Tris(4-meth­oxy­phen­yl)stibine

Böhm, M.J.; Golz, C.; Alcarazo, M.

doi:10.1107/S2414314618009896

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 3| Part 7| July 2018| x180989

https://doi.org/10.1107/S2414314618009896

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Tris(4-methoxyphenyl)stibine

Marvin J. Böhm,^a Christopher Golz ^a and Manuel Alcarazo ^a ^*

^aGeorg-August-Universität Göttingen, Institut für Organische und Biomolekulare Chemie, Tammannstrasse 2, D-37077 Göttingen, Germany
^*Correspondence e-mail: malcara@gwdg.de

Edited by J. Simpson, University of Otago, New Zealand (Received 21 June 2018; accepted 10 July 2018; online 20 July 2018)

The C₃-symmetrical molecule, tris(4-methoxyphenyl)stibine, C₂₁H₂₁O₃Sb, crystallizes with one third of the molecule in the asymmetric unit. Bond lengths and angles of the Sb—C bonds lie in between those of the isostructural homologues C₂₁H₂₁O₃Bi and C₂₁H₂₁O₃As. The formation of dimers via six weak C—H⋯π interactions is considered.

Keywords: crystal structure; antimony; methylanisole.

CCDC reference: 1854911

Structure description

The title compound, C₂₁H₂₁O₃Sb, exhibits perfect C₃-symmetry with one third of the molecule in the asymmetric unit. To our surprise, the structure of the title compound (Fig. 1) is not reported in the database (CSD; Groom et al., 2016 ), although we regularly observe it as a side product in our synthesis of asymmetric sulfides (Böhm et al., 2018 ). To fill the gap in the row of homologues of the type C₂₁H₂₁O₃E, with E being an element of group 14, the title compound is reported herein. It is isostructural with the homologues C₂₁H₂₁O₃Bi (Hébert et al., 2016 ) and C₂₁H₂₁O₃As (Sobolev & Belsky, 1981 ). The lighter homologue C₂₁H₂₁O₃P (Allman et al., 1986 ; Bruckmann et al., 1995 ) crystallizes in the space group P2₁/c while the lightest homologue C₂₁H₂₁O₃N is, so far, not known in the CSD. The Sb—C bond distance and C—Sb—C angle observed here, 2.148 (2) Å and 95.8 (1)°, lie between those of the neighbouring isostructural As and Bi homologues. However, the Sb—C bond distance is closer to that of the Bi derivative with the Bi—C distances being 0.103 Å longer, and the As—C distance 0.175 Å shorter, than that observed for the title compound. No strong intermolecular interactions were observed, Fig. 2. The distances between the C1–C6 centroid and atoms C5 or C3 of the next molecules [3.814 (2) and 3.849 (2) Å, respectively] indicate weak C—H⋯π interactions, Table 1 and Fig. 3. It is noteworthy that two molecules are connected by six of these weak C—H⋯π interactions via C3, forming discrete dimeric units with the antimony atom facing outwards.

Table 1
C—H⋯π interactions (Å, °)

Cg1 is the centroid of the C1–C6 benzene ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3⋯Cg1ⁱ	0.93	3.11	3.849 (2)	138
C5—H5⋯Cg1ⁱⁱ	0.93	2.91	3.814 (2)	165
Symmetry codes: (i) $[-x+y+{\script{2\over 3}}, -x+{\script{1\over 3}}, z+{\script{4\over 3}}]$ ; (ii) $[x-y+{\script{1\over 3}}, x+{\script{2\over 3}}, -z+{\script{5\over 3}}]$ .

Figure 1
Displacement ellipsoid plot (50% probability) of the title compound. Symmetry codes used to generate the complete molecule: (i) y – x, 1 − x, z; (ii) 1 − y, 1 + x – y, z.

Figure 2
Packing diagram excluding hydrogen atoms.

Figure 3
All C—H⋯π interactions, shown as dashed lines, in two adjacent dimeric units. Hydrogen atoms not involved in interactions are omitted for clarity. Symmetry codes: (i) −x, −y, 1 − z; (ii) y, y − x, 1 − z; (iii) y − x, −x, z; (iv) −y, x − y, z; (v) x − y, x, 1 − z; (vi) $[{2\over 3}]$ − y + x, $[{1\over 3}]$ + x, $[{4\over 3}]$ − z; (vii) $[{2\over 3}]$ − x, $[{1\over 3}]$ − y, $[{4\over 3}]$ − z; (viii) $[{2\over 3}]$ + y, $[{1\over 3}]$ − x + y, $[{4\over 3}]$ − z; (ix) $[{2\over 3}]$ + x, $[{1\over 3}]$ + y, $[{1\over 3}]$ + z; (x) $[{2\over 3}]$ + y −x, $[{1\over 3}]$ − x, $[{1\over 3}]$ + z; (xi) $[{2\over 3}]$ − y, $[{1\over 3}]$ + x −y, $[{1\over 3}]$ + z.

