0.002 (3)
C110.036 (2)0.037 (2)0.0367 (19)0.002 (2)0.0167 (17)0.0072 (18)
C120.036 (2)0.032 (2)0.054 (3)0.004 (2)0.015 (2)0.007 (2)
C130.032 (2)0.037 (2)0.056 (3)0.000 (2)0.021 (2)0.009 (2)
C140.035 (2)0.041 (3)0.041 (2)0.001 (2)0.023 (2)0.0016 (19)
C150.042 (2)0.037 (2)0.031 (2)0.003 (2)0.0084 (18)0.0023 (18)
C160.057 (3)0.054 (3)0.031 (2)0.006 (2)0.020 (2)0.0025 (18)
C170.054 (3)0.042 (2)0.049 (2)0.004 (2)0.034 (2)0.003 (2)
C180.035 (2)0.037 (2)0.043 (2)0.007 (2)0.0212 (19)0.0022 (19)
Geometric parameters (Å, º) top
P1—N11.517 (3)C7—C81.357 (6)
P1—N41.671 (3)C7—H7A0.9400
P1—N31.676 (3)C8—C91.406 (8)
P1—N21.680 (3)C8—H8A0.9400
F1—C21.361 (5)C9—C101.343 (7)
N1—C11.394 (5)C9—H9A0.9400
C1—C21.388 (6)C10—H10A0.9400
C1—C61.398 (5)C11—C121.350 (6)
N2—C71.386 (6)C11—H11A0.9400
N2—C101.397 (6)C12—C131.411 (6)
C2—C31.362 (6)C12—H12A0.9400
N3—C111.388 (5)C13—C141.341 (6)
N3—C141.393 (5)C13—H13A0.9400
C3—C41.377 (7)C14—H14A0.9400
C3—H3A0.9400C15—C161.339 (6)
N4—C181.392 (5)C15—H15A0.9400
N4—C151.402 (5)C16—C171.411 (6)
C4—C51.388 (7)C16—H16A0.9400
C4—H4A0.9400C17—C181.334 (5)
C5—C61.376 (6)C17—H17A0.9400
C5—H5A0.9400C18—H18A0.9400
C6—H6A0.9400
N1—P1—N4116.7 (2)C8—C7—H7A125.8
N1—P1—N3117.74 (17)N2—C7—H7A125.8
N4—P1—N3104.68 (16)C7—C8—C9107.3 (5)
N1—P1—N2110.59 (19)C7—C8—H8A126.3
N4—P1—N2101.93 (16)C9—C8—H8A126.3
N3—P1—N2103.22 (18)C10—C9—C8108.9 (4)
C1—N1—P1137.2 (3)C10—C9—H9A125.6
C2—C1—N1124.5 (4)C8—C9—H9A125.6
C2—C1—C6115.7 (4)C9—C10—N2107.8 (5)
N1—C1—C6119.7 (4)C9—C10—H10A126.1
C7—N2—C10107.6 (4)N2—C10—H10A126.1
C7—N2—P1126.9 (3)C12—C11—N3108.0 (4)
C10—N2—P1124.9 (3)C12—C11—H11A126.0
F1—C2—C3118.7 (4)N3—C11—H11A126.0
F1—C2—C1117.2 (4)C11—C12—C13107.9 (4)
C3—C2—C1124.1 (4)C11—C12—H12A126.1
C11—N3—C14107.7 (3)C13—C12—H12A126.1
C11—N3—P1128.6 (3)C14—C13—C12108.3 (4)
C14—N3—P1123.6 (3)C14—C13—H13A125.9
C2—C3—C4119.1 (4)C12—C13—H13A125.9
C2—C3—H3A120.4C13—C14—N3108.1 (4)
C4—C3—H3A120.4C13—C14—H14A126.0
C18—N4—C15106.5 (3)N3—C14—H14A126.0
C18—N4—P1127.0 (3)C16—C15—N4108.0 (4)
C15—N4—P1125.8 (3)C16—C15—H15A126.0
C3—C4—C5119.1 (4)N4—C15—H15A126.0
C3—C4—H4A120.5C15—C16—C17108.8 (4)
C5—C4—H4A120.5C15—C16—H16A125.6
C6—C5—C4120.8 (4)C17—C16—H16A125.6
C6—C5—H5A119.6C18—C17—C16107.4 (4)
C4—C5—H5A119.6C18—C17—H17A126.3
C5—C6—C1121.3 (4)C16—C17—H17A126.3
C5—C6—H6A119.4C17—C18—N4109.4 (4)
C1—C6—H6A119.4C17—C18—H18A125.3
C8—C7—N2108.4 (5)N4—C18—H18A125.3

Experimental details

Crystal data
Chemical formulaC18H16FN4P
Mr338.32
Crystal system, space groupMonoclinic, P21
Temperature (K)206
a, b, c (Å)7.6950 (15), 14.828 (3), 8.0060 (16)
β (°) 112.11 (3)
V3)846.3 (3)
Z2
Radiation typeMo Kα
µ (mm1)0.18
Crystal size (mm)0.40 × 0.30 × 0.05
Data collection
DiffractometerSiemens P3
diffractometer
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.932, 0.991
No. of measured, independent and
observed [I > 2σ(I)] reflections
2400, 1572, 1343
Rint0.046
(sin θ/λ)max1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.038, 0.089, 1.10
No. of reflections1572
No. of parameters218
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.24, 0.23
Absolute structureFlack (1983)
Absolute structure parameter0.12 (16)

Computer programs: P3 Diffractometer Control Program (Siemens, 1990), P3 Diffractometer Control Program, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997).

Selected geometric parameters (Å, º) top
P1—N11.517 (3)P1—N21.680 (3)
P1—N41.671 (3)F1—C21.361 (5)
P1—N31.676 (3)N1—C11.394 (5)
N1—P1—N4116.7 (2)N4—P1—N2101.93 (16)
N1—P1—N3117.74 (17)N3—P1—N2103.22 (18)
N4—P1—N3104.68 (16)C1—N1—P1137.2 (3)
N1—P1—N2110.59 (19)
 

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