2-[(trifluoroacetyl)amino]benzoquinone and the hydrochloride and perchlorate salts of 2-aminohydroquinone

Article abstract of DOI:10.1023/B:JOCC.0000014695.55435.5e

Hydrogen bonding parameters for the title materials are reported. 2-[(trifluoroacetyl)amino]benzoquinone crystallizes in the monoclinic space group P2₁/c, with a = 18.195(4), b = 5.110(1), c = 9.635(2), β = 104.22(3)°, V = 868.4(3) A³, and Z = 4. This compound exhibits two weak intramolecular hydrogen bonds. The first is between a hydrogen atom of the quinone ring and the carbonyl oxygen of the trifluoroacetamide group; it has a distance of 2.24 A and a C-H ... O angle of 122°. The second is between the hydrogen atom of the trifluoroacetamide group and a quinone carbonyl group; it has a distance of 2.26 A and a N-H ... O angle of 107°. 2-Aminohydroquinone hydrochloride crystallizes in the orthorhombic space group Pca2₁, with a = 16.220(3), b = 5.211(1), c = 8.719(2), V = 737.0(2) A³, and Z = 4. 2-Aminohydroquinone perchlorate crystallizes in the orthorhombic space group P2₁2 ₁2₁, with a = 7.110(1), b = 7.139(1), c= 18.043(4), V = 915.8(3) A³, and Z = 4. All active hydrogens of the two salts exhibit intermolecular hydrogen bonds that serve to organize a three-dimensional framework for each case.

Full text of DOI:10.1023/B:JOCC.0000014695.55435.5e

Journal of Chemical Crystallography, Vol. 34, No. 2, February 2004 (�
2004)
C
2
-[(trifluoroacetyl)amino]benzoquinone
and the hydrochloride and perchlorate salts
of 2-aminohydroquinone
(1)�
(1)
(1)
(1)
David Wiedenfeld, Mark Minton, Vladimir Nesterov, and Christine Montoya
Received June 1, 2003
Hydrogen bonding parameters for the title materials are reported. 2-
(trifluoroacetyl)amino]benzoquinone crystallizes in the monoclinic space group
[
�
˚ 3
P21/c, with a = 18.195(4), b = 5.110(1), c = 9.635(2), � = 104.22(3) , V = 868.4(3) A ,
and Z = 4. This compound exhibits two weak intramolecular hydrogen bonds. The
first is between a hydrogen atom of the quinone ring and the carbonyl oxygen of
˚
the trifluoroacetamide group; it has a distance of 2.24 A and a C H ���O angle of
�
1
22 . The second is between the hydrogen atom of the trifluoroacetamide group and
˚
�
a quinone carbonyl group; it has a distance of 2.26 A and a N H ���O angle of 107 .
2
-Aminohydroquinone hydrochloride crystallizes in the orthorhombic space group
˚
3
Pca21, with a = 16.220(3), b = 5.211(1), c = 8.719(2), V = 737.0(2) A , and Z = 4.
2
-Aminohydroquinone perchlorate crystallizes in the orthorhombic space group P212121,
˚
3
with a = 7.110(1), b = 7.139(1), c = 18.043(4), V = 915.8(3) A , and Z = 4. All active
hydrogens of the two salts exhibit intermolecular hydrogen bonds that serve to organize a
three-dimensional framework for each case.
KEY WORDS: Crystal structure; intermolecular hydrogen bonds; 2-[(trifluoroacetyl)amino]benzoquinone;
2
-aminohydroquinone.
Introduction
as well as substituted quinones (additional sub-
stituents could be halogen, methyl, nitrile, etc.).
In the course of this work, we have prepared
2-[(trifluoroacetyl)amino]benzoquinone 1 by the
We are engaged in the synthesis of
donor/acceptor molecules for electron-transfer
studies that will feature ammonium quinone ac-
ceptors; our initial focus was on preparing ma-
terials in which the ammonium moiety is di-
rectly attached to the quinone skeleton. We
sought materials that had no substituents (par-
ent quinone) other than the ammonium group
1
method of Aulinger, Arnold, and Steglich.
Deprotection of the intermediate hydroquinone
by dry methanolic hydrogen chloride afforded
2-aminohydroquinone hydrochloride 2. Finally,
metathesis of the chloride anion to the perchlo-
rate salt 3 was accomplished with silver perchlo-
rate (Note: caution should be used when handling
this perchlorate salt since it is potentially shock
sensitive). The chloride salt 2 is known as a par-
(
1)
Department of Natural Sciences – Chemistry, New Mexico High-
lands University, Las Vegas, New Mexico 87701.
To whom correspondence should be addressed; e-mail:
dwiedenfeld@nmhu.edu.
2
�
tially deuterated material, while perchlorate 3 is
previously unreported.
95
1
074-1542/04/0200-0095/0 �C 2004 Plenum Publishing Corporation

