Crystal structure of 1,3-diphenyladamantane and trans-1,4-diphenylcyclohexane: Torsion angles about C-Ph bonds in α,ω-diphenyl(alicyclic hydrocarbon)

Article abstract of DOI:10.1016/S0022-2860(03)00348-X

The orientation of the two phenyl rings in α,ω-diphenylalkanes with rigid carbon skeletons is investigated through characterization of the crystal and molecular structures of 1,3-diphenyladamantane (1) and trans-1,4-diphenylcyclohexane (2). The two phenyl rings in 1 have different conformations about the C-Ph bonds, with torsion angles between the phenyl ring and the C1-C2-C3 plane of 0.65 and 71.7°. A hydrogen atom at the meta-position of one of the phenyl rings contact intermolecularly with a tertiary hydrogen atom at C5 of adamantane within the sum of van der Waals radii. Due to the helical conformation, the short CH?HC contacts (2.231 A?) construct supramolecular triple helical strands. In contrast to 1, the phenyl rings in 2 have identical configurations, with equatorial position and bisected conformation as expected from density functional calculations. The molecular packing of 2 exhibits a herringbone pattern of (aromatic)C-H?π contacts.

Full text of DOI:10.1016/S0022-2860(03)00348-X

Journal of Molecular Structure 655 (2003) 473–478
www.elsevier.com/locate/molstruc
Crystal structure of 1,3-diphenyladamantane
and trans-1,4-diphenylcyclohexane: torsion angles about
C–Ph bonds in a,v-diphenyl(alicyclic hydrocarbon)
*
Hideyuki Tukada , Katsura Mochizuki
Graduate School of Integrated Science, Yokohama City University, Seto22-2, Kanazawa-ku, Yokohama 236-0027, Japan
Received 19 March 2003; revised 17 May 2003; accepted 20 May 2003
Abstract
The orientation of the two phenyl rings in a,v-diphenylalkanes with rigid carbon skeletons is investigated through
characterization of the crystal and molecular structures of 1,3-diphenyladamantane (1) and trans-1,4-diphenylcyclohexane
(2). The two phenyl rings in 1 have different conformations about the C–Ph bonds, with torsion angles between the
phenyl ring and the C1–C2–C3 plane of 0.65 and 71.78. A hydrogen atom at the meta-position of one of the phenyl
rings contact intermolecularly with a tertiary hydrogen atom at C5 of adamantane within the sum of van der Waals radii.
˚
Due to the helical conformation, the short CH· · ·HC contacts (2.231 A) construct supramolecular triple helical strands. In
contrast to 1, the phenyl rings in 2 have identical configurations, with equatorial position and bisected conformation as
expected from density functional calculations. The molecular packing of 2 exhibits a herringbone pattern of (aromatic)C–
H· · ·p contacts.
q 2003 Elsevier B.V. All rights reserved.
Keywords: Diphenylcyclohexane; Diphenyladamantane; Triple helix; CH· · ·HC contact; Torsion angle
1. Introduction
dependent on the conformation of the terminal aryl
ring, the crystal structure of diphenylalkanes is
particularly interesting [5].
Alkanes with aryl rings at both ends are ubiquitous
in the investigation of electron transfer and various
types of electronic interactions between aryl rings
[1–4]. In these interactions, orbital interactions
through bonds and through space, one of the basic
concepts of orbital interactions, play an important
role. As these orbital interactions are highly
This report details the crystal structure of
1,3-diphenyladamantane 1 and trans-1,4-diphenyl-
cyclohexane 2 as representative diphenylalkanes,
with intervening tertiary alkyl groups and a three-
carbon chain length, and a secondary alkyl group and
four-carbon chain length, respectively. Although
these molecules have simple structures, the crystal
structures of 1 and 2 do not appear to have been
reported to date (Scheme 1).
*
Corresponding author. Tel./fax: þ81-45-787-2209.
E-mail address: htht@yokohama-cu.ac.jp (H. Tukada).
0022-2860/03/$ - see front matter q 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-2860(03)00348-X

