1,2-Bis{2-[2-(trimethyl­sil­yl)ethyn­yl]phen­yl}ethane-1,2-dione

The title compound, C₂₄H₂₆O₂Si₂, has C₂ crystallographic symmetry. The dihedral angle between the aromatic rings is 84.5 (2)°. The acetyl­ene group is slightly non-linear, with angles at the acetyl­ene C atoms of 175.7 (2) and 177.0 (2)°. In the crystal structure, only van de Waals interactions occur.

Key indicators

• Single-crystal X-ray study
• T = 120 K, P = 0.0 kPa
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.043
• wR factor = 0.103
• Data-to-parameter ratio = 26.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT230_ALERT_2_C Hirshfeld Test Diff for    Si1    --  C4      ..        5.4 su
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        Si1
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C12    -   C12_a  ...       1.54 Ang.
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          2

Alert level G
REFLT03_ALERT_1_G ALERT: Expected hkl max differ from CIF values
           From the CIF: _diffrn_reflns_theta_max           30.03
           From the CIF: _reflns_number_total               3410
           From the CIF: _diffrn_reflns_limit_ max hkl   12.   10.   33.
           From the CIF: _diffrn_reflns_limit_ min hkl  -12.  -10.  -31.
           TEST1: Expected hkl limits for theta max
           Calculated maximum hkl   12.   12.   33.
           Calculated minimum hkl  -12.  -12.  -33.
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           30.03
           From the CIF: _reflns_number_total               3410
           Count of symmetry unique reflns         1993
           Completeness (_total/calc)            171.10%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured      1417
           Fraction of Friedel pairs measured     0.711
           Are heavy atom types Z>Si present        yes
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT371_ALERT_2_G Long   C(sp2)-C(sp1) Bond  C5     -   C6     ...       1.44 Ang.
PLAT850_ALERT_4_G Check Flack Parameter Exact Value 0.00 and su ..       0.10
PLAT951_ALERT_5_G Reported and Calculated Kmax Values Differ by ..          2

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   4 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   6 ALERT level G = General information/check it is not something unexpected

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   4 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   2 ALERT type 5 Informative message, check

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S1. Comment

The title compound (I), (C₁₂H₁₃OSi)₂, lies on a crystallographic twofold axis. The phenyl ring is planar - all six C atoms have δ/σ < 0.2. However, carbonyl carbon C12 is 0.217 (5) Å above the C11—O1—C12' plane, and the C10—C11—C12—O1 torsion angle is 19.5 (3)°. The ethanedione C12(sp²)—C12(sp²)' distance of 1.538 (4) Å is somewhat longer than expected, but is consistent with values reported for benzil, which average 1.536 (10) Å. The acetylenic moiety is non-linear with deviations from a weighted least-squares line of δ(Si1) = 0.0034 (15), δ(C4) = 0.054 (4), δ(C5) = 0.049 (4), and δ(C6) = 0.047 (4) Å. The crystal structure is stablized by van der Waals interactions.

Related literature

For the structure of benzil, see Brown & Sadanaga (1965); Gabe et al. (1981); More et al. (1987). For the synthesis see: Garcia et al. (1995). For the determination of absolute configuration from Bijvoet pairs, see: Hooft et al. (2008).

S2. Experimental

The title compound was supplied by J. Gabriel Garcia, having been synthesized from 1,2-bis-(2-bromophenyl)-ethane-1,2-dione and trimethylsilyl acetylene (Garcia et al., 1995).

S3. Refinement

The space group assignment and absolute structure are based on analysis of 1419 Bijvoet pairs, Flack (1983) parameter x = 0.0 (1), Hooft et al. (2008) parameter y = -0.04 (7), and Hooft P2(true) = 1.000.

All H atoms were placed in calculated positions with C—H distances of 0.95 (aromatic) and 0.98 Å (methyl) and U_iso = 1.2 or 1.5 U_eq of the attached sp² or sp³ C atom, and thereafter treated as riding. A torsional parameter was refined for each methyl group.