9
6
Wiedenfeld, Minton, Nesterov, and Montoya
group and a hydrogen of the quinone ring, is less
typical; nonbonded contacts of this type are con-
sidered to be weak hydrogen bonds since the pro-
ton donor involves a hydrogen–carbon bond.5
Experimental section
General
˚
Methanol was dried over 3 A molecular
sieves. Melting points were determined on a Mel-
Temp II apparatus and are uncorrected. NMR
spectra were obtained with a Bruker AC-300 spec-
trometer. Tetramethylsilane was used as reference
for proton spectra in CDCl and DMSO-d , while
3
6
for pyridine-d the residual proton absorption at
5
�
8.71 was used. For carbon spectra the CDCl3
absorption at � 77.0, the DMSO-d absorption at
6
We now report solid-state intramolecular hy-
drogen bonding in compound 1 as well as the
structures of the salts 2 and 3. Trifluoroacetamide
�
39.5, or the pyridine-d absorption at � 149.9
5
were used as references. Assignments were made
with the aid of coupled spectra and SFORD.
1
features two solid-state intramolecular hydro-
2-[(trifluoroacetyl)amino]hydroquinone
gen bonds: the first is a hydrogen bond between
the carbonyl oxygen of the acetamide group and a
hydrogen of the quinone ring, while the second is
between the N H of the acetamide and one of the
quinone carbonyl oxygens. Salts 2 and 3 exhibit
hydrogen bonds between active hydrogens and the
relevant counterions.
was prepared according to Aulinger, Arnold, and
Steglich.1
2-[(trifluoroacetyl)amino]-1,4-benzoquinone
1
was isolated from oxidation of the above
hydroquinone using iodosobenzene diacetate as
reported by Aulinger, Arnold, and Steglich.1
However, in our hands concomitant deprotection
of the amino group did not occur. The red-orange
Hydrogen bonds play a central role in the
chemistry of biological systems and can markedly
crystalline product gave the following spectra:
3
,4
influence conformation. The intramolecular hy-
drogen bonding subset occurs when a proton
donor is oriented properly to interact with a prox-
imal acceptor species. The most common accep-
torsarehardelectron-richspeciessuchascarbonyl
oxygens, ether or alcohol oxygens, and amine ni-
trogens. Systemsinwhichtheatomsthatbehaveas
the proton donor and the acceptor are both highly
electronegative can have different hydrogen-bond
strengths depending on the distance involved.5
The hydrogen bond in 1 between the N H of the
acetamide and a quinone oxygen can be classified
as a weak hydrogen bond, since the distance in-
1
H NMR (CDCl , �): 8.77 (1H, br, NH), 7.62
3
(
1H, d, J = 2.2 Hz, H-3), 6.91 (1H, d, J = 9.9
Hz, H-6), 6.84 (1H, dd, J = 9.9, 2.2 Hz, H-5).
1
3
C NMR (CDCl , �): 186.8 (C-4), 181.2 (C-1),
3
1
1
55.5 (q, JCF = 39.2 Hz, COCF ), 138.3 (C-5),
3
36.5 (C-2), 133.4 (C-6), 117.6 (C-3), 114.7 (q,
JC F = 288.3 Hz, COCF3).
2-Aminohydroquinone hydrochloride 2
Acetyl chloride (5 mL) was added rapidly
dropwise to 50 mL of dry methanol cooled in ice
and stirred under nitrogen. After 30 min 1.0 g
˚
volved is 2.26 A. The second hydrogen bond in 1,
1
thatbetweenthecarbonyloxygenoftheacetamide
(4.5 mmol) of the hydroquinone of 1 was added

