Bis­[2-(2-hydroxy­phenoxy)­ethyl] ether methanol solvate

The title compound, 2,2′-(3-oxa­pentane-1,5-diyl­dioxy)­diphenol, crystallizes as a methanol solvate, C₁₆H₁₈O₅·CH₄O. The methanol mol­ecule, roughly perpendicular to the mean plane of the polyether molecule, is hydrogen bonded to the two polyether OH groups and to the central ether O atom. Possible C—H...π intermolecular interactions are present.

S1. Comment

In the course of our studies on complexes of catechol derivatives, we obtained the crystal structure of bis[2-(2-hydroxyphenoxy)ethyl]ether as a methanol solvate (I). The crystal structures of only two related compounds have been reported previously. One corresponds to the molecule with two methoxy groups in place of the OH ones in (I) (Chacko et al., 1984) and the other to the potassium picrate complex of the molecule with two carboxymethoxy substituents (Hughes et al., 1978). In the first of these, the catechol units are located trans to the central ether moiety, whereas in the second the arrangement is cis due to complexation to potassium ions.

The asymmetric unit of (I) comprises one bis[2-(2-hydroxyphenoxy)ethyl]ether and one methanol molecule (Fig. 1). The geometry of the former is cis due to the involvement of the methanol molecule in hydrogen bonding. The methanol hydroxyl proton is bound to the central ether-O atom whereas the methanol-O atom is hydrogen bonded to the two OH groups of the catechol units. The methanol O atom thus acts as a ring closure. The five atoms O1, O2, O3, O4 and O5 define a mean plane with a maximum deviation of 0.071 (1) Å, the methanol atom O6 lying 0.708 (1) Å from this plane. The situation is somewhat different in the hydrated form of the analogous compound with an ether chain longer by one O(CH₂)₂ unit (Suh et al., 1985), since in this case the array of O atoms is sufficiently large to encompass the water molecule close to its centre with, furthermore, one of the catechol hydroxyl proton involved in an intermolecular hydrogen bond.

The dihedral angle between the two aromatic rings in (I) is 117.76 (6)°, which gives the molecule a `butterfly' shape, the methanol molecule being located on the convex side. The O—C—C—O torsion angles in the ether part of the molecule are 61.4 (2) and -64.3 (2)° for O2—C7—C8—O3 and O3—C9—C10—O4, respectively, close to the ideal values for gauche angles, whereas the C—O—C—C torsion angles deviate from their ideal values of 0 or 180° by less than 10°.

The crystal packing contains an interesting feature. Molecules are related by the screw axis such that two protons of the ether chain (bound to C7 and C10) point towards the centroids of the aromatic rings of a neighbouring molecule. The H···centroid distances (2.56 and 2.58 Å) and the C—H···centroid angles (151 and 147°) indicate the possibility of weak CH···π interactions, at least on a geometrical basis (Jeffrey & Saenger, 1994).

S2. Experimental

Bis[2-(2-hydroxyphenoxy)ethyl]ether was synthesized according to a procedure previously reported (Kyba et al., 1977) and recrystallized from methanol.

S3. Refinement

The hydroxyl-H atoms of the methanol molecule and catechol units were found in the Fourier difference map and introduced as riding atoms with a displacement parameter equal to 1.2 times that of the parent atom. The O6—H6 bond length is slightly larger than usual, but was kept as found in the refinement. All other H atoms were introduced at calculated positions (CH 0.93, CH₂ 0.97, CH₃ 0.96 Å) as riding atoms with a displacement parameter equal to 1.2 (CH, CH₂) or 1.5 (CH₃) times that of the parent atom.

Computing details

Data collection: KappaCCD Software (Nonius, 1998); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL (Bruker, 1997) and PARST97 (Nardelli, 1995).

Figures

	Fig. 1. The title molecule (I) with the atomic numbering scheme. Hydrogen bonds are shown as dashed lines. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. The packing arrangement of (I). H atoms have been omitted for clarity, except those involved in hydrogen bonding and those on C atoms C7 and C10. Hydrogen bonds are shown as dashed lines. ### AUTHOR: please check this revised Figure caption ###

(I)

Crystal data

C16H18O5·CH4O	F(000) = 688
Mr = 322.35	Dx = 1.288 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 10.8638 (7) Å	Cell parameters from 6010 reflections
b = 9.6264 (5) Å	θ = 2.8–25.7°
c = 15.9399 (9) Å	µ = 0.10 mm^−1
β = 94.270 (3)°	T = 100 K
V = 1662.4 (2) Å^3	Parallelepiped, colourless
Z = 4	0.30 × 0.30 × 0.25 mm

