Crystal structure of 2,4-di-tert-butyl-6-(hy­droxy­methyl)­phenol

Aranburu Leiva, A.I.; Benjamin, S.L.; Langley, S.K.; Mewis, R.E.

doi:10.1107/S2056989016016753

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ISSN: 2056-9890

Volume 72| Part 11| November 2016| Pages 1614-1617

https://doi.org/10.1107/S2056989016016753

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Crystal structure of 2,4-di-tert-butyl-6-(hydroxymethyl)phenol

Ane I. Aranburu Leiva,^a Sophie L. Benjamin,^b Stuart K. Langley ^a and Ryan E. Mewis ^a ^*

^aSchool of Science and the Environment, Division of Chemistry and Environmental Science, Manchester Metropolitan University, John Dalton Building, Chester St, Manchester, M1 5GD, England, and ^bSchool of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, England
^*Correspondence e-mail: r.mewis@mmu.ac.uk

Edited by A. J. Lough, University of Toronto, Canada (Received 23 September 2016; accepted 19 October 2016; online 25 October 2016)

The title compound, C₁₅H₂₄O₂, is an example of a phenol-based pendant-arm precursor. In the molecule, the phenol hydroxy group participates in an intramolecular O—H⋯O hydrogen bond with the pendant alcohol group, forming an S(6) ring. This ring adopts a half-chair conformation. In the crystal, O—H⋯O hydrogen bonds connect molecules related by the 3₁ screw axes, forming chains along the c axis. The C—C—O angles for the hydroxy groups are different as a result of the type of hybridization for the C atoms that are involved in these angles. The C—C—O angle for the phenol hydroxy group is 119.21 (13)°, while the angle within the pendant alcohol is 111.99 (13)°. The bond length involving the phenolic oxygen is 1.3820 (19) Å, which contrasts with that of the alcoholic oxygen which is 1.447 (2) Å. The former is conjugated with the aromatic ring and so leads to the observed shorter bond length.

Keywords: crystal structure; O—H⋯O hydrogen bonding; intra- and intermolecular hydrogen bonding; pendent arm.

CCDC reference: 1510636

1. Chemical context

The addition of pendent arms to ligands, which possess donor atoms that are capable of ligating to a metal ion, aid the stabilization of the resulting complex formed. In particular, the use of phenol-based ligands are of interest because they are used to form stable phenoxyl radicals, which are found in some enzymatic active sites, such as photosystem II and galactose oxidase (Rogers & Dooley, 2003 ; Pujols-Ayala & Barry, 2004 ). Synthesis of pendent arms containing phenolate moieties have been used for the creation of biomimetic complexes and for the study of their redox properties (Zhu et al., 1996 ; Kimura et al., 2001 ; Esteves et al., 2013 ; Sokolowski et al., 1997 ). The creation of pendent arms that possess functional groups, which can be easily manipulated to give possible tethering points (such as the transformation of an alcohol to the corresponding alkyl halide), or groups that are easily protected to prevent unwanted side reactions are, therefore, highly desirable.

As part of our work on the synthesis of macrocyclic ligand systems bearing phenolate pendent arms, we report the crystal structure of 2,4-di-tert-butyl-6-hydroxymethylphenol, (I), which is an intermediary in a pendent-arm synthesis.

2. Structural commentary

The molecule of (I) possesses an intramolecular hydrogen bond (Table 1). This interaction does not cause any sizable deviation from the idealized bond angle, as the bond angle for C6—C15—O2 is 111.99 (13)°, whilst the bond angle for C6—C1—O1 is 119.21 (13)°. Furthermore, the formation of an intramolecular hydrogen bond within the structure creates a six-membered ring system that involves C1, C6, C15, O2, H1O1 and O1. This six-membered ring has a half-chair conformation. The phenolic C—O bond length is 1.3820 (19) Å, which is shorter than the alcoholic C—O bond length [1.447 (2) Å] due to conjugation with the aromatic ring. The aromatic ring is planar, as expected, and has internal bond angles that range from 116.49 (14) to 123.95 (14)°. The bond lengths from the quaternary atoms of the tert-butyl group to the nearest aromatic ring carbon are very similar (the average bond length is 1.54 Å).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H1O2⋯O2ⁱ	0.91 (2)	1.75 (2)	2.6636 (14)	178 (2)
O1—H1O1⋯O2	0.84 (2)	2.03 (2)	2.7706 (18)	146 (2)
Symmetry code: (i) $[-y+1, x-y, z+{\script{1\over 3}}]$ .

