Dimethyl 4,4′-(di­methyl­silanedi­yl)dibenzoate

The complete mol­ecule of the title compound, C₁₈H₂₀O₄Si, is generated by crystallographic twofold symmetry, with the Si atom lying on the rotation axis. The mol­ecule adopts a V-shape: the dihedral angle between the benzene ring and it attached methyl formate unit is 9.3 (2)°, and the dihedral angle between the benzene rings is 68.8 (1)°. In the crystal, weak C—H...O hydrogen bonds link the mol­ecules into [101] chains.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.044
• wR factor = 0.130
• Data-to-parameter ratio = 18.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT480_ALERT_4_C Long H...A H-Bond Reported H1A    ..  O2      ..       2.62 Ang.
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          1 Note
              C18 H20 O4 Si

Alert level G
PLAT005_ALERT_5_G No Embedded Refinement Details found  in the CIF     Please Do !
PLAT066_ALERT_1_G Predicted and Reported Tmin&Tmax Range Identical          ? Check
PLAT128_ALERT_4_G Alternate Setting for Input Space Group     C2/c       I2/a Note
PLAT152_ALERT_1_G The Supplied and Calc. Volume s.u. Differ by ...          2 Units
PLAT899_ALERT_4_G SHELXL97   is Deprecated and Succeeded by SHELXL       2014 Note
PLAT910_ALERT_3_G Missing # of FCF Reflection(s) Below Theta(Min)           3 Note
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600          6 Note
PLAT978_ALERT_2_G Number C-C Bonds with Positive Residual Density           6 Note

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

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 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
   5 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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Computing details

Data collection: RAPID-AUTO (Rigaku, 1998); cell refinement: RAPID-AUTO (Rigaku, 1998); data reduction: CrystalStructure (Rigaku/MSC and Rigaku, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Dimethyl 4,4'-(dimethylsilanediyl)dibenzoate

Crystal data

C18H20O4Si	F(000) = 696
Mr = 328.43	Dx = 1.262 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 7030 reflections
a = 15.869 (3) Å	θ = 3.5–27.5°
b = 9.991 (2) Å	µ = 0.15 mm^−1
c = 12.328 (3) Å	T = 296 K
β = 117.79 (3)°	Block, colorless
V = 1729.1 (6) Å^3	0.36 × 0.35 × 0.18 mm
Z = 4

Data collection

Rigaku R-AXIS RAPID CCD diffractometer	1974 independent reflections
Radiation source: fine-focus sealed tube	1647 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
ω scans	θmax = 27.5°, θmin = 3.5°
Absorption correction: multi-scan (RAPID-AUTO; Rigaku, 1998)	h = −20→17
Tmin = 0.948, Tmax = 0.974	k = −12→12
8251 measured reflections	l = −15→16

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.130	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0867P)^2 + 0.2156P] where P = (Fo^2 + 2Fc^2)/3
1974 reflections	(Δ/σ)max = 0.010
107 parameters	Δρmax = 0.34 e Å^−3
0 restraints	Δρmin = −0.15 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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
C1	0.54323 (13)	0.86561 (16)	1.16029 (15)	0.0529 (4)
H1A	0.4953	0.9300	1.1125	0.079*
H1B	0.5560	0.8090	1.1068	0.079*
H1C	0.6005	0.9113	1.2155	0.079*
C2	0.40084 (10)	0.64788 (13)	1.14363 (12)	0.0378 (3)
C3	0.41296 (11)	0.56740 (17)	1.05964 (16)	0.0522 (4)
H3	0.4702	0.5715	1.0562	0.063*
C4	0.34246 (11)	0.48152 (17)	0.98120 (15)	0.0513 (4)
H4	0.3521	0.4303	0.9249	0.062*
C5	0.25723 (9)	0.47202 (14)	0.98686 (13)	0.0400 (3)
C6	0.24381 (11)	0.54968 (16)	1.07046 (15)	0.0487 (4)
H6	0.1871	0.5434	1.0752	0.058*
C7	0.31455 (11)	0.63684 (16)	1.14723 (14)	0.0470 (4)
H7	0.3042	0.6891	1.2023	0.056*
C8	0.17949 (10)	0.37917 (15)	0.90651 (13)	0.0437 (4)
C9	0.12150 (13)	0.23692 (19)	0.73424 (17)	0.0623 (5)
H9A	0.1119	0.1643	0.7783	0.094*
H9B	0.1401	0.2020	0.6761	0.094*
H9C	0.0633	0.2866	0.6918	0.094*
O1	0.19538 (8)	0.32396 (12)	0.81941 (11)	0.0559 (3)
O2	0.10978 (9)	0.35693 (14)	0.91819 (12)	0.0667 (4)
Si1	0.5000	0.76151 (5)	1.2500	0.0378 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0619 (10)	0.0484 (8)	0.0529 (9)	−0.0023 (7)	0.0306 (8)	0.0075 (7)
C2	0.0385 (7)	0.0404 (7)	0.0336 (6)	0.0032 (5)	0.0160 (5)	0.0029 (5)
C3	0.0419 (8)	0.0650 (10)	0.0570 (9)	−0.0078 (7)	0.0292 (7)	−0.0168 (7)
C4	0.0490 (8)	0.0608 (9)	0.0518 (9)	−0.0065 (7)	0.0301 (7)	−0.0167 (7)
C5	0.0361 (7)	0.0427 (7)	0.0376 (7)	0.0020 (5)	0.0140 (5)	0.0029 (5)
C6	0.0376 (7)	0.0605 (9)	0.0518 (9)	−0.0015 (6)	0.0241 (7)	−0.0045 (7)
C7	0.0466 (8)	0.0536 (8)	0.0454 (8)	0.0013 (6)	0.0253 (7)	−0.0074 (6)
C8	0.0385 (7)	0.0453 (8)	0.0424 (8)	0.0021 (5)	0.0148 (6)	0.0022 (6)
C9	0.0545 (10)	0.0659 (11)	0.0546 (10)	−0.0100 (8)	0.0153 (8)	−0.0173 (8)
O1	0.0473 (6)	0.0658 (7)	0.0525 (7)	−0.0100 (5)	0.0215 (5)	−0.0177 (5)
O2	0.0516 (7)	0.0819 (9)	0.0720 (9)	−0.0195 (6)	0.0333 (6)	−0.0199 (7)
Si1	0.0413 (3)	0.0377 (3)	0.0356 (3)	0.000	0.0188 (2)	0.000