2
-[(trifluoroacetyl)amino]benzoquinone
97
and stirring was continued for 2 days at room
temperature. Volatiles were removed on the rotary
evaporator followed by high-vacuum drying.
The resulting pale yellow-green crystalline solid
was recrystallized from absolute ethanol giving
able light yellow crystals of 1 and light grey
crystals of 2 and 3 with approximate dimen-
sions 0.55 � 0.45 � 0.20, 0.30 � 0.20 � 0.10, and
0.30 � 0.25 � 0.20 mm were found. Diffrac-
�
tion data for 1–3 were collected at 25 C
�
dark green plates, mp 219–221 C with decom-
on an Enraf-Nonius CAD4 diffractometer with
1
position. H NMR (DMSO-d , �): 9.89 (4H, br,
graphite-monochromatized Mo K� radiation (� =
6
˚
OH + NH ), 9.28 (1H, br, OH), 6.85 (1H, d,
0.71073 A). Three standard reflections measured
3
J = 8.5 Hz, H-6), 6.84 (1H, d, J = 2.9 Hz, H-3),
after every 97 reflections showed decay for 1 dur-
ing the experiment, but there was no decay ob-
served for 2 and 3. For intensities and background,
the individual reflection profiles were analyzed.
The structures were solved by direct methods.
It was found that the fluorine atoms of the tri-
fluoromethyl group in 1 are disordered and oc-
cupy two different positions with a ratio of 2:1,
1
6
(
7
.63 (1H, dd, J = 8.8, 2.9 Hz, H-5). H NMR
pyridine-d , �): 9.86 (5 H, br, OH + NH ),
5
2� 3
.14 (1H, d, J = 2.9 Hz, H-3), 7.12 (1H, d,
J = 8.8 Hz, H-6), 6.63 (1H, dd, J = 8.5, 2.9 Hz,
1
3
H-5). C NMR (DMSO-d , �): 150.0 (C-4),
6
1
(
43.0 (C-1), 118.9 (C-2), 116.9 (C-6), 115.6
C-5), 110.9 (C-3). 13C NMR (pyridine-d , �):
5
6
152.8 (C-4), 140.4 (C-1), 135.1 (C-2), 117.1
which is a usual case for such a group. Refine-
(
C-6), 107.5 (C-5), 106.2 (C-3). For a similar
ment was done by full-matrix least-squares first
isotropically and then anisotropically for all non-
H atoms using SHELXTL97. Hydrogen atoms in
preparation of partially deuterated material see
Gould, Shen, and Whittle.2
7
all structures were placed in geometrically calcu-
lated positions and introduced in the refinements
using the riding approximation. The final differ-
ence map showed no unusual features, with no
significant peaks above the general background.
Crystal and structure determination data for 1–3
are summarized in Table 1.
2
-Aminohydroquinone perchlorate 3
A solution of 0.13 g (0.62 mmol) of silver
perchlorate in 4 mL of dry methanol was added
rapidly dropwise to a stirred solution of 0.10 g
(0.62 mmol) of the hydrochloride 2 in 4 mL of
methanol. A precipitate formed immediately. The
suspension was stirred for 30 min under nitro-
gen, during which time the color lightened. The
precipitated silver chloride was filtered off and
washed with a little methanol. The combined fil-
trate and washings were rotary evaporated and
high-vacuum dried leaving a quantitative yield
of green crystalline perchlorate. Recrystallization
�
from absolute ethanol gave mp 160-162 C with
decomposition. NMR data very similar to the hy-
drochloride. Similar reactions were used to pre-
pare the tetrafluoroborate and tosylate salts from
the chloride.
Fig. 1. General view of molecule 1. Fluorine atoms are disor-
dered and occupy two different positions. The non-H atoms
are shown with thermal ellipsoids drawn at the 30% proba-
Crystallography
7
Single crystals of 1–3 were obtained by
bility level. H atoms are drawn as circles of arbitrary small
slow evaporation of their ethanol solutions. Suit-
radius for clarity.