3. Supramolecular features

In the crystal structure of (I) (Fig. 1), molecules are linked by intermolecular hydrogen bonds that are much shorter than the intramolecular hydrogen bonds (see Table 1). Intermolecular hydrogen bonds are formed between molecules that are related by a 3₁ screw axis which generates chains along the c-axis direction (Figs. 2 and 3). The intermolecular hydrogen bond is stronger than the intramolecular bond due to collinearity between the proton donor group (O2—H1O2) and the proton acceptor (O2ⁱ). The bond angle for O2—H1O2⋯O2ⁱ is 178 (2)°, which contrasts strongly with the weaker intramolecular hydrogen bond, which is 146 (2)° (O1—H1O1⋯O2). The presence of intermolecular hydrogen bonding is the only interaction that stabilizes the 1D structure, as there are no π–π stacking interactions present; the aromatic rings are separated by more than 6 Å.

Figure 1
The molecular structure of compound (I)

, showing the atom labelling and displacement ellipsoids drawn at the 50% probability level. The intramolecular hydrogen bond is shown by the dashed bond.

Figure 2
The crystal packing of compound (I)

, viewed along the c-axis direction. The hydrogen bonds are shown as dashed lines.

Figure 3
The crystal packing of compound (I)

showing the helical chains along the c axis. Hydrogen bonds are shown as dashed lines.

4. Database survey

A search of the Cambridge Structural Database (Version 5.37, update February 2016; Groom et al., 2016 ) for the substructure of 2,4-di-tert-butyl-6-hydroxymethylphenol yielded 29 hits (the carbon of the CH₂ group was restricted to have a coordination of four atoms, and the phenolic oxygen two atoms). Of these 29 hits, 14 were organic compounds; the remainder were all metal complexes. A number of compounds used the same molecular motif to form ethers via the alcoholic oxygen [AVOPOR and AVOQET (Huang et al., 2010 ); BERLIV, BERLOB, BURLAH and BERMAO (Huang et al., 2013 ); WUZJAE and WUZHOW (Audouin et al., 2015 )]. A further sub-set of interest was where the two hydrogen atoms of the CH₂ group of (I) have been replaced by CF₃/C₆F₅ groups to coordinate to titanium(IV) centres [ZUNWOW and ZUNWUC (Tuskaev et al., 2015 ); XEMBAU and XEMREY (Solov'ev et al., 2011 )]. ZUNWOW is noteworthy because fluorine also acts as a ligand to a coordinated lithium ion. Two oxazole structures that contain the title compound were also identified [KUTQUM (Campbell et al., 2010 ); LUYSIU (Błocka et al., 2010 )], although neither used (I) as a starting material. The only structure that utilizes 2,4-di-tert-butyl-6-hydroxymethylphenol without modification is a complex that contains two titanium(IV) centres, four 2,4-di-tert-butyl-6-hydroxymethylphenol ligands and two chloride ligands (BAFFOG; Gagieva et al., 2014 ). Two of the 2,4-di-tert-butyl-6-hydroxymethylphenol ligands display bridging through the alcoholic oxygen to both Ti^IV centres. The C—O bond lengths are comparable to those of (I); the phenolic C—O bond length in BAFFOG shows the largest difference in that it contracts by 0.015 Å relative to (I). Furthermore, the bond lengths of the six-membered ring that is formed between the ligand and the Ti^IV centre also closely resembles that of (I); the only noteworthy difference between the two structures are the two bond lengths that involve oxygen to either Ti^IV or H1O1. In the former they are 2.003 and 1.832 Å whereas in (I) they are 2.03 (2) and 0.84 (2) Å.

