Orthorhombic form of 6-phenylhex-5-ene-2,4-dione

The title compound, C₁₂H₁₂O₂, crystallizes in at least two polymorphic forms, one monoclinic and the other ortho­rhombic. In the orthorhombic polymorph, the enol group is asymmetric with the H atom bonded to the O atom closest to the most electronegative substituent, and the mol­ecule displays the longest possible conjugation. The molecular packing is dominated by weak C—H...O interactions.

Key indicators

• Single-crystal X-ray study
• T = 123 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.041
• wR factor = 0.137
• Data-to-parameter ratio = 14.2

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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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: SHELXTL (Bruker, 1998); software used to prepare material for publication: SHELXL97.

6-phenyl-hex-5-ene-2,3-dione

Crystal data

C12H12O2	Dx = 1.251 Mg m^−3
Mr = 188.22	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 1024 reflections
a = 8.9118 (18) Å	θ = 4.9–56.6°
b = 9.4953 (19) Å	µ = 0.08 mm^−1
c = 23.628 (5) Å	T = 123 K
V = 1999.4 (7) Å^3	Prismatic, yellow
Z = 8	0.5 × 0.5 × 0.5 mm
F(000) = 800

Data collection

Bruker SMART 1000 diffractometer	2117 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.022
Graphite monochromator	θmax = 28.3°, θmin = 1.7°
Detector resolution: 8 pixels mm^-1	h = −11→11
ω scans	k = −12→12
22303 measured reflections	l = −31→31
2484 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.137	All H-atom parameters refined
S = 1.12	w = 1/[σ^2(Fo^2) + (0.0786P)^2 + 0.3676P] where P = (Fo^2 + 2Fc^2)/3
2484 reflections	(Δ/σ)max = 0.001
175 parameters	Δρmax = 0.27 e Å^−3
0 restraints	Δρmin = −0.20 e Å^−3

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
O2	0.15763 (11)	0.41407 (11)	1.02601 (4)	0.0451 (3)
C5	0.35327 (14)	0.41508 (13)	0.95832 (5)	0.0329 (3)
O1	0.17570 (12)	0.26796 (11)	1.11420 (4)	0.0448 (3)
C7	0.32508 (14)	0.55492 (12)	0.86880 (5)	0.0306 (3)
C3	0.36973 (14)	0.27630 (13)	1.04732 (5)	0.0338 (3)
C12	0.23888 (15)	0.65810 (14)	0.84172 (5)	0.0356 (3)
C6	0.27959 (14)	0.50658 (13)	0.92530 (5)	0.0323 (3)
C4	0.29333 (14)	0.36701 (12)	1.01243 (5)	0.0310 (3)
C2	0.30470 (15)	0.22893 (12)	1.09945 (5)	0.0337 (3)
C11	0.27489 (15)	0.70378 (15)	0.78736 (5)	0.0377 (3)
C10	0.39557 (15)	0.64545 (14)	0.75881 (5)	0.0368 (3)
C8	0.44917 (15)	0.49877 (13)	0.83985 (5)	0.0341 (3)
C1	0.39099 (19)	0.13243 (15)	1.13747 (6)	0.0419 (3)
C9	0.48290 (15)	0.54290 (14)	0.78535 (5)	0.0371 (3)
H6	0.1842 (18)	0.5443 (17)	0.9381 (7)	0.041 (4)*
H9	0.5711 (19)	0.4992 (17)	0.7657 (7)	0.043 (4)*
H10	0.4183 (18)	0.6761 (17)	0.7205 (7)	0.044 (4)*
H8	0.5093 (19)	0.4269 (19)	0.8564 (7)	0.048 (4)*
H3	0.4672 (19)	0.2447 (17)	1.0373 (7)	0.045 (4)*
H11	0.2108 (18)	0.7779 (18)	0.7699 (7)	0.043 (4)*
H5	0.4498 (18)	0.3775 (17)	0.9478 (7)	0.042 (4)*
H12	0.1520 (19)	0.6994 (19)	0.8607 (7)	0.046 (4)*
H20	0.135 (3)	0.370 (2)	1.0631 (11)	0.088 (7)*
H1B	0.326 (3)	0.058 (3)	1.1518 (10)	0.084 (7)*
H1C	0.480 (3)	0.095 (2)	1.1227 (10)	0.087 (7)*
H1A	0.422 (3)	0.182 (3)	1.1705 (13)	0.110 (8)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O2	0.0438 (6)	0.0507 (6)	0.0409 (5)	0.0088 (4)	0.0110 (4)	0.0086 (4)
C5	0.0355 (6)	0.0370 (6)	0.0263 (5)	−0.0023 (5)	0.0014 (4)	−0.0010 (4)
O1	0.0500 (6)	0.0454 (6)	0.0390 (5)	−0.0015 (4)	0.0139 (4)	0.0056 (4)
C7	0.0360 (6)	0.0296 (5)	0.0261 (5)	−0.0035 (4)	−0.0026 (4)	−0.0009 (4)
C3	0.0363 (6)	0.0384 (6)	0.0269 (6)	−0.0022 (5)	0.0012 (5)	0.0003 (4)
C12	0.0370 (6)	0.0380 (6)	0.0317 (6)	0.0026 (5)	−0.0022 (5)	−0.0011 (5)
C6	0.0367 (6)	0.0327 (6)	0.0273 (5)	−0.0022 (5)	0.0008 (4)	−0.0018 (4)
C4	0.0350 (6)	0.0310 (6)	0.0270 (5)	−0.0047 (4)	0.0009 (4)	−0.0035 (4)
C2	0.0446 (6)	0.0292 (6)	0.0272 (5)	−0.0086 (5)	0.0010 (5)	−0.0036 (4)
C11	0.0411 (7)	0.0400 (7)	0.0320 (6)	0.0003 (5)	−0.0080 (5)	0.0035 (5)
C10	0.0447 (7)	0.0390 (6)	0.0267 (6)	−0.0066 (5)	−0.0026 (5)	0.0009 (4)
C8	0.0376 (6)	0.0309 (6)	0.0340 (6)	0.0004 (5)	0.0007 (5)	0.0028 (4)
C1	0.0566 (8)	0.0410 (7)	0.0280 (6)	−0.0043 (6)	−0.0024 (6)	0.0019 (5)
C9	0.0413 (7)	0.0358 (6)	0.0341 (6)	−0.0015 (5)	0.0051 (5)	−0.0001 (5)