9
8
Wiedenfeld, Minton, Nesterov, and Montoya
Table 1. Structure Determination Summary for 1–3
1
2
3
CCDC deposit no. 210968
210969
210970
Empirical formula C8H4F3NO3 C6H8ClNO2 C6H8ClNO6
Formula weight
Diffractometer
Temperature, K
Crystal system
Space group; Z
219.12
Enraf-Nonius Enraf-Nonius Enraf-Nonius
298 298 298
Monoclinic Orthorhombic Orthorhombic
161.58
225.58
P21/c; 4
18.195(4)
5.110(1)
9.635(2)
90.00
Pca21; 4
16.220(3)
5.211(1)
8.719(2)
90.00
P212121; 4
7.110(1)
7.139(1)
18.043(4)
90.00
˚
a, A
˚
b, A
˚
c, A
�
�,
�
�
�
�
,
,
104.22(3)
90.00
90.00
90.00
90.00
90.00
Volume, A3
Density (g/cm 3)
scan range
Absorbtion coeff.
˚
868.4(3)
1.676
2–26
737.0(2)
1.456
3–28
915.8(3)
1.636
2–28
�
�
0.170
0.450
0.42
�
1
(mm
)
Indep. refls.
Obs. refls.
Final R1
Final wR2
Goodness of fit
1661
932
0.0965
0.2195
1.029
930
399
0.0766
0.1645
1.024
2185
847
0.0780
0.1605
0.944
Fig. 2. General view of salt 2. Cation and anion are linked
by H-bond O H ���Cl. The non-H atoms are shown with
7
thermal ellipsoids drawn at the 30% probability level. H
atoms are drawn as circles of arbitrary small radius for clarity.
hedral angle between the flat ring and the similarly
flat portion of the trifluoroacetamide fragment is
equal to 2.5 . The formation of an intramolecular
Results and discussion
�
General views of the investigated molecules
are shown in Figs. 1–3. Selected bond lengths for
compounds 1–3 are listed in Table 2.
non-bonded contact between the oxygen atom of
With the exception of the fluorine atoms,
molecule 1 has an almost planar structure: the di-
Table 2. Selected Bond Distances in the Molecule
1
and Cations 2 and 3
Bond
1
2
3
O(1) C(1)
O(2) C(4)
O(3) C(7)
N(1) C(2)
N1 C(7)
1.212(4) 1.35(1) 1.341(9)
1.227(5) 1.37(1) 1.387(8)
1.202(6)
1.391(5) 1.45(2) 1.458(7)
1.361(5)
—
—
—
—
C(1) C(2)
C(2) C(3)
C(3) C(4)
C(4) C(5)
C(5) C(6)
C(6) C(1)
C(7) C(8)
1.484(5) 1.40(2) 1.380(9)
1.329(5) 1.38(2) 1.375(9)
1.456(5) 1.37(1) 1.351(9)
1.463(6) 1.39(2) 1.369(9)
1.317(5) 1.38(2) 1.383(9)
1.470(5) 1.36(2) 1.36(1)
Fig. 3. General view of salt 3. A fork H-bond links the cation
and anion to each other. The non-H atoms are shown with
7
thermal ellipsoids drawn at the 30% probability level. H
1.501(7)
—
—
atoms are drawn as circles of arbitrary small radius for clarity.

2
-[(trifluoroacetyl)amino]benzoquinone
99
Fig. 4. A projection onto the ac plane showing the H-bonding scheme of salt 2.
the carbonyl group of the acetamide group and the
H3A atom of the quinone ring contributes to this
arrangement. According to literature data describ-
parameters for this contact in compound 1 are:
˚
˚
C3 H3A 0.93 A, H3A ���O3 2.24 A, C3 ���O3
�
˚
2.843(6) A, angle C3 H3A ���O3 122 . Thus we
assign this contact to be a weak intramolecular
hydrogen bond rather than a classical van der
Waals contact. That a six-membered ring forms
likely facilitates hydrogen bond formation and the
5
ing C H—O contacts, a C—O distance of less
˚
than 3.25 A is a conservative threshold for dis-
tinguishing weak hydrogen bond contacts from
classical van der Waals contacts. In our case, the
Fig. 5. A projection onto the ab plane showing the H-bonding scheme of salt 3.