5. Synthesis and crystallization

The synthesis of 2,4-di-tert-butyl-6-hydroxymethylphenol is based on a reported literature procedure (Wang et al., 2014 ). 2,4-Di-tert-butylphenol (5 g, 0.024 mol) and LiOH·H₂O (0.083 g, 0.002 mol) were dissolved in methanol (10 mL), and a suspension of paraformaldehyde (4.50 g, 0.15 mol) in methanol (10 mL) was added at room temperature. The reaction mixture was heated to reflux for 24 hr. After being allowed to cool to room temperature, the solvent was removed under reduced pressure and the white residue was dissolved in diethyl ether. The organic layer was washed with water (3 x 50 mL). The organic layer was collected and dried with magnesium sulfate. The solvent was removed by rotary evaporation to yield a white powder (2.3 g, 40%). Part of the purified product was re-dissolved in n-hexane and placed in a refrigerator. After several days, colourless needle-like crystals were obtained. ¹H NMR (CDCl₃, 400 MHz): δ 7.55 (s, 1H, CH₂OH), 7.28 (d, 1H, J = 2.52 Hz, ArH), 6.89 (d, 1H, J = 2.52 Hz, ArH), 4.84 (s, 2H, CH₂OH), 1.41 (s, 9H, ^tBu), 1.29 (s, 9H, ^tBu); ¹³C NMR (CDCl₃, 100 MHz): δ 153.21, 141.69, 136.60, 124.19, 124.04, 122.70 (C_arom), 66.00 (CH₂), 35.04, 34.30 [C(^tBu)], 31.69, 29.75 [Me(^tBu)]. IR (KBr pellet, cm⁻¹): 3530 (w), 3424 (w), 3175 (w, br), 2954 (s), 2905 (s), 2866 (m), 1067 (w), 1506 (s), 1481 (s), 1463 (s), 1445 (s), 1417 (m), 1391 (s), 1361 (s), 1301 (w), 1278 (w), 1250 (w), 1227 (s), 1201 (s), 1163 (w), 1125 (m), 1084 (w), 1026 (s), 942 (s), 927 (s), 879 (s), 823 (m), 797 (m), 763 (m), 723, (m), 654 (m).

6. Refinement details

Crystal data, data collection and structure refinement details are summarized in Table 2. All hydrogen atoms are placed in calculated positions [C—H = 0.98–0.99Å; U_iso(H) = 1.2 or 1.5U_eq(C)], except for H1O1 and H1O2 which were located in a difference map and their positions freely refined with U_iso(H) = 0.05 for both. The absolute structure could not be determined from the X-ray data.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₅H₂₄O₂
M_r	236.34
Crystal system, space group	Trigonal, P3₁
Temperature (K)	123
a, c (Å)	14.4357 (9), 6.0404 (5)
V (Å³)	1090.11 (13)
Z	3
Radiation type	Mo Kα
μ (mm⁻¹)	0.07
Crystal size (mm)	0.5 × 0.1 × 0.05

Data collection
Diffractometer	Agilent Xcalibur
Absorption correction	Multi-scan (CrysAlis PRO; Agilent, 2014 )
T_min, T_max	0.992, 0.997
No. of measured, independent and observed [I > 2σ(I)] reflections	6245, 3097, 2883
R_int	0.025
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.089, 1.08
No. of reflections	3097
No. of parameters	166
No. of restraints	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.20, −0.22
Computer programs: CrysAlis PRO (Agilent, 2014), SHELXS97 and SHELXL97 (Sheldrick, 2008 ), X-SEED (Barbour, 2001 ) and CAMERON (Watkin et al., 1996 ).

Supporting information

CCDC reference: 1510636

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989016016753/lh5825sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989016016753/lh5825Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989016016753/lh5825Isup3.cml

checkCIF report

Computing details top

Data collection: CrysAlis PRO (Agilent, 2014); cell refinement: CrysAlis PRO (Agilent, 2014); data reduction: CrysAlis PRO (Agilent, 2014); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: CAMERON (Watkin et al., 1996).

