5-(1H-Indol-3-yl)-1-phenyl­pent-4-ene-1,3-dione

The title mol­ecule, C₁₉H₁₅NO₂, exists in the enolized form and displays a strong intramolecular hydrogen bond. The structure supports the hypothesis that the conjugation in the mol­ecule is a determining factor for the position of the enol H atom. The packing of the mol­ecules is dominated by weak N—H...C and C—H...C interactions.

Key indicators

• Single-crystal X-ray study
• T = 105 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.037
• wR factor = 0.097
• Data-to-parameter ratio = 11.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



ABSMU_01  Alert C The ratio of given/expected absorption coefficient lies
          outside the range 0.99 <> 1.01
          Calculated value of mu =     0.088
          Value of mu given      =     0.090

STRVAL_01
         From the CIF: _refine_ls_abs_structure_Flack   -1.800
         From the CIF: _refine_ls_abs_structure_Flack_su    1.400
           Alert C Flack parameter is too small

PLAT_420  Alert C D-H Without Acceptor       N      -   H(1N)             ?

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           27.00
         From the CIF: _reflns_number_total               3044
         Count of symmetry unique reflns         1570
         Completeness (_total/calc)            193.89%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured      1474
         Fraction of Friedel pairs measured     0.939
         Are heavy atom types Z>Si present           no
          ALERT: MoKa measured Friedel data cannot be used to
                 determine absolute structure in a light-atom
                 study EXCEPT under VERY special conditions.
                 It is preferred that Friedel data is merged in such cases.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 3 Alert Level C = Please check

---

S1. Comment

The 5-(1H-indol-3-yl)-1-phenyl-pent-4-ene-1,3-dione (IPPD) molecule, (I), depicted in Fig. 1, is essentially planar as a result of the conjugation throughout the pentene chain. The largest deviation (observed for the O1 atom) from the least-squares plane of all non-hydrogen atoms is less than 0.21 Å; the mean deviation for all non-hydrogen atoms from this plane is less than 0.06 Å. The dihedral angle formed by the planes of the phenyl and the indolyl groups is 2.7 (1)°.

The distance of 2.498 (2) Å between the O1 and O2 atoms indicates a strong intramolecular hydrogen bond. Even though the enol hydrogen atom appears to be closer to O2, the difference between the distances to two oxygen atoms [H200—O2 1.20 (5) and H200—O1 1.37 (5) Å] is almost within experimental error. However, a statistically more significant difference in the O1—C7 and O2—C9 bond lengths [1.285 (3) and 1.320 (3) Å, respectively] points in the same direction, and is in a good agreement with the observation that the enol hydrogen atom is more tightly bonded to the O2 than to the O1 atom. This finding is in accordance with the principle of the longest possible conjugation in the molecule, as observed in several related compounds (Arrieta & Mostad, 2001; Arrieta & Mostad, 2002a; Arrieta & Mostad, 2002b) The details of the geometry of the intramolecular hydrogen bond and of the intermolecular short contacts (see below) are given in Table 2.

The crystal structure of the present compound is quite similar to that of 1,5-diphenylpent-4-ene-1,3-dione in that the molecules form layers normal to the longest unit cell axis (Arrieta & Mostad, 2002b). The contacts between the layers involve the atoms of phenyl and indolyl rings, the shortest distances being 3.07 (3) Å for H3···C15^v [symmetry code (v): 1.5 − x, y, z + 0.5] and 3.02 (3) Å for H16···C2^vi [symmetry code (vi): 2 − x, 1 − y, −0.5 + z]. Each molecule within the layer is in contact with six neighbours as illustrated in Fig 3. The shortest intermolecular distance of 2.50 (3) Å is found between the H1N and C13D atoms [symmetry code (D): x − 0.5, −y, z]. The dihedral angles formed by the planes of the aromatic units in neighbouring molecules are 56.8 (1)° for the phenyl rings and 55.4 (1)° for the indolyl rings. This packing mode, where the neigbouring aromatic rings form the angles of 70±20° to each other and a C—H bond in one ring is pointing towards the π-electrons of the other, is repeatedly encountered in crystal structures of similar molecules (Mostad, 1994; Arrieta & Mostad, 2002a; Arrieta & Mostad, 2002b).