Data collection

Nonius KappaCCD area detector diffractometer	2190 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.047
Graphite monochromator	θmax = 25.7°, θmin = 2.8°
Detector resolution: 18 pixels mm^-1	h = −13→13
ϕ scans	k = −11→11
6010 measured reflections	l = −19→19
3129 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)] = 0.045	Hydrogen site location: see text
wR(F^2) = 0.119	See text
S = 1.02	w = 1/[σ^2(Fo^2) + (0.055P)^2 + 0.291P] where P = (Fo^2 + 2Fc^2)/3
3129 reflections	(Δ/σ)max = 0.001
209 parameters	Δρmax = 0.16 e Å^−3
0 restraints	Δρmin = −0.23 e Å^−3

Special details

Experimental. crystal-to-detector distance 28 mm

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. A 180° range in ϕ was scanned during data collection, with 2° ϕ steps. Crystal-to-detector distance fixed at 28 mm.

Structure solved by direct methods and subsequent Fourier-difference synthesis. All non-hydrogen atoms were refined with anisotropic displacement parameters. The hydrogen atoms bound to O atoms have been found on the Fourier-difference map and introduced as riding atoms with an isotropic displacement parameter equal to 1.2 times that of the parent atom. All other hydrogen atoms were introduced at calculated positions as riding atoms with an isotropic displacement parameter equal to 1.2 (CH, CH2) or 1.5 (CH3) times that of the parent atom.