Synthesis and crystallization

Tris(4-methoxyphenyl)stibine is obtained regularly as a side product of a reaction of the corresponding Grignard reagent with SbF₆ salts (Böhm et al., 2018). Intentional synthesis of the title product: SbCl₃ (69.1 mg, 303 µmol) was dissolved in dry THF (2 ml) and the obtained clear solution was cooled to −77°C. para-Methoxyphenyl magnesium bromide (0.5 M in THF, 2.0 ml, 211 mg, 1.00 mmol, 3.30 equiv.) was added dropwise to the white suspension and the mixture was allowed to slowly warm up to r.t. overnight. The grey suspension was quenched with sat. aq. NH₄Cl solution (3.0 ml). The aqueous phase was extracted with DCM (20 ml). The organic phase was dried over MgSO₄, and concentrated in vacuo. The crude product was purified by flash column chromatography (hexane: DCM; 90: 10→100: 0) and the title compound was obtained as a white solid (38.9 mg, 87.8 µmol, 29%). Colourless block-like crystals of the title compound were obtained by the diffusion method (DCM/pentane) at 4°C over a duration of two days.

¹H NMR (300 MHz, CD₂Cl₂ p.p.m.) δ = 3.79 (s, 9H), 6.89 (d, J = 8.7 Hz, 6H), 7.34 (d, J = 8.7 Hz, 6H). ¹³C NMR (126 MHz, CD₂Cl₂ p.p.m.) δ = 55.6, 115.1, 129.6, 137.7, 160.6. IR (ATR, cm⁻¹): 3008.4, 2962.1, 2922.6, 2834.8, 1580.4, 1561.1, 1487.8, 1459.8, 1450.2, 1435.7, 1393.3, 1373.1, 1306.5, 1277.6, 1235.2, 1175.4, 1118.5, 1100.2, 1062.6, 1044.3, 1025.0, 1002.8, 965.2, 941.1, 829.2, 816.7, 785.9, 739.6, 710.6, 584.3, 518.8. M.p. 356 K. HRMS: (ESI-pos.) calculated for C₂₁H₂₁Sb [M + Na]⁺ = 465.0421; found = 465.0401.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₂₁H₂₁O₃Sb
M_r	443.13
Crystal system, space group	Trigonal, R $[\overline{3}]$
Temperature (K)	298
a, c (Å)	13.1612 (5), 19.0063 (7)
V (Å³)	2851.1 (2)
Z	6.0
Radiation type	Mo Kα
μ (mm⁻¹)	1.47
Crystal size (mm)	0.25 × 0.23 × 0.23

Data collection
Diffractometer	Bruker D8 Venture PHOTON-II
Absorption correction	Multi-scan (SADABS; Bruker, 2016 )
T_min, T_max	0.686, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	18268, 2098, 1975
R_int	0.027
(sin θ/λ)_max (Å⁻¹)	0.736

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.025, 0.062, 1.09
No. of reflections	2098
No. of parameters	77
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.78, −0.91
Computer programs: APEX3 (Bruker, 2017 ), SAINT (Bruker, 2016), SHELXT (Sheldrick, 2015a ), SHELXL (Sheldrick, 2015b ) and OLEX2 (Dolomanov et al., 2009 ).

Structural data

CCDC reference: 1854911

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314618009896/sj4185sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314618009896/sj4185Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314618009896/sj4185Isup3.cml

checkCIF report

Computing details top

Data collection: APEX3 (Bruker, 2017); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Tris(4-methoxyphenyl)stibine top

Crystal data top

C₂₁H₂₁O₃Sb	D_x = 1.548 Mg m⁻³
M_r = 443.13	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3	Cell parameters from 3409 reflections
a = 13.1612 (5) Å	θ = 3.7–27.4°
c = 19.0063 (7) Å	µ = 1.47 mm⁻¹
V = 2851.1 (2) Å³	T = 298 K
Z = 6.0	Block, colourless
F(000) = 1332	0.25 × 0.23 × 0.23 mm

Data collection top

Bruker D8 Venture PHOTON-II diffractometer	1975 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.027
Absorption correction: multi-scan (SADABS; Bruker, 2016)	θ_max = 31.5°, θ_min = 3.7°
T_min = 0.686, T_max = 1.000	h = −19→19
18268 measured reflections	k = −15→19
2098 independent reflections	l = −27→27

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.025	H-atom parameters constrained
wR(F²) = 0.062	w = 1/[σ²(F_o²) + (0.0229P)² + 3.1602P] where P = (F_o² + 2F_c²)/3
S = 1.09	(Δ/σ)_max = 0.001
2098 reflections	Δρ_max = 0.78 e Å⁻³
77 parameters	Δρ_min = −0.91 e Å⁻³
0 restraints