2,4-Di-tert-butyl-6-(hydroxymethyl)phenol top

Crystal data top

C₁₅H₂₄O₂	D_x = 1.080 Mg m⁻³
M_r = 236.34	Mo Kα radiation, λ = 0.71073 Å
Trigonal, P3₁	Cell parameters from 9833 reflections
a = 14.4357 (9) Å	θ = 3.1–27.5°
c = 6.0404 (5) Å	µ = 0.07 mm⁻¹
V = 1090.11 (13) Å³	T = 123 K
Z = 3	Needle, colourless
F(000) = 390	0.5 × 0.1 × 0.05 mm

Data collection top

Agilent Xcalibur diffractometer	3097 independent reflections
Radiation source: fine-focus sealed tube	2883 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.025
Detector resolution: 15.9832 pixels mm^-1	θ_max = 27.5°, θ_min = 3.3°
scans in φ and ω	h = −18→17
Absorption correction: multi-scan (CrysAlisPro; Agilent, 2014)	k = −17→18
T_min = 0.992, T_max = 0.997	l = −7→7
6245 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.089	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ²(F_o²) + (0.0403P)² + 0.0827P] where P = (F_o² + 2F_c²)/3
3097 reflections	(Δ/σ)_max = 0.001
166 parameters	Δρ_max = 0.20 e Å⁻³
1 restraint	Δρ_min = −0.22 e Å⁻³

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. 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 (Å²) top