Geometric parameters (Å, º)

O2—C4	1.3286 (16)	C12—H12	0.976 (17)
O2—H20	0.99 (3)	C6—H6	0.971 (16)
C5—C6	1.3397 (17)	C2—C1	1.4960 (19)
C5—C4	1.4589 (16)	C11—C10	1.3851 (19)
C5—H5	0.964 (16)	C11—H11	0.996 (17)
O1—C2	1.2571 (17)	C10—C9	1.3955 (19)
C7—C12	1.3998 (17)	C10—H10	0.972 (17)
C7—C8	1.4054 (18)	C8—C9	1.3871 (18)
C7—C6	1.4687 (16)	C8—H8	0.951 (18)
C3—C4	1.3729 (17)	C1—H1B	0.97 (3)
C3—C2	1.4337 (16)	C1—H1C	0.94 (2)
C3—H3	0.949 (17)	C1—H1A	0.95 (3)
C12—C11	1.3931 (18)	C9—H9	1.002 (17)
C4—O2—H20	105.0 (14)	O1—C2—C1	118.96 (11)
C6—C5—C4	122.26 (12)	C3—C2—C1	120.02 (12)
C6—C5—H5	121.9 (9)	C10—C11—C12	120.22 (12)
C4—C5—H5	115.9 (9)	C10—C11—H11	121.7 (9)
C12—C7—C8	118.35 (11)	C12—C11—H11	118.1 (9)
C12—C7—C6	118.86 (11)	C11—C10—C9	119.55 (12)
C8—C7—C6	122.75 (11)	C11—C10—H10	119.7 (10)
C4—C3—C2	120.81 (12)	C9—C10—H10	120.7 (10)
C4—C3—H3	120.2 (10)	C9—C8—C7	120.52 (12)
C2—C3—H3	119.0 (10)	C9—C8—H8	118.4 (10)
C11—C12—C7	120.86 (12)	C7—C8—H8	121.0 (10)
C11—C12—H12	118.7 (10)	C2—C1—H1B	110.5 (15)
C7—C12—H12	120.5 (10)	C2—C1—H1C	116.3 (15)
C5—C6—C7	126.63 (12)	H1B—C1—H1C	111 (2)
C5—C6—H6	119.1 (9)	C2—C1—H1A	109.5 (17)
C7—C6—H6	114.2 (9)	H1B—C1—H1A	104 (2)
O2—C4—C3	121.16 (11)	H1C—C1—H1A	104 (2)
O2—C4—C5	116.09 (11)	C8—C9—C10	120.47 (12)
C3—C4—C5	122.74 (12)	C8—C9—H9	118.3 (9)
O1—C2—C3	121.02 (12)	C10—C9—H9	121.2 (9)
C8—C7—C12—C11	0.17 (19)	C4—C3—C2—O1	0.79 (19)
C6—C7—C12—C11	−177.86 (12)	C4—C3—C2—C1	−178.74 (11)
C4—C5—C6—C7	−175.97 (11)	C7—C12—C11—C10	1.2 (2)
C12—C7—C6—C5	−176.01 (12)	C12—C11—C10—C9	−1.4 (2)
C8—C7—C6—C5	6.1 (2)	C12—C7—C8—C9	−1.30 (18)
C2—C3—C4—O2	0.35 (19)	C6—C7—C8—C9	176.64 (11)
C2—C3—C4—C5	−178.34 (11)	C7—C8—C9—C10	1.07 (19)
C6—C5—C4—O2	3.09 (18)	C11—C10—C9—C8	0.3 (2)
C6—C5—C4—C3	−178.16 (12)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H20···O1	0.99 (3)	1.59 (3)	2.5085 (14)	152 (2)
C8—H8···O1^i	0.951 (18)	2.471 (18)	3.4159 (17)	172.0 (14)

Symmetry code: (i) x+1/2, −y+1/2, −z+2.