Second modification of (E)-2,3,2',3'-tetra­hydro-[1,1']­biindenyl­idene

A first crystalline modification of the title compound, C₁₈H₁₆, was published by Schaefer & Abul [Acta Cryst. (1995), C51, 2364-2366]. We now report on a second modification. Both modifications belong to the space group C2/c and, in both, the mol­ecules lie on centres of symmetry. In the first modification, the asymmetric unit contains one half mol­ecule, whereas in the second there are two half-mol­ecules in the asymmetric unit. The two crystallographically independent planar mol­ecules of the second modification are tilted by an angle of 63.4° with respect to one another.

Key indicators

• Single-crystal X-ray study
• T = 291 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.050
• wR factor = 0.097
• Data-to-parameter ratio = 17.3

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

---

S1. Comment

(E)-2,3,2',3'-Tetrahydro-[1,1']biindenylidene, (I), is one of four possible biindenylidene isomers, and the constituent of many pyrolysis oils. Its characterization is interesting for environmental analysis. It also represents a useful model substance for MS and NMR analysis, and structural data are important for the understanding of some fine details of MS and NMR spectra.

S2. Experimental

(E)-2,3,2',3'-Tetrahydro-[1,1']biindenylidene was synthesized through the reductive coupling of 1H-indan-1-one according to the method of Lenoir & Lemmen (1980). It was isolated by crystallization from propan-2-ol.

S3. Refinement

H atoms were placed in calculated positions with U_iso constrained to be 1.2 times U_eq of the carrier atom.

Computing details

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL-Plus (Sheldrick, 1991); software used to prepare material for publication: SHELXL97, PARST95 (Nardelli, 1995) and PLATON (Spek, 2001).

Figures

Fig. 1. View of the title compound (XP; Sheldrick, 1991) showing the labelling of all non-H atoms. The molecules are centrosymmetric. Displacement ellipsoids are shown at 50% probability levels. H atoms are drawn as circles of arbitrary radii.

(I)

Crystal data

C18H16	F(000) = 992
Mr = 232.31	Dx = 1.212 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 43.717 (5) Å	Cell parameters from 7904 reflections
b = 8.0751 (10) Å	θ = 3.5–27.5°
c = 7.2651 (12) Å	µ = 0.07 mm^−1
β = 96.860 (6)°	T = 291 K
V = 2546.4 (6) Å^3	Plate, light yellow
Z = 8	0.50 × 0.20 × 0.08 mm