	x	y	z	U_iso*/U_eq
O2	0.70639 (10)	0.41386 (10)	−0.00481 (18)	0.0260 (3)
C3	0.73856 (12)	0.70473 (12)	0.5036 (2)	0.0199 (3)
H3	0.7539	0.7548	0.6196	0.024*
C4	0.63425 (12)	0.64968 (12)	0.4213 (2)	0.0204 (3)
O1	0.87583 (9)	0.59921 (11)	0.1671 (2)	0.0314 (3)
C6	0.69423 (12)	0.56297 (12)	0.1580 (2)	0.0218 (3)
C2	0.82219 (12)	0.69053 (12)	0.4252 (2)	0.0216 (3)
C1	0.79714 (12)	0.61721 (13)	0.2511 (2)	0.0223 (3)
C11	0.54260 (12)	0.66266 (13)	0.5165 (3)	0.0228 (3)
C5	0.61420 (12)	0.57839 (13)	0.2466 (3)	0.0219 (3)
H5	0.5440	0.5395	0.1871	0.026*
C7	0.93578 (13)	0.75319 (14)	0.5246 (3)	0.0269 (4)
C15	0.67162 (14)	0.49097 (13)	−0.0400 (3)	0.0260 (4)
H15A	0.5939	0.4526	−0.0708	0.031*
H15B	0.7088	0.5352	−0.1711	0.031*
C13	0.49041 (14)	0.69333 (15)	0.3305 (3)	0.0319 (4)
H13A	0.4310	0.6999	0.3913	0.048*
H13B	0.4634	0.6378	0.2159	0.048*
H13C	0.5436	0.7618	0.2658	0.048*
C14	0.45901 (13)	0.55618 (14)	0.6205 (3)	0.0323 (4)
H14A	0.4920	0.5375	0.7414	0.048*
H14B	0.4322	0.4998	0.5078	0.048*
H14C	0.3995	0.5633	0.6786	0.048*
C12	0.58201 (14)	0.74938 (15)	0.6963 (3)	0.0313 (4)
H12A	0.6358	0.8181	0.6333	0.047*
H12B	0.6139	0.7300	0.8181	0.047*
H12C	0.5216	0.7555	0.7522	0.047*
C8	0.96891 (15)	0.67363 (16)	0.6149 (3)	0.0358 (4)
H8A	1.0399	0.7134	0.6827	0.054*
H8B	0.9709	0.6298	0.4929	0.054*
H8C	0.9169	0.6272	0.7260	0.054*
C10	0.94193 (14)	0.82504 (15)	0.7178 (3)	0.0348 (4)
H10A	1.0150	0.8627	0.7767	0.052*
H10B	0.8923	0.7810	0.8347	0.052*
H10C	0.9224	0.8773	0.6655	0.052*
C9	1.01503 (14)	0.82514 (17)	0.3459 (3)	0.0420 (5)
H9A	0.9933	0.8752	0.2905	0.063*
H9B	1.0154	0.7807	0.2235	0.063*
H9C	1.0869	0.8653	0.4097	0.063*
H1O2	0.6651 (18)	0.3735 (18)	0.111 (4)	0.050*
H1O1	0.8464 (19)	0.5408 (18)	0.099 (4)	0.050*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O2	0.0308 (6)	0.0292 (6)	0.0208 (6)	0.0170 (5)	0.0048 (5)	0.0005 (5)
C3	0.0212 (7)	0.0180 (7)	0.0200 (7)	0.0095 (6)	0.0007 (6)	0.0012 (6)
C4	0.0197 (7)	0.0198 (8)	0.0213 (8)	0.0095 (6)	0.0013 (6)	0.0040 (6)
O1	0.0226 (6)	0.0407 (8)	0.0319 (7)	0.0166 (6)	0.0016 (5)	−0.0089 (6)
C6	0.0256 (8)	0.0202 (8)	0.0193 (8)	0.0113 (7)	0.0008 (6)	0.0021 (6)
C2	0.0194 (8)	0.0229 (8)	0.0191 (8)	0.0079 (7)	0.0022 (6)	0.0036 (6)
C1	0.0208 (8)	0.0268 (8)	0.0209 (8)	0.0132 (7)	0.0037 (6)	0.0043 (7)
C11	0.0222 (8)	0.0251 (8)	0.0252 (8)	0.0149 (7)	0.0009 (6)	0.0016 (7)
C5	0.0175 (8)	0.0230 (8)	0.0245 (8)	0.0095 (6)	−0.0029 (6)	0.0006 (6)
C7	0.0183 (8)	0.0338 (9)	0.0261 (8)	0.0111 (7)	−0.0005 (6)	−0.0021 (7)
C15	0.0307 (9)	0.0261 (9)	0.0234 (8)	0.0159 (7)	−0.0011 (7)	−0.0014 (7)
C13	0.0314 (9)	0.0392 (11)	0.0341 (9)	0.0243 (8)	−0.0009 (7)	0.0001 (8)
C14	0.0235 (8)	0.0337 (10)	0.0399 (10)	0.0143 (8)	0.0087 (8)	0.0077 (8)
C12	0.0292 (9)	0.0374 (10)	0.0334 (9)	0.0213 (8)	0.0007 (8)	−0.0069 (8)
C8	0.0281 (9)	0.0515 (12)	0.0347 (10)	0.0251 (9)	−0.0056 (8)	−0.0055 (9)
C10	0.0236 (9)	0.0389 (10)	0.0383 (10)	0.0128 (8)	−0.0078 (8)	−0.0103 (8)
C9	0.0214 (9)	0.0470 (12)	0.0398 (10)	0.0038 (8)	0.0029 (8)	0.0002 (9)