1
00
Wiedenfeld, Minton, Nesterov, and Montoya
Table 3. Hydrogen-Bond Parameters for 2
6
D
H
d(D H) d(H ���A)
DHA d(D ���A)
A
O1 H1A
O2 H2A
N1 H1B
N1 H1C
N1 H1D
0.82
0.82
0.89
0.89
0.89
1.95
2.33
2.28
2.28
2.28
154
148
173
168
168
2.711
3.059
3.170
3.200
3.143
O2 [� x + 1/2, y + 1, z � 1/2]
Cl1 [x, y, z]
Cl1 [x � 1/2, � y, z]
Cl1 [� x + 1/2, y, z � 1/2]
Cl1 [x � 1/2, � y + 1, z]
Table 4. Hydrogen-Bond Parameters for 3
6
D
H
d(D H) d(H ���A)
DHA d(D ���A)
A
O1 H1A
O2 H2A
N1 H1B
N1 H1B
N1 H1C
N1 H1C
N1 H1D
N1 H1D
0.82
0.82
0.89
0.89
0.89
0.89
0.89
0.89
1.87
1.95
2.14
2.47
2.28
2.34
2.10
2.52
175
160
154
121
137
125
147
146
2.689
2.734
2.968
3.033
2.987
2.938
2.885
3.294
O2 [x, y + 1, z]
O4 [x � 1/2, � y � 1/2, � z]
O5[� x + 1, y � 1/2, � z + 1/2]
O3 [x � 1, y, z]
O5 [x � 1, y, z]
O3 [� x + 1, y + 1/2, � z + 1/2]
O4 [x, y, z]
O6 [x, y, z]
resulting arrangement leads to flattening of the
molecule.
Acknowledgment
We thank the NIH (D.W., Grant S06
It should also be noted that hydrogen atom
H1A of compound 1, which is bonded to N1,
forms a short intramolecular contact with O1 of
GM008066-31) for generous financial support.
˚
the quinone ring with a distance of 2.26 A. This
is less than the sum of the van der Waals radii
Supplementary material
8
˚
of these atoms. The N1—O1 distance is 2.64 A
�
and the N1 H1A—O1 angle is 107 . This hydro-
CCDC-210968-210970 contains the sup-
plementary crystallographic data for this pa-
per. These data can be obtained free of charge
at www.ccdc.cam.ac.uk/conts/retrieving.html or
from the Cambridge Crystallographic Data Cen-
tre (CCDC), 12 Union Road, Cambridge CB2
1EZ, United Kingdom; fax: +44(0)1223-336033;
e-mail: deposit@ccdc.cam.ac.uk.
gen bond creates a five-membered ring and also
helps to flatten this portion of the molecule. The
hydrogen bond parameters are consistent with a
related N H—O intramolecular hydrogen bond
9
that we have recently described.
In salts 2 and 3, all active hydrogen atoms
participate in hydrogen bond formation and link
cations and anions into three-dimensional frame-
works (Tables 3 and 4 and Figs. 4 and 5). We
observed the following types of hydrogen bonds
in these salts (refer to the figures for the exact
structural elements involved): O H—O, O H—
Cl, N H—Cl, and N H—O. Most of these hy-
drogen bonds can be considered to be weak. The
remaining geometrical parameters in the investi-
gated molecules have standard values.10
References
1. Aulinger, K.; Arnold, N.; Steglich, W.Z. Naturforsch. C 2000,
55, 481.
2
. Gould, S.J.; Shen, B.; Whittle, Y.G. J. Am. Chem.
Soc. 1989, 111, 7932; Matsuoka, M.; Yamakawa, K.
Chem. Abstr. 2001, 135, P288574s JP 2001 278,845.
Kricheldorf, H.R.; Thomsen, S.A. Makromol. Chem. 1993, 194,
2063.

2
-[(trifluoroacetyl)amino]benzoquinone
101
3
4
. Aaron, H.S. Top. Stereochem. 1980, 11, 1.
. Emsley, J. Structure and Bonding; Springer-Verlag: Berlin,
7. Sheldrick, G.M. SHELXTL-97 V5.10; Bruker AXS: Madison,
WI, 1997.
1
984.
8. Rowland, R.S.; Taylor, R. J. Phys. Chem. 1996, 100, 7384.
9. Nesterov, V.N.; Viltchinskaia, E.A.; Nesterova, S.V. Acta Crys-
tallogr. 2003, E59, o625.
5
. Desiraju, G.R.; Steiner, T. The Weak Hydrogen Bond; Oxford
University Press: Oxford, 1999.
6
. Kislyi, V.P.; Nesterov, V.N.; Semenov, V.V. Russ. Chem. Bull.
10. Allen, F.H.; Kennard, O.; Watson, D.G.; Brammer, L.; Orpen,
A.G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1.
1
997, 6, 1150.