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

	x	y	z	Uiso*/Ueq
O1	0.49490 (13)	0.21467 (15)	−0.00582 (9)	0.0362 (4)
H1	0.4672	0.2636	0.0372	0.043*
O2	0.62048 (11)	0.35906 (13)	0.11635 (8)	0.0272 (3)
O3	0.49235 (12)	0.44762 (13)	0.24994 (8)	0.0270 (3)
O4	0.24949 (11)	0.36477 (13)	0.27016 (8)	0.0270 (3)
O5	0.14137 (12)	0.20741 (14)	0.14692 (8)	0.0320 (3)
H5	0.2210	0.2565	0.1439	0.038*
C1	0.61996 (18)	0.1992 (2)	0.00656 (12)	0.0279 (4)
C2	0.67928 (18)	0.1102 (2)	−0.04486 (12)	0.0332 (5)
H2	0.6336	0.0623	−0.0872	0.040*
C3	0.80598 (19)	0.0910 (2)	−0.03439 (13)	0.0332 (5)
H3	0.8450	0.0308	−0.0696	0.040*
C4	0.87403 (19)	0.16201 (19)	0.02877 (12)	0.0309 (5)
H4	0.9590	0.1490	0.0362	0.037*
C5	0.81592 (18)	0.2529 (2)	0.08129 (12)	0.0276 (4)
H5A	0.8618	0.3004	0.1237	0.033*
C6	0.68984 (17)	0.27176 (19)	0.06988 (11)	0.0249 (4)
C7	0.68325 (18)	0.4313 (2)	0.18555 (12)	0.0287 (4)
H7A	0.7524	0.4834	0.1666	0.034*
H7B	0.7143	0.3659	0.2283	0.034*
C8	0.59168 (18)	0.5277 (2)	0.22049 (13)	0.0299 (5)
H8A	0.6313	0.5812	0.2665	0.036*
H8B	0.5600	0.5919	0.1772	0.036*
C9	0.40896 (18)	0.53039 (19)	0.29455 (12)	0.0293 (5)
H9A	0.3629	0.5922	0.2558	0.035*
H9B	0.4549	0.5865	0.3366	0.035*
C10	0.32203 (17)	0.4364 (2)	0.33606 (12)	0.0276 (4)
H10A	0.2689	0.4901	0.3701	0.033*
H10B	0.3678	0.3703	0.3721	0.033*
C11	0.16499 (17)	0.26858 (18)	0.29434 (12)	0.0253 (4)
C12	0.11061 (17)	0.18857 (19)	0.22800 (12)	0.0261 (4)
C13	0.02417 (17)	0.0889 (2)	0.24427 (13)	0.0315 (5)
H13	−0.0126	0.0361	0.2004	0.038*
C14	−0.00810 (18)	0.0672 (2)	0.32610 (14)	0.0340 (5)
H14	−0.0666	0.0003	0.3368	0.041*
C15	0.04669 (19)	0.1451 (2)	0.39130 (13)	0.0336 (5)
H15	0.0255	0.1296	0.4460	0.040*
C16	0.13327 (18)	0.2464 (2)	0.37586 (13)	0.0310 (5)
H16	0.1696	0.2990	0.4199	0.037*
O6	0.35039 (12)	0.34310 (13)	0.10620 (8)	0.0294 (3)
H6	0.4092	0.3686	0.1574	0.035*
C17	0.3205 (2)	0.4714 (2)	0.06243 (14)	0.0365 (5)
H17A	0.2772	0.5317	0.0981	0.055*
H17B	0.2692	0.4521	0.0121	0.055*
H17C	0.3951	0.5158	0.0480	0.055*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0277 (7)	0.0470 (9)	0.0331 (8)	0.0022 (7)	−0.0028 (6)	−0.0137 (7)
O2	0.0268 (7)	0.0281 (7)	0.0265 (7)	−0.0008 (6)	0.0000 (6)	−0.0054 (6)
O3	0.0262 (7)	0.0256 (7)	0.0296 (7)	−0.0028 (6)	0.0047 (5)	−0.0045 (6)
O4	0.0278 (7)	0.0266 (7)	0.0262 (7)	−0.0057 (6)	0.0001 (5)	−0.0017 (6)
O5	0.0315 (7)	0.0357 (8)	0.0285 (8)	−0.0078 (6)	0.0004 (6)	−0.0019 (6)
C1	0.0266 (10)	0.0298 (10)	0.0270 (10)	−0.0009 (9)	−0.0006 (8)	0.0004 (8)
C2	0.0351 (11)	0.0345 (11)	0.0299 (11)	−0.0025 (10)	0.0014 (9)	−0.0076 (9)
C3	0.0358 (11)	0.0341 (11)	0.0304 (11)	0.0027 (10)	0.0074 (9)	−0.0025 (9)
C4	0.0287 (10)	0.0307 (10)	0.0336 (11)	0.0018 (9)	0.0046 (8)	0.0026 (9)
C5	0.0279 (10)	0.0267 (10)	0.0280 (10)	−0.0024 (9)	0.0012 (8)	0.0014 (8)
C6	0.0284 (10)	0.0235 (9)	0.0231 (10)	0.0011 (9)	0.0044 (8)	0.0013 (8)
C7	0.0293 (10)	0.0295 (10)	0.0271 (11)	−0.0053 (9)	0.0003 (8)	−0.0049 (8)
C8	0.0298 (10)	0.0275 (10)	0.0327 (11)	−0.0066 (9)	0.0051 (9)	−0.0046 (8)
C9	0.0293 (10)	0.0245 (10)	0.0342 (11)	0.0000 (9)	0.0041 (9)	−0.0066 (8)
C10	0.0264 (10)	0.0280 (10)	0.0280 (11)	−0.0013 (9)	−0.0001 (8)	−0.0071 (8)
C11	0.0221 (9)	0.0208 (9)	0.0332 (11)	0.0028 (8)	0.0034 (8)	0.0013 (8)
C12	0.0231 (9)	0.0257 (9)	0.0290 (10)	0.0018 (8)	−0.0005 (8)	0.0006 (8)
C13	0.0244 (11)	0.0286 (10)	0.0408 (12)	−0.0021 (9)	−0.0016 (9)	−0.0030 (9)
C14	0.0274 (10)	0.0289 (11)	0.0466 (13)	−0.0008 (9)	0.0082 (9)	0.0013 (10)
C15	0.0332 (11)	0.0311 (11)	0.0377 (12)	0.0002 (10)	0.0100 (9)	0.0006 (9)
C16	0.0316 (11)	0.0292 (10)	0.0326 (11)	0.0016 (9)	0.0050 (9)	−0.0045 (9)
O6	0.0311 (7)	0.0317 (7)	0.0250 (7)	−0.0014 (6)	−0.0008 (6)	0.0027 (6)
C17	0.0340 (11)	0.0398 (12)	0.0356 (12)	0.0055 (10)	0.0019 (9)	0.0088 (10)

Geometric parameters (Å, º)