474
H. Tukada, K. Mochizuki / Journal of Molecular Structure 655 (2003) 473–478
2.2. X-ray structure determination
A colorless crystal of 1 with dimensions
0.60 £ 0.30 £ 0.30 mm was mounted on a Mac
Science MXC3K diffractometer, and examined
under graphite monochromatized Mo Ka radiation
˚
(0.71073 A). Precise unit cell dimensions were
Scheme 1.
determined by least-squares refinement on the setting
angles of 2016 reflections ðu ¼ 2:14–27:498Þ: Data
reduction and corrections for absorption and
decomposition were carried out using the Mac
Science MXC software. Experimental conditions
and the resulting data are summarized in Table 1
[9]. The crystal structure was solved by direct
methods using Sir-92, part of maXus [10], and was
refined by the full-matrix least-squares method using
SHELXL 97 [11] with anisotropic parameters for all
non-hydrogen atoms. The positions of the hydrogen
atoms were placed according to SHELXL 97. The final
positional parameters for 1 are listed in Table 2 [9].
In a similar manner, the crystal structure of 2
(experimental conditions and crystal structure data
summarized in Table 1) was determined from 1373
2. Experimental
2.1. Preparation
According to the procedure of Chalais [6], 2 was
obtained from a suspension of FeCl3-doped mon-
tmorillonite K10 in benzene, and was purified by gel
permeation chromatography (GPC) to remove
1-phenyladamantane and a small amount of other
impurities. GPC was performed in this case with a
Shimadzu LC6AD/RID-6A/SPD-10A having a cir-
culating path through three Shodex-GPC columns,
using chloroform as the eluent. Data for 1: mp
1
106.5 8C; H NMR (270 MHz, in CDCl3) d 7:41 (dd,
J ¼ 7:2; 1.0 Hz, 4H), 7.33 (t, J ¼ 7:2 Hz; 4H), 7.19
(tt, J ¼ 7:2 1.0 Hz, 2H), 2.32 (hept, J ¼ 3:0 Hz; 2H),
2.05 (s, 2H), 1.96 (d, J ¼ 3:0 Hz; 8H), 1.79 (t, J ¼
3:0 Hz; 2H): 13C NMR (68 MHz, CDCl3) d 150:63;
128.21, 126.17, 125.73, 124.90, 48.96, 42.31, 37.28,
35.92, 29.59. Colorless crystals suitable for X-ray
structural analysis were grown by slow evaporation
Table 1
Crystallographic data for trans-1,4-diphenylcyclohexane (1) and
1,3-diphenyladamantane (2)
Compound
1
2
Formula
C22H24
288.40
C18 H20
236.40
Molecular weight
Crystal size (mm)
Color
of a hexane-ethanol (2:1) solution at room
temperature.
0.60 £ 0.30 £ 0.30 0.40 £ 0.30 £ 0.20
Colorless
298 (2)
Hexagonal
P31c
Colorless
298 (2)
Monoclinic
P21=n
7.069(2)
18.263(4)
5.618(2)
90.00
110.24(2)
90.00
680.5(3)
2
1.153
1,4-Diphenylcyclohexane was obtained from
4-phenylcyclohexanone in three steps: treatment
with phenylmagnesium bromide, dehydration using
conc. sulfuric acid in acetic acid, and hydrogenation
with palladium charcoal in ethyl acetate. The product
was a mixture of cis- and trans-diphenylcyclohexane
[7,8], and the trans-isomer was readily separated by
crystallization from an ethanol solution containing
both isomers. Data for 2 (trans): mp 173 8C; 1H NMR
(270 MHz, in CDCl3) d7:26 (m, 10H), 2.61 (t, J ¼ 9:5
Hz; 2H), 2.04 (d, J ¼ 7:3Hz; 4H), 1.64 (dd, J ¼ 9:5;
7.3 Hz, 4H); 13C NMR (68 MHz, CDCl3) d 147:42;
128.34, 126.83, 125.96, 44.06, 34.54. Crystals
suitable for X-ray structural analysis were grown by
slow evaporation of an ethanol solution at room
temperature.
Temperature (K)
Crystal system
Space group
˚
a (A)
18.995(5)
18.995(5)
7.835(4)
90.00
˚
b (A)
˚
c(A)
a(deg)
b (deg)
g(deg)
90.00
120.00
2448(2)
6
1.174
0.066
3
˚
Volume (A )
Z
D calc (g cm3)
m(mm21
Absorption correction
)
0.065
Via c scan
936
Via c scan
256
1373
Fð000Þ
Independent reflections 2016
Goodness-of-fit on F2
Final R indices
½I . 2sðIÞꢀ R1
wR2
1.062
0.0579
1.144
0.0638
0.1134
0.1455