Computing details

Data collection: COLLECT (Nonius, 2000); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR2002 (Burla et al., 2003); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

Figure 1. View of (I) (50% probability displacement ellipsoids)

1,2-Bis{2-[2-(trimethylsilyl)ethynyl]phenyl}ethane-1,2-dione

Crystal data

C24H26O2Si2	Dx = 1.145 Mg m^−3
Mr = 402.63	Mo Kα radiation, λ = 0.71073 Å
Trigonal, P3221	Cell parameters from 3424 reflections
Hall symbol: P 32 2"	θ = 2.5–30.0°
a = 9.2241 (1) Å	µ = 0.17 mm^−1
c = 23.7787 (5) Å	T = 120 K
V = 1752.13 (5) Å^3	Rhombohedron, yellow
Z = 3	0.25 × 0.25 × 0.25 mm
F(000) = 642

Data collection

Nonius KappaCCD diffractometer	3410 independent reflections
Radiation source: sealed tube	2325 reflections with I > 2σ(I)
Horizonally mounted graphite crystal monochromator	Rint = 0.047
Detector resolution: 9 pixels mm^-1	θmax = 30.0°, θmin = 2.6°
ω and ϕ scans	h = −12→12
Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor, 1997)	k = −10→10
Tmin = 0.959, Tmax = 0.959	l = −31→33
23012 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.043	H-atom parameters constrained
wR(F^2) = 0.103	w = 1/[σ^2(Fo^2) + (0.0519P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.00	(Δ/σ)max < 0.001
3410 reflections	Δρmax = 0.25 e Å^−3
131 parameters	Δρmin = −0.21 e Å^−3
0 restraints	Absolute structure: Flack (1983), 1419 Bijvoet pairs
0 constraints	Absolute structure parameter: 0.0 (1)
Primary atom site location: structure-invariant direct methods

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C1	0.4411 (3)	−0.1681 (3)	0.00979 (9)	0.0487 (6)
H1A	0.5479	−0.0985	−0.0095	0.073*
H1B	0.3539	−0.233	−0.018	0.073*
H1C	0.4522	−0.2447	0.0357	0.073*
C2	0.1985 (3)	−0.1571 (4)	0.09491 (10)	0.0714 (8)
H2A	0.2222	−0.2247	0.1211	0.107*
H2B	0.1022	−0.2309	0.0714	0.107*
H2C	0.1731	−0.0815	0.1162	0.107*
C3	0.3475 (4)	0.1018 (3)	0.00053 (11)	0.0802 (10)
H3A	0.3209	0.1763	0.0219	0.12*
H3B	0.2539	0.0314	−0.0245	0.12*
H3C	0.4487	0.1688	−0.0219	0.12*
C4	0.5616 (2)	0.1008 (2)	0.09647 (7)	0.0310 (4)
C5	0.6750 (2)	0.1814 (2)	0.12846 (7)	0.0282 (4)
C6	0.8026 (2)	0.2815 (2)	0.16901 (6)	0.0283 (4)
C7	0.8414 (2)	0.4474 (2)	0.17783 (8)	0.0346 (5)
H7	0.7881	0.4931	0.1558	0.042*
C8	0.9559 (2)	0.5446 (2)	0.21811 (8)	0.0385 (5)
H8	0.982	0.6572	0.2233	0.046*
C9	1.0332 (2)	0.4800 (2)	0.25096 (7)	0.0381 (5)
H9	1.1116	0.5479	0.2789	0.046*
C10	0.9970 (2)	0.3169 (2)	0.24337 (7)	0.0352 (4)
H10	1.0497	0.2725	0.2664	0.042*
C11	0.8830 (2)	0.2166 (2)	0.20188 (7)	0.0274 (4)
C12	0.8518 (2)	0.0429 (2)	0.19563 (7)	0.0309 (4)
O1	0.88376 (18)	−0.02847 (17)	0.23231 (6)	0.0457 (4)
Si1	0.38331 (7)	−0.03278 (7)	0.04974 (2)	0.03309 (15)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0621 (15)	0.0523 (14)	0.0410 (11)	0.0355 (13)	−0.0166 (11)	−0.0167 (10)
C2	0.0331 (13)	0.092 (2)	0.0657 (15)	0.0134 (14)	−0.0059 (12)	−0.0155 (14)
C3	0.108 (2)	0.0446 (14)	0.0940 (18)	0.0423 (15)	−0.0758 (18)	−0.0214 (13)
C4	0.0351 (10)	0.0292 (10)	0.0311 (9)	0.0178 (9)	−0.0057 (8)	−0.0005 (8)
C5	0.0316 (10)	0.0258 (9)	0.0288 (9)	0.0156 (8)	−0.0008 (8)	0.0041 (8)
C6	0.0246 (9)	0.0290 (10)	0.0243 (8)	0.0083 (8)	0.0013 (7)	0.0042 (8)
C7	0.0346 (11)	0.0295 (11)	0.0344 (10)	0.0120 (9)	−0.0044 (8)	0.0022 (8)
C8	0.0361 (12)	0.0273 (11)	0.0401 (11)	0.0068 (10)	0.0020 (9)	−0.0008 (8)
C9	0.0256 (10)	0.0386 (11)	0.0312 (9)	0.0019 (9)	−0.0042 (8)	−0.0033 (8)
C10	0.0233 (9)	0.0403 (11)	0.0339 (9)	0.0098 (9)	−0.0013 (8)	0.0075 (8)
C11	0.0194 (8)	0.0302 (9)	0.0260 (8)	0.0075 (8)	0.0033 (7)	0.0069 (7)
C12	0.0196 (9)	0.0329 (10)	0.0361 (10)	0.0101 (8)	0.0025 (8)	0.0105 (8)
O1	0.0440 (9)	0.0402 (9)	0.0499 (8)	0.0188 (8)	−0.0108 (7)	0.0125 (7)
Si1	0.0354 (3)	0.0283 (3)	0.0372 (3)	0.0172 (3)	−0.0128 (2)	−0.0072 (2)