O1—C1	1.366 (2)	C8—H8A	0.9700
O1—H1	0.90	C8—H8B	0.9700
O2—C6	1.380 (2)	C9—C10	1.497 (3)
O2—C7	1.433 (2)	C9—H9A	0.9700
O3—C8	1.433 (2)	C9—H9B	0.9700
O3—C9	1.434 (2)	C10—H10A	0.9700
O4—C11	1.379 (2)	C10—H10B	0.9700
O4—C10	1.441 (2)	C11—C16	1.385 (3)
O5—C12	1.371 (2)	C11—C12	1.403 (3)
O5—H5	0.99	C12—C13	1.381 (3)
C1—C2	1.378 (3)	C13—C14	1.391 (3)
C1—C6	1.403 (3)	C13—H13	0.9300
C2—C3	1.386 (3)	C14—C15	1.380 (3)
C2—H2	0.9300	C14—H14	0.9300
C3—C4	1.384 (3)	C15—C16	1.390 (3)
C3—H3	0.9300	C15—H15	0.9300
C4—C5	1.394 (3)	C16—H16	0.9300
C4—H4	0.9300	O6—C17	1.444 (2)
C5—C6	1.380 (3)	O6—H6	1.03
C5—H5A	0.9300	C17—H17A	0.9600
C7—C8	1.498 (3)	C17—H17B	0.9600
C7—H7A	0.9700	C17—H17C	0.9600
C7—H7B	0.9700
C1—O1—H1	109.4	O3—C9—H9A	109.9
C6—O2—C7	117.45 (14)	C10—C9—H9A	109.9
C8—O3—C9	112.47 (13)	O3—C9—H9B	109.9
C11—O4—C10	117.19 (14)	C10—C9—H9B	109.9
C12—O5—H5	112.5	H9A—C9—H9B	108.3
O1—C1—C2	119.06 (17)	O4—C10—C9	107.20 (15)
O1—C1—C6	121.91 (17)	O4—C10—H10A	110.3
C2—C1—C6	119.03 (18)	C9—C10—H10A	110.3
C1—C2—C3	121.01 (19)	O4—C10—H10B	110.3
C1—C2—H2	119.5	C9—C10—H10B	110.3
C3—C2—H2	119.5	H10A—C10—H10B	108.5
C4—C3—C2	119.57 (19)	O4—C11—C16	125.65 (17)
C4—C3—H3	120.2	O4—C11—C12	114.19 (16)
C2—C3—H3	120.2	C16—C11—C12	120.16 (18)
C3—C4—C5	120.35 (19)	O5—C12—C13	119.08 (17)
C3—C4—H4	119.8	O5—C12—C11	121.31 (17)
C5—C4—H4	119.8	C13—C12—C11	119.61 (18)
C6—C5—C4	119.53 (18)	C12—C13—C14	120.19 (19)
C6—C5—H5A	120.2	C12—C13—H13	119.9
C4—C5—H5A	120.2	C14—C13—H13	119.9
C5—C6—O2	125.84 (17)	C15—C14—C13	120.00 (19)
C5—C6—C1	120.50 (17)	C15—C14—H14	120.0
O2—C6—C1	113.66 (16)	C13—C14—H14	120.0
O2—C7—C8	107.20 (15)	C14—C15—C16	120.50 (19)
O2—C7—H7A	110.3	C14—C15—H15	119.8
C8—C7—H7A	110.3	C16—C15—H15	119.7
O2—C7—H7B	110.3	C11—C16—C15	119.53 (19)
C8—C7—H7B	110.3	C11—C16—H16	120.2
H7A—C7—H7B	108.5	C15—C16—H16	120.2
O3—C8—C7	109.00 (15)	C17—O6—H6	106.5
O3—C8—H8A	109.9	O6—C17—H17A	109.5
C7—C8—H8A	109.9	O6—C17—H17B	109.5
O3—C8—H8B	109.9	H17A—C17—H17B	109.5
C7—C8—H8B	109.9	O6—C17—H17C	109.5
H8A—C8—H8B	108.3	H17A—C17—H17C	109.5
O3—C9—C10	109.02 (14)	H17B—C17—H17C	109.5
O1—C1—C2—C3	−179.80 (19)	C8—O3—C9—C10	−169.97 (15)
C6—C1—C2—C3	0.5 (3)	C11—O4—C10—C9	178.05 (14)
C1—C2—C3—C4	0.1 (3)	O3—C9—C10—O4	−64.26 (19)
C2—C3—C4—C5	−0.4 (3)	C10—O4—C11—C16	8.1 (2)
C3—C4—C5—C6	−0.1 (3)	C10—O4—C11—C12	−171.19 (16)
C4—C5—C6—O2	−179.29 (16)	O4—C11—C12—O5	0.1 (3)
C4—C5—C6—C1	0.7 (3)	C16—C11—C12—O5	−179.30 (17)
C7—O2—C6—C5	−3.5 (3)	O4—C11—C12—C13	−179.81 (15)
C7—O2—C6—C1	176.49 (16)	C16—C11—C12—C13	0.8 (3)
O1—C1—C6—C5	179.39 (17)	O5—C12—C13—C14	179.62 (18)
C2—C1—C6—C5	−0.9 (3)	C11—C12—C13—C14	−0.5 (3)
O1—C1—C6—O2	−0.6 (3)	C12—C13—C14—C15	−0.3 (3)
C2—C1—C6—O2	179.08 (16)	C13—C14—C15—C16	0.7 (3)
C6—O2—C7—C8	175.01 (14)	O4—C11—C16—C15	−179.68 (17)
C9—O3—C8—C7	172.19 (15)	C12—C11—C16—C15	−0.4 (3)
O2—C7—C8—O3	61.43 (19)	C14—C15—C16—C11	−0.4 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O6	0.90	1.90	2.7566 (19)	158
O5—H5···O6	0.99	1.78	2.7392 (18)	163
O6—H6···O3	1.03	1.84	2.8485 (18)	167