S2. Experimental

The compound was synthesized by condensation of benzoylacetone with 1H-indol-3-carbaldehyde according to a known procedure (Arrieta et al., 1992). Melting point 479–480 K (ethanol). The crystals used in the X-ray experiments were recrystallized from a mixture of ethanol/acetone (10:1).

S3. Refinement

All hydrogen atoms were located from the difference Fourier map and refined in an isotropic approximation. The C—H distances are in the range 0.87–1.02 Å; N—H is found to be 0.85 (5) Å.

As one would expect, due to the lack of anomalous scatterers the absolute structure determination (Flack, 1983) was inconclusive.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXL97; software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The IPPD molecule, showing the atom-numberingscheme, with displacement ellipsoids drawn at the 50% probability level.
	Fig. 2. The packing of IPPD molecules in the crystal, viewed down the b axis.
	Fig. 3. The interaction between neighbouring molecules in the layers of the crystal structure of IPPD. [Symmetry codes: (A) 0.5 + x, 2 − y, z; (B) 0.5 + x, 1 − y, z; (C) 0.5 + x, −y, z; (D) x − 0.5, −y, z; (E) x − 0.5, 1 − y, z; (F) x − 0.5, 2 − y, z.]

1-phenyl-5-(3-indolyl)-pent-4-ene-1,3-dione

Crystal data

C19H15NO2	Dx = 1.354 Mg m^−3
Mr = 289.31	Melting point: 480 K
Orthorhombic, Pca21	Mo Kα radiation, λ = 0.71073 Å
a = 7.6712 (15) Å	Cell parameters from 6355 reflections
b = 5.6251 (11) Å	θ = 2.0–27.0°
c = 32.773 (7) Å	µ = 0.09 mm^−1
V = 1414.2 (5) Å^3	T = 105 K
Z = 4	Plates, red
F(000) = 608	0.4 × 0.4 × 0.15 mm

Data collection

Bruker SMART diffractometer	3044 independent reflections
Radiation source: fine-focus sealed tube	2508 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.052
Detector resolution: 8 pixels mm^-1	θmax = 27.0°, θmin = 1.2°
ω scans	h = −9→9
Absorption correction: multi-scan (SADABS; Sheldrick, 1997)	k = −7→7
Tmin = 0.876, Tmax = 0.965	l = −41→41
14386 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.037	All H-atom parameters refined
wR(F^2) = 0.097	w = 1/[σ^2(Fo^2) + (0.0532P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max = 0.002
3044 reflections	Δρmax = 0.16 e Å^−3
259 parameters	Δρmin = −0.19 e Å^−3
1 restraint	Absolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −1.8 (14)