H. Tukada, K. Mochizuki / Journal of Molecular Structure 655 (2003) 473–478
475
Table 2
Selected bond lengths, bond angles, atomic coordinates and
equivalent isotropic displacement parameters for 1
x
y
z
UðeqÞ
C(1)
C(2)
C(11)
C(3)
C(4)
C(17)
C(10)
C(16)
C(7)
4478(2)
3770(3)
4665(2)
3590(2)
4373(3)
2890(3)
4123(3)
5310(3)
4269(3)
5232(3)
5051(3)
4227(3)
5499(3)
4883(3)
3405(3)
5073(3)
4416(3)
2998(3)
2374(5)
2132(3)
1634(5)
1500(4)
2204(2)
1667(2)
1718(3)
2159(2)
2687(3)
1588(3)
3299(3)
2119(3)
2782(3)
2715(3)
873(3)
5040
3861(8)
6335(8)
2553(7)
1490(7)
1386(8)
4695(8)
7472(8)
5990(7)
3909(8)
8758(9)
6468(8)
8663(8)
3621(9)
3550(8)
2667(8)
7645(9)
179(9)
42(1)
46(1)
46(1)
45(1)
55(1)
53(1)
60(1)
62(1)
51(1)
54(1)
72(2)
57(1)
71(2)
67(1)
56(1)
58(1)
68(1)
72(1)
96(2)
72(2)
103(2)
97(2)
C(6)
Fig. 1. ORTEP diagram [19] of 1 with labels. Non-H atoms are
represented by thermal ellipsoids with 50% probability levels.
C(14)
C(12)
C(15)
C(9)
C(8)
C(5)
C(13)
C(18)
C(19)
C(22)
C(20)
C(21)
877(3)
1704(4)
3803(3)
2743(3)
3233(3)
460(3)
1118(3)
580(4)
1501(3)
510(4)
957(4)
ation were performed using an MM3 parameter set for
molecular mechanics calculations in CAChe [13].
2869(11)
1493(8)
2732(10)
440(11)
3. Results and discussion
The molecular structures of 1 and 2 are shown in
Figs. 1 and 2. Crystals of 1 are hexagonal with space
UðeqÞ is defined as one third of the trace of the orthogonalized
Uij tensor.
independent reflections ðu ¼ 2:23–27:508Þ; and final
structural positions and anisotropic parameters are as
shown in Table 3.
2.3. Density functional theory and molecular
mechanics calculations
Fig. 2. ORTEP diagram of 2 with labels. Non-H atoms are
represented by thermal ellipsoids with 50% probability levels. Atom
numbered with underbars are generated by symmetry transform-
ations, and are shown with # in Table 5
The gas-phase geometries of 1 and 2 were fully
optimized using the B3LYP hybrid density functional
and the 6-31G* basis set of the GAUSSIAN 98 program
package (rev. A.7) [12]. Estimation of barriers on
rotation about C–Ph bonds and structural optimiz-
Table 4
Atomic coordinates ( £ 104) and equivalent isotropic displacement
2
3
˚
parameters (A £ 10 ) for 2
Table 3
˚
Selected bond lengths (A) and angles (deg) for 1
x
y
z
UðeqÞ
C(3)
C(4)
C(5)
C(2)
C(1)
C(9)
C(7)
C(8)
C(6)
3766(3)
1960(3)
1692(3)
3178(3)
5014(3)
512(3)
21363(3)
21132(3)
56(4)
604(1)
1109(1)
1581(1)
2199(1)
2701(1)
1116(1)
2047(1)
1584(1)
2045(1)
3445(4)
2541(4)
520(4)
2886(4)
3751(4)
3704(4)
855(5)
41(1)
40(1)
48(1)
51(1)
52(1)
48(1)
54(1)
53(1)
56(1)
C(1)–C(2)
C(1)–C(7)
C(2)–C(3)
C(11)–C(16)
C(3)–C(8)
C(4)–C(5)
C(17)–C(18)
C(2)–C(1)–C(11)
C(11)–C(1)–C(7)
C(11)–C(1)–C(6)
C(1)–C(2)–C(3)
1.526(5)
1.534(5)
1.536(5)
1.393(6)
1.535(6)
1.522(6)
1.384(7)
113.1(3)
109.4(3)
109.7(3)
112.8(3)
C(1)–C(11)
C(1)–C(6)
C(11)–C(12)
C(3)–C(17)
C(3)–C(4)
C(17)–C(22)
C(10)–C(9)
C(2)–C(1)–C(7)
C(2)–C(1)–C(6)
C(7)–C(1)–C(6)
C(12)–C(11)–C(1)
1.528(5)
1.546(6)
1.387(6)
1.530(6)
1.555(5)
1.368(6)
1.525(7)
108.4(3)
107.6(4)
108.6(3)
123.9(4)
2869(5)
2309(4)
UðeqÞ is defined as one third of the trace of the orthogonalized
Uij tensor.