Geometric parameters (Å, º) top

O2—C15	1.447 (2)	C15—H15A	0.9900
O2—H1O2	0.91 (2)	C15—H15B	0.9900
C3—C4	1.396 (2)	C13—H13A	0.9800
C3—C2	1.404 (2)	C13—H13B	0.9800
C3—H3	0.9500	C13—H13C	0.9800
C4—C5	1.400 (2)	C14—H14A	0.9800
C4—C11	1.537 (2)	C14—H14B	0.9800
O1—C1	1.3820 (19)	C14—H14C	0.9800
O1—H1O1	0.84 (2)	C12—H12A	0.9800
C6—C5	1.389 (2)	C12—H12B	0.9800
C6—C1	1.405 (2)	C12—H12C	0.9800
C6—C15	1.509 (2)	C8—H8A	0.9800
C2—C1	1.405 (2)	C8—H8B	0.9800
C2—C7	1.544 (2)	C8—H8C	0.9800
C11—C12	1.536 (2)	C10—H10A	0.9800
C11—C13	1.536 (2)	C10—H10B	0.9800
C11—C14	1.536 (2)	C10—H10C	0.9800
C5—H5	0.9500	C9—H9A	0.9800
C7—C10	1.534 (2)	C9—H9B	0.9800
C7—C9	1.538 (2)	C9—H9C	0.9800
C7—C8	1.547 (2)

C15—O2—H1O2	103.7 (14)	H15A—C15—H15B	107.9
C4—C3—C2	123.95 (14)	C11—C13—H13A	109.5
C4—C3—H3	118.0	C11—C13—H13B	109.5
C2—C3—H3	118.0	H13A—C13—H13B	109.5
C3—C4—C5	117.04 (13)	C11—C13—H13C	109.5
C3—C4—C11	123.13 (13)	H13A—C13—H13C	109.5
C5—C4—C11	119.82 (13)	H13B—C13—H13C	109.5
C1—O1—H1O1	108.6 (16)	C11—C14—H14A	109.5
C5—C6—C1	119.30 (14)	C11—C14—H14B	109.5
C5—C6—C15	120.33 (14)	H14A—C14—H14B	109.5
C1—C6—C15	120.35 (14)	C11—C14—H14C	109.5
C3—C2—C1	116.49 (14)	H14A—C14—H14C	109.5
C3—C2—C7	121.49 (14)	H14B—C14—H14C	109.5
C1—C2—C7	122.02 (13)	C11—C12—H12A	109.5
O1—C1—C6	119.21 (13)	C11—C12—H12B	109.5
O1—C1—C2	119.35 (13)	H12A—C12—H12B	109.5
C6—C1—C2	121.44 (13)	C11—C12—H12C	109.5
C12—C11—C13	108.51 (13)	H12A—C12—H12C	109.5
C12—C11—C14	108.18 (14)	H12B—C12—H12C	109.5
C13—C11—C14	109.54 (13)	C7—C8—H8A	109.5
C12—C11—C4	111.91 (13)	C7—C8—H8B	109.5
C13—C11—C4	109.74 (13)	H8A—C8—H8B	109.5
C14—C11—C4	108.92 (13)	C7—C8—H8C	109.5
C6—C5—C4	121.72 (14)	H8A—C8—H8C	109.5
C6—C5—H5	119.1	H8B—C8—H8C	109.5
C4—C5—H5	119.1	C7—C10—H10A	109.5
C10—C7—C9	107.79 (14)	C7—C10—H10B	109.5
C10—C7—C2	112.17 (13)	H10A—C10—H10B	109.5
C9—C7—C2	109.65 (13)	C7—C10—H10C	109.5
C10—C7—C8	107.40 (14)	H10A—C10—H10C	109.5
C9—C7—C8	110.30 (15)	H10B—C10—H10C	109.5
C2—C7—C8	109.51 (14)	C7—C9—H9A	109.5
O2—C15—C6	111.99 (13)	C7—C9—H9B	109.5
O2—C15—H15A	109.2	H9A—C9—H9B	109.5
C6—C15—H15A	109.2	C7—C9—H9C	109.5
O2—C15—H15B	109.2	H9A—C9—H9C	109.5
C6—C15—H15B	109.2	H9B—C9—H9C	109.5

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H1O2···O2ⁱ	0.91 (2)	1.75 (2)	2.6636 (14)	178 (2)
O1—H1O1···O2	0.84 (2)	2.03 (2)	2.7706 (18)	146 (2)

Symmetry code: (i) −y+1, x−y, z+1/3.

Acknowledgements

We wish to acknowledge the use of the EPSRC-funded National Chemical Database Service hosted by the Royal Society of Chemistry, Manchester Metropolitan University for funding and Dr Paul Birkett for useful discussions.