Special details

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
O1	0.8753 (3)	1.0093 (3)	0.94133 (5)	0.0370 (4)
O2	0.9308 (2)	0.8529 (3)	0.87118 (5)	0.0333 (4)
H200	0.928 (6)	0.964 (8)	0.9023 (14)	0.102 (14)*
N	0.7701 (2)	−0.0183 (3)	0.74798 (6)	0.0247 (4)
H1N	0.715 (3)	−0.145 (5)	0.7420 (7)	0.033 (7)*
C1	0.7848 (3)	0.9531 (4)	1.02260 (7)	0.0238 (5)
H1	0.847 (3)	1.094 (4)	1.0131 (7)	0.026 (6)*
C2	0.7326 (3)	0.9276 (4)	1.06316 (7)	0.0267 (5)
H2	0.753 (4)	1.059 (5)	1.0831 (8)	0.033 (7)*
C3	0.6404 (3)	0.7276 (4)	1.07519 (7)	0.0273 (5)
H3	0.603 (3)	0.704 (4)	1.1015 (8)	0.021 (6)*
C4	0.5974 (3)	0.5543 (4)	1.04686 (7)	0.0276 (5)
H4	0.522 (3)	0.414 (4)	1.0554 (6)	0.018 (6)*
C5	0.6484 (3)	0.5789 (4)	1.00636 (7)	0.0250 (5)
H5	0.620 (3)	0.465 (3)	0.9896 (6)	0.006 (5)*
C6	0.7435 (3)	0.7790 (4)	0.99375 (6)	0.0229 (5)
C7	0.8039 (3)	0.8105 (4)	0.95101 (7)	0.0247 (5)
C8	0.7890 (3)	0.6264 (4)	0.92177 (7)	0.0269 (5)
H8	0.743 (3)	0.482 (5)	0.9298 (8)	0.035 (7)*
C9	0.8509 (3)	0.6554 (4)	0.88231 (7)	0.0251 (5)
C10	0.8283 (3)	0.4692 (4)	0.85197 (7)	0.0272 (5)
H10	0.763 (3)	0.328 (5)	0.8631 (7)	0.032 (7)*
C11	0.8859 (3)	0.4849 (4)	0.81351 (7)	0.0230 (4)
H11	0.944 (3)	0.627 (4)	0.8060 (7)	0.024 (6)*
C12	0.8584 (3)	0.3088 (4)	0.78176 (7)	0.0227 (4)
C13	0.9169 (3)	0.3255 (3)	0.73982 (6)	0.0195 (4)
C14	1.0112 (3)	0.4936 (4)	0.71737 (7)	0.0212 (4)
H14	1.040 (3)	0.646 (5)	0.7292 (8)	0.036 (7)*
C15	1.0470 (3)	0.4501 (4)	0.67646 (7)	0.0240 (5)
H15	1.105 (3)	0.563 (5)	0.6603 (8)	0.034 (7)*
C16	0.9867 (3)	0.2412 (4)	0.65718 (8)	0.0258 (5)
H16	1.013 (3)	0.213 (4)	0.6295 (8)	0.027 (6)*
C17	0.8917 (3)	0.0729 (4)	0.67845 (7)	0.0233 (5)
H17	0.852 (3)	−0.059 (4)	0.6639 (7)	0.025 (6)*
C18	0.8577 (3)	0.1163 (3)	0.71976 (7)	0.0211 (4)
C19	0.7689 (3)	0.0959 (4)	0.78478 (7)	0.0247 (5)
H19	0.719 (3)	0.020 (4)	0.8097 (8)	0.022 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0559 (11)	0.0283 (8)	0.0266 (9)	−0.0120 (8)	0.0054 (8)	−0.0016 (7)
O2	0.0466 (10)	0.0276 (8)	0.0258 (9)	−0.0067 (8)	0.0053 (8)	−0.0019 (7)
N	0.0232 (10)	0.0192 (8)	0.0315 (11)	−0.0025 (7)	−0.0018 (8)	−0.0018 (8)
C1	0.0259 (12)	0.0203 (10)	0.0252 (12)	0.0014 (9)	0.0005 (9)	0.0000 (8)
C2	0.0273 (12)	0.0269 (11)	0.0261 (12)	0.0040 (9)	−0.0012 (10)	−0.0055 (9)
C3	0.0293 (12)	0.0310 (12)	0.0217 (11)	0.0047 (10)	0.0012 (10)	0.0021 (10)
C4	0.0291 (12)	0.0256 (11)	0.0281 (12)	0.0013 (10)	−0.0003 (10)	0.0026 (9)
C5	0.0274 (12)	0.0233 (11)	0.0242 (12)	−0.0010 (9)	−0.0030 (10)	−0.0050 (9)
C6	0.0230 (10)	0.0235 (10)	0.0222 (11)	0.0047 (9)	−0.0008 (9)	0.0000 (8)
C7	0.0251 (12)	0.0248 (11)	0.0243 (11)	0.0005 (9)	−0.0011 (9)	0.0010 (9)
C8	0.0319 (13)	0.0231 (11)	0.0258 (12)	−0.0048 (9)	0.0021 (9)	−0.0003 (9)
C9	0.0262 (11)	0.0254 (10)	0.0238 (12)	0.0033 (9)	−0.0009 (9)	−0.0017 (9)
C10	0.0270 (11)	0.0269 (12)	0.0276 (13)	−0.0019 (9)	−0.0001 (10)	0.0013 (9)
C11	0.0221 (11)	0.0211 (10)	0.0258 (11)	0.0027 (8)	−0.0014 (9)	−0.0009 (9)
C12	0.0203 (10)	0.0209 (9)	0.0269 (11)	0.0029 (8)	−0.0032 (9)	−0.0002 (9)
C13	0.0174 (9)	0.0186 (9)	0.0226 (11)	0.0039 (7)	−0.0025 (9)	−0.0022 (8)
C14	0.0173 (10)	0.0185 (9)	0.0277 (11)	0.0016 (8)	−0.0018 (9)	0.0000 (9)
C15	0.0200 (10)	0.0247 (11)	0.0274 (12)	0.0013 (9)	0.0018 (9)	0.0026 (9)
C16	0.0222 (11)	0.0314 (12)	0.0237 (11)	0.0040 (10)	0.0004 (9)	−0.0036 (9)
C17	0.0209 (11)	0.0226 (10)	0.0266 (12)	0.0030 (8)	−0.0034 (9)	−0.0059 (9)
C18	0.0179 (10)	0.0173 (9)	0.0279 (12)	0.0032 (7)	−0.0028 (9)	0.0000 (8)
C19	0.0218 (11)	0.0251 (10)	0.0272 (13)	0.0032 (9)	0.0013 (10)	0.0037 (9)