476
H. Tukada, K. Mochizuki / Journal of Molecular Structure 655 (2003) 473–478
ꢀ 3
Table 5
˚
Selected bond lengths (A) and angles (deg) for 2
group P31c; Z ¼ 6; V ¼ 2448ð2Þ A : Dimensions and
other crystal data are listed in Table 1. For 2, crystals
are monoclinic with space group P21=c; Z ¼ 2; V ¼
C(3)–C(4)
1.513(2) C(3)–C(1)#1
1.526(3) C(3)–H(3)
1.385(3) C(4)–C(9)
1.379(3) C(5)–H(5)
1.524(3) C(2)–H(2A)
1.522(3)
0.9880
1.392(3)
0.9300
0.9700
ꢀ 3
680:5ð3Þ A ; and possess the characteristics shown in
C(3)–C(2)
C(4)–C(5)
Table 1. Selected bond lengths and angles for 1 and 2
are summarized in Tables 4 and 5.
C(5)–C(6)
C(2)–C(1)
There are two distinct conformations about the
C–Ph bond in 1. The torsion angle between the
phenyl ring (A) at C1 and the plane of C3–C2–C1
(indicated by solid lines in the molecular schema) is
0.658 (eclipsed to C1–C2). The torsion angle on the
other side of the phenyl ring (B) at C3 is 71.78
C(2)–H(2B)
C(4)–C(3)–C(2)
0.9700
C(4)–C(3)–C(1)#1 112.7(2)
112.2(2) C(4)–C(3)–H(3)
107.2
119.3
109.3
C(1)#1–C(3)–C(2) 109.9(2) C(6)–C(5)–H(5)
C(1)–C(2)–C(3) 111.7(2) C(1)–C(2)–H(2A)
Symmetry transformations used to generate equivalent atoms:
#1 2x þ 1; 2y; 2z þ 1:
Fig. 3. (a) Crystal packing of 1 projected onto ab plane. Dashed lines indicate intermolecular short CH· · ·HC contacts. (b) Perspective view of
supramolecular triple helix.