Special details top

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. 1. Fixed Uiso At 1.2 times of: All C(H) groups At 1.5 times of: All C(H,H,H) groups 2.a Aromatic/amide H refined with riding coordinates: C2(H2), C3(H3), C5(H5), C6(H6) 2.b Idealized Me refined as rotating group: C7(H7A,H7B,H7C)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Sb1	0.000000	0.000000	0.70199 (2)	0.05031 (8)
O1	0.31482 (13)	0.46412 (12)	0.52928 (8)	0.0612 (3)
C1	0.10752 (15)	0.15805 (14)	0.64366 (8)	0.0455 (3)
C2	0.06716 (15)	0.18896 (15)	0.58391 (9)	0.0467 (3)
H2	−0.009131	0.139453	0.568436	0.056*
C3	0.13748 (15)	0.29087 (15)	0.54735 (9)	0.0467 (3)
H3	0.108327	0.309508	0.507860	0.056*
C4	0.25205 (15)	0.36600 (14)	0.56940 (9)	0.0454 (3)
C5	0.29484 (16)	0.33758 (16)	0.62858 (10)	0.0527 (4)
H5	0.371393	0.386981	0.643654	0.063*
C6	0.22236 (16)	0.23488 (17)	0.66499 (10)	0.0530 (4)
H6	0.251288	0.216775	0.704800	0.064*
C7	0.4225 (2)	0.5548 (2)	0.55660 (17)	0.0869 (8)
H7A	0.451384	0.622751	0.527008	0.130*
H7B	0.478675	0.528568	0.557995	0.130*
H7C	0.410236	0.574304	0.603309	0.130*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Sb1	0.05679 (10)	0.05679 (10)	0.03736 (10)	0.02839 (5)	0.000	0.000
O1	0.0573 (7)	0.0504 (7)	0.0669 (8)	0.0201 (6)	−0.0086 (6)	0.0045 (6)
C1	0.0500 (8)	0.0458 (7)	0.0422 (7)	0.0252 (7)	−0.0075 (6)	−0.0062 (6)
C2	0.0463 (8)	0.0479 (8)	0.0461 (8)	0.0237 (7)	−0.0118 (6)	−0.0077 (6)
C3	0.0506 (8)	0.0488 (8)	0.0452 (8)	0.0282 (7)	−0.0117 (6)	−0.0061 (6)
C4	0.0481 (8)	0.0430 (7)	0.0486 (8)	0.0254 (6)	−0.0059 (6)	−0.0069 (6)
C5	0.0467 (8)	0.0524 (9)	0.0563 (9)	0.0227 (7)	−0.0152 (7)	−0.0080 (7)
C6	0.0557 (9)	0.0572 (9)	0.0482 (8)	0.0296 (8)	−0.0165 (7)	−0.0053 (7)
C7	0.0690 (14)	0.0602 (12)	0.0997 (19)	0.0084 (11)	−0.0174 (13)	0.0076 (12)

Geometric parameters (Å, º) top

Sb1—C1ⁱ	2.1483 (17)	C3—H3	0.9300
Sb1—C1	2.1483 (17)	C3—C4	1.391 (2)
Sb1—C1ⁱⁱ	2.1483 (17)	C4—C5	1.390 (2)
O1—C4	1.366 (2)	C5—H5	0.9300
O1—C7	1.418 (3)	C5—C6	1.388 (3)
C1—C2	1.398 (2)	C6—H6	0.9300
C1—C6	1.394 (2)	C7—H7A	0.9600
C2—H2	0.9300	C7—H7B	0.9600
C2—C3	1.377 (3)	C7—H7C	0.9600

C1ⁱ—Sb1—C1ⁱⁱ	95.77 (6)	O1—C4—C5	124.84 (16)
C1ⁱⁱ—Sb1—C1	95.77 (6)	C5—C4—C3	119.55 (16)
C1ⁱ—Sb1—C1	95.77 (6)	C4—C5—H5	120.3
C4—O1—C7	117.95 (17)	C6—C5—C4	119.46 (16)
C2—C1—Sb1	122.61 (12)	C6—C5—H5	120.3
C6—C1—Sb1	120.18 (12)	C1—C6—H6	119.0
C6—C1—C2	117.21 (16)	C5—C6—C1	121.96 (16)
C1—C2—H2	119.2	C5—C6—H6	119.0
C3—C2—C1	121.68 (15)	O1—C7—H7A	109.5
C3—C2—H2	119.2	O1—C7—H7B	109.5
C2—C3—H3	119.9	O1—C7—H7C	109.5
C2—C3—C4	120.13 (15)	H7A—C7—H7B	109.5
C4—C3—H3	119.9	H7A—C7—H7C	109.5
O1—C4—C3	115.60 (15)	H7B—C7—H7C	109.5

Symmetry codes: (i) −y, x−y, z; (ii) −x+y, −x, z.

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the C1–C6 benzene ring

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···Cg1ⁱⁱⁱ	0.93	3.11	3.849 (2)	138
C5—H5···Cg1^iv	0.93	2.91	3.814 (2)	165

Symmetry codes: (iii) −x+y+2/3, −x+1/3, z+4/3; (iv) x−y+1/3, x+2/3, −z+5/3.

Funding information

Funding for this research was provided by: Deutsche Forschungsgemeinschaft (grant No. AL 1348/7-1; grant No. INST 186/1237-1); Stiftung der Deutschen Wirtschaft (scholarship to Marvin J. Böhm).

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