Geometric parameters (Å, º)

O1—C7	1.285 (3)	C8—C9	1.387 (3)
O1—H200	1.37 (5)	C8—H8	0.93 (3)
O2—C9	1.320 (3)	C9—C10	1.455 (3)
O2—H200	1.20 (5)	C10—C11	1.339 (3)
N—C18	1.371 (3)	C10—H10	1.01 (3)
N—C19	1.367 (3)	C11—C12	1.452 (3)
N—H1N	0.85 (3)	C11—H11	0.95 (3)
C1—C2	1.396 (3)	C12—C13	1.449 (3)
C1—C6	1.397 (3)	C12—C19	1.384 (3)
C1—H1	0.98 (3)	C13—C14	1.400 (3)
C2—C3	1.386 (3)	C13—C18	1.422 (3)
C2—H2	1.00 (3)	C14—C15	1.390 (3)
C3—C4	1.386 (3)	C14—H14	0.97 (3)
C3—H3	0.92 (2)	C15—C16	1.412 (3)
C4—C5	1.391 (3)	C15—H15	0.94 (3)
C4—H4	1.02 (2)	C16—C17	1.383 (3)
C5—C6	1.404 (3)	C16—H16	0.94 (3)
C5—H5	0.87 (2)	C17—C18	1.400 (3)
C6—C7	1.486 (3)	C17—H17	0.93 (2)
C7—C8	1.415 (3)	C19—H19	1.00 (2)
C7—O1—H200	101.4 (19)	C8—C9—C10	120.8 (2)
C9—O2—H200	101 (2)	C11—C10—C9	123.8 (2)
C19—N—C18	109.81 (18)	C11—C10—H10	123.9 (15)
C19—N—H1N	126.4 (17)	C9—C10—H10	112.3 (14)
C18—N—H1N	123.4 (17)	C10—C11—C12	125.6 (2)
C2—C1—C6	120.5 (2)	C10—C11—H11	117.2 (14)
C2—C1—H1	121.8 (14)	C12—C11—H11	117.2 (14)
C6—C1—H1	117.7 (14)	C19—C12—C13	106.10 (19)
C3—C2—C1	120.1 (2)	C19—C12—C11	127.7 (2)
C3—C2—H2	119.6 (15)	C13—C12—C11	126.21 (19)
C1—C2—H2	120.1 (16)	C14—C13—C18	118.8 (2)
C4—C3—C2	120.1 (2)	C14—C13—C12	134.62 (19)
C4—C3—H3	116.8 (15)	C18—C13—C12	106.62 (19)
C2—C3—H3	123.1 (15)	C15—C14—C13	119.4 (2)
C3—C4—C5	120.2 (2)	C15—C14—H14	119.8 (15)
C3—C4—H4	119.8 (12)	C13—C14—H14	120.5 (15)
C5—C4—H4	119.9 (12)	C14—C15—C16	120.9 (2)
C4—C5—C6	120.4 (2)	C14—C15—H15	121.4 (17)
C4—C5—H5	117.4 (14)	C16—C15—H15	117.6 (17)
C6—C5—H5	122.2 (14)	C17—C16—C15	121.1 (2)
C1—C6—C5	118.7 (2)	C17—C16—H16	119.0 (14)
C1—C6—C7	118.92 (19)	C15—C16—H16	119.8 (15)
C5—C6—C7	122.3 (2)	C16—C17—C18	117.8 (2)
O1—C7—C8	120.3 (2)	C16—C17—H17	117.2 (15)
O1—C7—C6	117.98 (19)	C18—C17—H17	125.0 (15)