Data collection

Nonius KappaCCD diffractometer	780 reflections with I > σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.024
Graphite monochromator	θmax = 27.5°, θmin = 3.5°
Detector resolution: 19 vertical, 18 horizontal pixels mm^-1	h = −55→55
588 frames via ω–rotation (Δω=0.5%) and two times 20 s perframe (three sets at different κ–angles) scans	k = −10→10
2826 measured reflections	l = −9→9
2826 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)] = 0.050	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.097	H-atom parameters constrained
S = 0.83	w = 1/[σ^2(Fo^2) + (0.015P)^2] where P = (Fo^2 + 2Fc^2)/3
2826 reflections	(Δ/σ)max < 0.001
163 parameters	Δρmax = 0.15 e Å^−3
0 restraints	Δρmin = −0.14 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
C11	0.01521 (4)	1.0118 (3)	0.0133 (3)	0.0502 (8)
C12	0.03039 (5)	1.1832 (3)	0.0262 (3)	0.0583 (7)
H12A	0.0241	1.2451	0.1297	0.070*
H12B	0.0247	1.2455	−0.0869	0.070*
C13	0.06565 (5)	1.1502 (3)	0.0552 (3)	0.0652 (8)
H13A	0.0755	1.1982	−0.0450	0.078*
H13B	0.0749	1.1972	0.1716	0.078*
C14	0.06890 (7)	0.9662 (4)	0.0569 (3)	0.0543 (7)
C15	0.09603 (6)	0.8768 (4)	0.0803 (3)	0.0659 (8)
H15	0.1149	0.9315	0.0975	0.079*
C16	0.09508 (7)	0.7075 (4)	0.0783 (3)	0.0729 (9)
H16	0.1133	0.6469	0.0920	0.087*
C17	0.06692 (8)	0.6265 (3)	0.0558 (3)	0.0747 (9)
H17	0.0663	0.5114	0.0562	0.090*
C18	0.03965 (6)	0.7159 (4)	0.0327 (3)	0.0647 (8)
H18	0.0209	0.6602	0.0170	0.078*
C19	0.04016 (6)	0.8894 (4)	0.0329 (3)	0.0523 (7)
C21	0.23499 (4)	0.7659 (3)	0.4731 (3)	0.0479 (7)
C22	0.22266 (5)	0.8502 (3)	0.2909 (3)	0.0660 (8)
H22A	0.2276	0.7850	0.1862	0.079*
H22B	0.2317	0.9594	0.2835	0.079*
C23	0.18768 (5)	0.8634 (3)	0.2900 (3)	0.0747 (9)
H23A	0.1812	0.9784	0.2867	0.090*
H23B	0.1770	0.8065	0.1834	0.090*
C24	0.18113 (6)	0.7826 (3)	0.4661 (3)	0.0554 (7)
C25	0.15281 (6)	0.7589 (3)	0.5273 (4)	0.0646 (8)
H25	0.1350	0.7944	0.4554	0.077*
C26	0.15098 (6)	0.6829 (3)	0.6943 (4)	0.0696 (9)
H26	0.1319	0.6672	0.7363	0.084*
C27	0.17765 (7)	0.6294 (3)	0.8006 (4)	0.0693 (8)
H27	0.1763	0.5782	0.9140	0.083*
C28	0.20603 (6)	0.6511 (3)	0.7400 (4)	0.0654 (8)
H28	0.2237	0.6147	0.8123	0.078*
C29	0.20818 (5)	0.7280 (3)	0.5700 (4)	0.0503 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C11	0.0607 (17)	0.049 (2)	0.0410 (16)	−0.001 (2)	0.0078 (17)	0.0024 (13)
C12	0.0649 (17)	0.055 (2)	0.0553 (18)	−0.0024 (16)	0.0080 (13)	−0.0018 (14)
C13	0.0549 (18)	0.076 (3)	0.0639 (18)	−0.0048 (17)	0.0035 (13)	0.0008 (18)
C14	0.064 (2)	0.047 (2)	0.0511 (18)	0.001 (2)	0.0033 (14)	0.0048 (16)
C15	0.058 (2)	0.066 (3)	0.072 (2)	0.004 (2)	0.0035 (14)	0.0076 (19)
C16	0.070 (2)	0.072 (3)	0.077 (2)	0.016 (2)	0.0081 (16)	0.007 (2)
C17	0.081 (2)	0.064 (2)	0.079 (2)	0.009 (2)	0.0098 (18)	0.0040 (18)
C18	0.064 (2)	0.060 (3)	0.0684 (19)	0.0015 (19)	0.0018 (14)	−0.0026 (18)
C19	0.058 (2)	0.051 (2)	0.0471 (17)	−0.0016 (19)	0.0044 (13)	0.0029 (16)
C21	0.0511 (15)	0.0443 (19)	0.0471 (16)	0.0024 (16)	0.0012 (16)	0.0030 (13)
C22	0.0564 (17)	0.079 (2)	0.0616 (18)	0.0040 (15)	0.0014 (13)	0.0128 (17)
C23	0.0586 (18)	0.097 (3)	0.067 (2)	0.0119 (16)	0.0029 (15)	0.0120 (18)
C24	0.0479 (17)	0.063 (2)	0.0550 (18)	−0.0011 (16)	0.0049 (15)	−0.0026 (16)
C25	0.056 (2)	0.069 (2)	0.068 (2)	0.0046 (15)	0.0035 (16)	−0.0064 (18)
C26	0.064 (2)	0.066 (2)	0.082 (2)	−0.0056 (17)	0.0215 (18)	−0.0120 (19)
C27	0.072 (2)	0.064 (2)	0.072 (2)	0.0015 (18)	0.0101 (19)	0.0111 (16)
C28	0.0554 (19)	0.072 (2)	0.069 (2)	0.0015 (16)	0.0087 (15)	0.0071 (18)
C29	0.0506 (17)	0.047 (2)	0.0529 (18)	0.0009 (15)	0.0026 (16)	−0.0027 (15)

Geometric parameters (Å, º)