Geometric parameters (Å, º)

C1—Si1	1.8662 (16)	C5—C8	1.491 (2)
C1—H1A	0.9600	C6—C7	1.387 (2)
C1—H1B	0.9600	C6—H6	0.9300
C1—H1C	0.9600	C7—H7	0.9300
C2—C3	1.393 (2)	C8—O2	1.2009 (19)
C2—C7	1.395 (2)	C8—O1	1.3318 (19)
C2—Si1	1.8869 (15)	C9—O1	1.4440 (19)
C3—C4	1.383 (2)	C9—H9A	0.9600
C3—H3	0.9300	C9—H9B	0.9600
C4—C5	1.390 (2)	C9—H9C	0.9600
C4—H4	0.9300	Si1—C1^i	1.8662 (16)
C5—C6	1.383 (2)	Si1—C2^i	1.8869 (15)
Si1—C1—H1A	109.5	C7—C6—H6	119.9
Si1—C1—H1B	109.5	C6—C7—C2	121.47 (14)
H1A—C1—H1B	109.5	C6—C7—H7	119.3
Si1—C1—H1C	109.5	C2—C7—H7	119.3
H1A—C1—H1C	109.5	O2—C8—O1	123.46 (14)
H1B—C1—H1C	109.5	O2—C8—C5	123.95 (14)
C3—C2—C7	117.11 (13)	O1—C8—C5	112.59 (13)
C3—C2—Si1	120.29 (11)	O1—C9—H9A	109.5
C7—C2—Si1	122.57 (11)	O1—C9—H9B	109.5
C4—C3—C2	122.03 (14)	H9A—C9—H9B	109.5
C4—C3—H3	119.0	O1—C9—H9C	109.5
C2—C3—H3	119.0	H9A—C9—H9C	109.5
C3—C4—C5	119.74 (14)	H9B—C9—H9C	109.5
C3—C4—H4	120.1	C8—O1—C9	116.16 (13)
C5—C4—H4	120.1	C1^i—Si1—C1	112.26 (11)
C6—C5—C4	119.38 (14)	C1^i—Si1—C2	109.23 (7)
C6—C5—C8	118.47 (13)	C1—Si1—C2	109.96 (7)
C4—C5—C8	122.15 (14)	C1^i—Si1—C2^i	109.96 (7)
C5—C6—C7	120.25 (14)	C1—Si1—C2^i	109.23 (7)
C5—C6—H6	119.9	C2—Si1—C2^i	106.02 (9)
C7—C2—C3—C4	1.1 (2)	C4—C5—C8—O2	171.12 (16)
Si1—C2—C3—C4	179.15 (13)	C6—C5—C8—O1	171.45 (13)
C2—C3—C4—C5	−1.3 (3)	C4—C5—C8—O1	−9.3 (2)
C3—C4—C5—C6	0.5 (2)	O2—C8—O1—C9	2.1 (2)
C3—C4—C5—C8	−178.70 (15)	C5—C8—O1—C9	−177.48 (13)
C4—C5—C6—C7	0.5 (2)	C3—C2—Si1—C1^i	174.94 (12)
C8—C5—C6—C7	179.71 (14)	C7—C2—Si1—C1^i	−7.11 (14)
C5—C6—C7—C2	−0.7 (2)	C3—C2—Si1—C1	51.33 (14)
C3—C2—C7—C6	−0.1 (2)	C7—C2—Si1—C1	−130.71 (13)
Si1—C2—C7—C6	−178.09 (12)	C3—C2—Si1—C2^i	−66.63 (12)
C6—C5—C8—O2	−8.1 (2)	C7—C2—Si1—C2^i	111.33 (13)

Symmetry code: (i) −x+1, y, −z+5/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1A···O2^ii	0.96	2.62	3.511 (2)	154
C9—H9C···O2^iii	0.96	2.53	3.465 (3)	164

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