C8—C7—C6	121.73 (19)	N—C18—C17	130.31 (19)
C9—C8—C7	121.2 (2)	N—C18—C13	107.56 (19)
C9—C8—H8	119.9 (17)	C17—C18—C13	122.1 (2)
C7—C8—H8	118.8 (17)	N—C19—C12	109.9 (2)
O2—C9—C8	121.02 (19)	N—C19—H19	121.6 (14)
O2—C9—C10	118.20 (19)	C12—C19—H19	128.2 (14)
C6—C1—C2—C3	0.5 (3)	C19—C12—C13—C14	179.6 (2)
C1—C2—C3—C4	−1.0 (4)	C11—C12—C13—C14	1.0 (4)
C2—C3—C4—C5	0.8 (4)	C19—C12—C13—C18	−0.1 (2)
C3—C4—C5—C6	−0.1 (4)	C11—C12—C13—C18	−178.71 (19)
C2—C1—C6—C5	0.2 (3)	C18—C13—C14—C15	−1.1 (3)
C2—C1—C6—C7	−178.96 (19)	C12—C13—C14—C15	179.3 (2)
C4—C5—C6—C1	−0.4 (3)	C13—C14—C15—C16	1.2 (3)
C4—C5—C6—C7	178.7 (2)	C14—C15—C16—C17	−0.6 (3)
C1—C6—C7—O1	−7.5 (3)	C15—C16—C17—C18	−0.2 (3)
C5—C6—C7—O1	173.4 (2)	C19—N—C18—C17	−179.8 (2)
C1—C6—C7—C8	170.7 (2)	C19—N—C18—C13	0.7 (2)
C5—C6—C7—C8	−8.4 (3)	C16—C17—C18—N	−179.1 (2)
O1—C7—C8—C9	0.2 (3)	C16—C17—C18—C13	0.2 (3)
C6—C7—C8—C9	−177.9 (2)	C14—C13—C18—N	179.89 (17)
C7—C8—C9—O2	2.2 (3)	C12—C13—C18—N	−0.4 (2)
C7—C8—C9—C10	−177.3 (2)	C14—C13—C18—C17	0.4 (3)
O2—C9—C10—C11	1.0 (3)	C12—C13—C18—C17	−179.87 (19)
C8—C9—C10—C11	−179.5 (2)	C18—N—C19—C12	−0.8 (2)
C9—C10—C11—C12	−176.7 (2)	C13—C12—C19—N	0.6 (2)
C10—C11—C12—C19	0.4 (4)	C11—C12—C19—N	179.1 (2)
C10—C11—C12—C13	178.7 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···C5^i	0.98 (3)	2.96 (3)	3.872 (3)	155.4 (19)
C4—H4···C1^ii	1.02 (2)	2.95 (2)	3.812 (3)	142.4 (15)
C14—H14···N^iii	0.97 (3)	2.87 (3)	3.459 (3)	120.1 (19)
N—H1N···C13^iv	0.85 (3)	2.50 (3)	3.225 (3)	143 (2)
C3—H3···C15^v	0.92 (2)	3.07 (3)	3.939 (3)	159.7 (18)
C16—H16···C2^vi	0.94 (3)	3.02 (3)	3.877 (3)	150.9 (19)
O2—H200···O1	1.20 (5)	1.37 (5)	2.498 (2)	154 (4)

Symmetry codes: (i) x+1/2, −y+2, z; (ii) x−1/2, −y+1, z; (iii) x, y+1, z; (iv) x−1/2, −y, z; (v) −x+3/2, y, z+1/2; (vi) −x+2, −y+1, z−1/2.