C11—C11^i	1.335 (4)	C21—C21^ii	1.349 (4)
C11—C19	1.466 (3)	C21—C29	1.470 (3)
C11—C12	1.532 (3)	C21—C22	1.528 (3)
C12—C13	1.553 (3)	C22—C23	1.532 (2)
C12—H12A	0.9700	C22—H22A	0.9700
C12—H12B	0.9700	C22—H22B	0.9700
C13—C14	1.492 (3)	C23—C24	1.494 (3)
C13—H13A	0.9700	C23—H23A	0.9700
C13—H13B	0.9700	C23—H23B	0.9700
C14—C15	1.382 (3)	C24—C25	1.378 (3)
C14—C19	1.394 (3)	C24—C29	1.396 (3)
C15—C16	1.368 (3)	C25—C26	1.371 (3)
C15—H15	0.9300	C25—H25	0.9300
C16—C17	1.386 (3)	C26—C27	1.389 (3)
C16—H16	0.9300	C26—H26	0.9300
C17—C18	1.386 (3)	C27—C28	1.376 (3)
C17—H17	0.9300	C27—H27	0.9300
C18—C19	1.401 (3)	C28—C29	1.396 (3)
C18—H18	0.9300	C28—H28	0.9300
C11^i—C11—C19	129.3 (3)	C21^ii—C21—C29	128.7 (3)
C11^i—C11—C12	123.7 (3)	C21^ii—C21—C22	124.5 (3)
C19—C11—C12	106.94 (19)	C29—C21—C22	106.78 (18)
C11—C12—C13	105.60 (19)	C21—C22—C23	106.46 (17)
C11—C12—H12A	110.6	C21—C22—H22A	110.4
C13—C12—H12A	110.6	C23—C22—H22A	110.4
C11—C12—H12B	110.6	C21—C22—H22B	110.4
C13—C12—H12B	110.6	C23—C22—H22B	110.4
H12A—C12—H12B	108.8	H22A—C22—H22B	108.6
C14—C13—C12	105.3 (2)	C24—C23—C22	105.02 (18)
C14—C13—H13A	110.7	C24—C23—H23A	110.7
C12—C13—H13A	110.7	C22—C23—H23A	110.7
C14—C13—H13B	110.7	C24—C23—H23B	110.7
C12—C13—H13B	110.7	C22—C23—H23B	110.7
H13A—C13—H13B	108.8	H23A—C23—H23B	108.8
C15—C14—C19	122.0 (3)	C25—C24—C29	121.2 (2)
C15—C14—C13	126.9 (3)	C25—C24—C23	127.5 (2)
C19—C14—C13	111.0 (3)	C29—C24—C23	111.4 (2)
C16—C15—C14	119.8 (3)	C26—C25—C24	119.8 (2)
C16—C15—H15	120.1	C26—C25—H25	120.1
C14—C15—H15	120.1	C24—C25—H25	120.1
C15—C16—C17	119.9 (3)	C25—C26—C27	119.8 (2)
C15—C16—H16	120.0	C25—C26—H26	120.1
C17—C16—H16	120.0	C27—C26—H26	120.1
C16—C17—C18	120.5 (3)	C28—C27—C26	120.8 (2)
C16—C17—H17	119.8	C28—C27—H27	119.6
C18—C17—H17	119.8	C26—C27—H27	119.6
C17—C18—C19	120.5 (2)	C27—C28—C29	119.9 (2)
C17—C18—H18	119.8	C27—C28—H28	120.1
C19—C18—H18	119.8	C29—C28—H28	120.1
C14—C19—C18	117.3 (2)	C28—C29—C24	118.5 (2)
C14—C19—C11	111.1 (3)	C28—C29—C21	131.2 (2)
C18—C19—C11	131.5 (3)	C24—C29—C21	110.3 (2)
C11^i—C11—C12—C13	−179.5 (3)	C21^ii—C21—C22—C23	−179.0 (3)
C19—C11—C12—C13	−0.2 (2)	C29—C21—C22—C23	1.6 (2)
C11—C12—C13—C14	0.1 (2)	C21—C22—C23—C24	−1.7 (2)
C12—C13—C14—C15	−179.4 (2)	C22—C23—C24—C25	−178.1 (2)
C12—C13—C14—C19	−0.1 (3)	C22—C23—C24—C29	1.3 (3)
C19—C14—C15—C16	0.7 (4)	C29—C24—C25—C26	1.1 (4)
C13—C14—C15—C16	−179.9 (2)	C23—C24—C25—C26	−179.5 (3)
C14—C15—C16—C17	−1.1 (4)	C24—C25—C26—C27	−0.4 (4)
C15—C16—C17—C18	0.9 (4)	C25—C26—C27—C28	−0.2 (4)
C16—C17—C18—C19	−0.4 (4)	C26—C27—C28—C29	0.1 (4)
C15—C14—C19—C18	−0.2 (4)	C27—C28—C29—C24	0.7 (3)
C13—C14—C19—C18	−179.6 (2)	C27—C28—C29—C21	−179.8 (2)
C15—C14—C19—C11	179.3 (2)	C25—C24—C29—C28	−1.3 (3)
C13—C14—C19—C11	−0.1 (3)	C23—C24—C29—C28	179.3 (2)
C17—C18—C19—C14	0.0 (4)	C25—C24—C29—C21	179.1 (2)
C17—C18—C19—C11	−179.4 (2)	C23—C24—C29—C21	−0.4 (3)
C11^i—C11—C19—C14	179.4 (3)	C21^ii—C21—C29—C28	0.2 (5)
C12—C11—C19—C14	0.2 (3)	C22—C21—C29—C28	179.6 (2)
C11^i—C11—C19—C18	−1.1 (5)	C21^ii—C21—C29—C24	179.8 (3)
C12—C11—C19—C18	179.6 (2)	C22—C21—C29—C24	−0.8 (2)

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