Geometric parameters (Å, º)

C1—Si1	1.847 (2)	C5—C6	1.443 (2)
C1—H1A	0.98	C6—C7	1.403 (3)
C1—H1B	0.98	C6—C11	1.401 (3)
C1—H1C	0.98	C7—C8	1.375 (3)
C2—Si1	1.849 (2)	C7—H7	0.95
C2—H2A	0.98	C8—C9	1.378 (3)
C2—H2B	0.98	C8—H8	0.95
C2—H2C	0.98	C9—C10	1.380 (3)
C3—Si1	1.852 (2)	C9—H9	0.95
C3—H3A	0.98	C10—C11	1.401 (2)
C3—H3B	0.98	C10—H10	0.95
C3—H3C	0.98	C11—C12	1.487 (3)
C4—C5	1.203 (2)	C12—O1	1.214 (2)
C4—Si1	1.8522 (19)	C12—C12^i	1.538 (4)
Si1—C1—H1A	109.5	C8—C7—H7	119.7
Si1—C1—H1B	109.5	C6—C7—H7	119.7
H1A—C1—H1B	109.5	C9—C8—C7	120.52 (19)
Si1—C1—H1C	109.5	C9—C8—H8	119.7
H1A—C1—H1C	109.5	C7—C8—H8	119.7
H1B—C1—H1C	109.5	C8—C9—C10	120.12 (17)
Si1—C2—H2A	109.5	C8—C9—H9	119.9
Si1—C2—H2B	109.5	C10—C9—H9	119.9
H2A—C2—H2B	109.5	C9—C10—C11	120.31 (17)
Si1—C2—H2C	109.5	C9—C10—H10	119.8
H2A—C2—H2C	109.5	C11—C10—H10	119.8
H2B—C2—H2C	109.5	C6—C11—C10	119.58 (17)
Si1—C3—H3A	109.5	C6—C11—C12	123.09 (16)
Si1—C3—H3B	109.5	C10—C11—C12	117.32 (17)
H3A—C3—H3B	109.5	O1—C12—C11	122.93 (17)
Si1—C3—H3C	109.5	O1—C12—C12^i	115.72 (18)
H3A—C3—H3C	109.5	C11—C12—C12^i	120.33 (17)
H3B—C3—H3C	109.5	C3—Si1—C1	109.67 (11)
C5—C4—Si1	177.01 (16)	C3—Si1—C2	111.37 (14)
C4—C5—C6	175.7 (2)	C1—Si1—C2	111.58 (13)
C7—C6—C11	118.82 (16)	C3—Si1—C4	109.27 (10)
C7—C6—C5	118.66 (17)	C1—Si1—C4	107.33 (9)
C11—C6—C5	122.44 (17)	C2—Si1—C4	107.49 (9)
C8—C7—C6	120.63 (18)
C11—C6—C7—C8	−0.2 (3)	C9—C10—C11—C6	−1.6 (3)
C5—C6—C7—C8	176.61 (16)	C9—C10—C11—C12	179.24 (16)
C6—C7—C8—C9	−0.7 (3)	C6—C11—C12—O1	−159.64 (18)
C7—C8—C9—C10	0.5 (3)	C10—C11—C12—O1	19.5 (3)
C8—C9—C10—C11	0.7 (3)	C6—C11—C12—C12^i	32.4 (2)
C7—C6—C11—C10	1.3 (2)	C10—C11—C12—C12^i	−148.44 (13)
C5—C6—C11—C10	−175.35 (16)	C11—C12—C12^i—C11^i	−132.9 (2)
C7—C6—C11—C12	−179.56 (16)	C11—C12—C12^i—O1^i	58.36 (11)
C5—C6—C11—C12	3.8 (3)	O1—C12—C12^i—O1^i	−110.4 (3)

Symmetry code: (i) x−y, −y, −z+1/3.