H. Tukada, K. Mochizuki / Journal of Molecular Structure 655 (2003) 473–478
477
(eclipsed to C3–C8). The planes of the two phenyl
rings cross at 738.
and the electronic character of the substituents was
recognized. Among this data, 2 had the smallest f:
The supramolecular profiles of 1 and 2 are also
interesting. For 1, an aromatic hydrogen at a meta-
position of the phenyl ring with smaller torsion angle
contacts intermolecularly with a tertiary hydrogen
atom at C5 of the adamantane skeleton within the
˚
sum of van der Waals radii (2.4 A) [15]. Due to
the unsymmetrical conformation, the short CH· · ·HC
˚
contacts (2.231 A) construct supramolecular strands
forming a triple helix. Bisecting the cell in the plane
Based on the MM3 calculations for 1, the four
possible eclipsed conformers have almost the same
energy. The conformer with torsion angles of
þ58.3/ þ 60.88 (under the definition of two C–Ph
torsion angles as mentioned earlier) is within
0.01 kJ mol21 of the conformer with 0.6/0.28, and
both are only 0.07 and 0.38 kJ mol21 below the
structures of 0.6/61.28 and 261.0/61.78, respectively.
The calculated barrier (MM3) on rotation around
Ph–C in 1 is as low as ca. 3.9 kJ mol21 (interconver-
sion between rotamers described earlier). Thus, the
crystal structure of 1 adopts one of the stable rotamers
given by MM3 calculations. The small deviation of
about 108 between the crystal and the calculated
structures is attributable to molecular packing in
crystals. As the present authors recently discussed in
relation to the structure of diphenylmethanes [5],
torsion angles in crystals often differ from those of
optimized calculated structures.
¯
(1,1,0), the two sets of triple helices coil in opposite
Although no data is available in the Cambridge
structural database (CSD) for 1,3-di( p-monosubsti-
tuted phenyl)adamantanes [14], two reports for
1,3,5,7-tetrakis( p-monosubstituted phenyl)adaman-
tanes (CSD ref-code, HAZQOO, QOTXUS) are
known. In these cases, four aryl groups are eclipsed
to C–C bonds in different directions, which is
consistent with the present result.
In crystals, trans-1,4-diphenylcyclohexane 2, a
a,v-diphenyl(alicyclic hydrocarbon) in which the
intervening hydrocarbon unit is secondary, has a
bisected conformation about the C–Ph bonds at the
1- and 4-positions in cyclohexanes (both labeled C3 in
Fig. 2), and the torsion angles HC–Ph ðfÞ of both are
identical ðf ¼ 6:498Þ: The conformation is the same
as the structure optimized by density functional
calculation (f ¼ 0:48 in gas phase). Thus, the two
phenyl rings in 2 stand parallel (co-facial), facilitating
p–s–p orbital interaction between terminal aryl
moieties.
A total of eight crystallographic data entries were
found in the CSD for trans-1-substituted-4-(4-mono-
substituted phenyl)cyclohexanes. The substituents are
not expected to affect the conformation of the phenyl
ring. The f angles in these entries fell between 8.0
and 33.68, and no correlation between the f angles
Fig. 4. Crystal packing of 2 projected onto bc plane. Thermal
ellipsoids are shown with 30% probability levels.

478
H. Tukada, K. Mochizuki / Journal of Molecular Structure 655 (2003) 473–478
[6] S. Chalais, A. Cornelis, A. Gerstmans, W. Kolodziejski, P.
Laszlo, A. Mathy, P. Metra, Helv. Chim. Acta. 68 (1985)
1196–1203.
directions (Fig. 3). This helix motif is of interest in
terms of the supramolecular architecture of crystals,
and has been recognized in a number of studies
[16–18].
[7] H. Pines, W.F. Fry, N.C. Sih, C.T. Goetschel, J. Org. Chem. 31
(1966) 4094.
CH· · ·p interaction is dominant in 2, although the
contact is not within the sum of van der Waals radii.
This results in a herringbone pattern along the b axis,
as shown in Fig. 4. The herringbone pattern is
ubiquitous in the crystal structure of non-polar and
flat aromatic hydrocarbons.
[8] S.G. Levine, A.S. Ng, J. Org. Chem. 50 (1985) 390.
[9] CSD deposition numbers: 1, CCDC174574(ICOKUG); 2,
CCDC 174575 (ICOKOA)
[10] maXus (v.4.3) software by C. Gilmore, University of
Glasgow. Sir 92 A. Altomare, G. Cascarano, C. Giacovazzo,
A. Guagliardi, M.C. Burla, G. Polidori, M. Camalli, J. Appl.
Cryst. 27 (1974) 435.
The findings of this study will contribute to the
understanding of conformations about C–Ph bonds in
a,v-diphenylalkanes, and to the design of molecular
packing using non-polar phenyl-substituted alicyclic
hydrocarbons.
[11] G.M. Sheldrick, SHELXL 97. Program for the Refinement of
Crystal Structures, University of Gottingen, Germany, 1999
[12] GAUSSIAN 98 revision A7, Gaussian, Inc., USA.
[13] CAChe v4.4. Oxford Molecular Ltd. and Fujitsu Ltd. A MM3
program produced by Allinger:N.L. Allinger, Y.H. Yuh, J.-H.
Lii, J. Am. Chem. Soc. 111 (1989) 8551.
[14] Cambridge Crystallographic Data Centre, CSD (v. 5.24);
ConQuest (v.1.5), Nov. 2002.
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