References

Agilent (2014). CrysAlis PRO., Agilent Technologies, Yarnton, England. Google Scholar
Audouin, H., Bellini, R., Magna, L., Mézailles, N. & Olivier-Bourbigou, H. (2015). Eur. J. Inorg. Chem. 2015, 5272–5280. CSD CrossRef CAS Google Scholar
Barbour, L. J. (2001). J. Supramol. Chem. 1, 189–191. CrossRef CAS Google Scholar
Błocka, E., Jaworska, M., Kozakiewicz, A., Wełniak, M. & Wojtczak, A. (2010). Tetrahedron Asymmetry, 21, 571–577. Google Scholar
Campbell, I. S., Edler, K. L., Parrott, R. W., Hitchcock, S. R. & Ferrence, G. M. (2010). Acta Cryst. E66, o900–o901. Web of Science CSD CrossRef IUCr Journals Google Scholar
Esteves, C. V., Lima, L. M. P., Mateus, P., Delgado, R., Brandão, P. & Félix, V. (2013). Dalton Trans. 42, 6149–6160. CSD CrossRef CAS PubMed Google Scholar
Gagieva, S. C., Kolosov, N. A., Kurmaev, D. A., Fedyanin, I. V., Tuskaev, V. A. & Bulychev, B. M. (2014). Russ. Chem. Bull. 63, 2748–2750. CrossRef CAS Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CSD CrossRef IUCr Journals Google Scholar
Huang, Y., Tsai, Y.-H., Hung, W.-C., Lin, C.-S., Wang, W., Huang, J.-H., Dutta, S. & Lin, C.-C. (2010). Inorg. Chem. 49, 9416–9425. CSD CrossRef CAS PubMed Google Scholar
Huang, Y., Wang, W., Lin, C.-C., Blake, M. P., Clark, L., Schwarz, A. D. & Mountford, P. (2013). Dalton Trans. 42, 9313–9324. CSD CrossRef CAS PubMed Google Scholar
Kimura, S., Bill, E., Bothe, E., Weyhermüller, T. & Wieghardt, K. (2001). J. Am. Chem. Soc. 123, 6025–6039. CSD CrossRef PubMed CAS Google Scholar
Pujols-Ayala, I. & Barry, B. A. (2004). BBA-Energetics 1655, 205–216. CAS Google Scholar
Rogers, M. S. & Dooley, D. M. (2003). Curr. Opin. Chem. Biol. 7, 189–196. CrossRef PubMed CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sokolowski, A., Müller, J., Weyhermüller, T., Schnepf, R., Hildebrandt, P., Hildenbrand, K., Bothe, E. & Wieghardt, K. (1997). J. Am. Chem. Soc. 119, 8889–8900. CSD CrossRef CAS Web of Science Google Scholar
Solov'ev, M. V., Gagieva, S. C., Tuskaev, V. A., Bravaya, N. M., Gadalova, O. E., Khrustalev, V. N., Borissova, A. O. & Bulychev, B. M. (2011). Russ. Chem. Bull. 60, 2227–2235. CAS Google Scholar
Tuskaev, V. A., Gagieva, S. C., Solov'ev, M. V., Kurmaev, D. A., Kolosov, N. A., Fedyanin, I. V. & Bulychev, B. M. (2015). J. Organomet. Chem. 797, 159–164. CSD CrossRef CAS Google Scholar
Wang, X., Thevenon, A., Brosmer, J. L., Yu, I., Khan, S. I., Mehrkhodavandi, P. & Diaconescu, P. L. (2014). J. Am. Chem. Soc. 136, 11264–11267. CSD CrossRef CAS PubMed Google Scholar
Watkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, Oxford, England. Google Scholar
Zhu, S. R., Kou, F. P., Lin, H. K., Lin, C. C., Lin, M. R. & Chen, Y. T. (1996). Inorg. Chem. 35, 5851–5859. CSD CrossRef CAS Google Scholar