A simple and clean procedure for the synthesis of polyhydroacridine and quinoline derivatives: Reaction of Schiff base with 1,3-dicarbonyl compounds in aqueous medium

Article abstract of DOI:10.1016/j.tetlet.2005.08.091

A clean and simple synthesis of benzo[c]acridine, benzo[a]acridine, pyrido[2,3-c]acridine and benzo[f]quinoline derivatives was accomplished in good to excellent yields via the reaction of Schiff base with 1,3-dicarbonyl compounds in aqueous medium catalyzed by TEBA. The structures were characterized by ¹H NMR, IR and elemental analysis, and confirmed by X-ray diffraction study.

Full text of DOI:10.1016/j.tetlet.2005.08.091

Tetrahedron
Letters
Tetrahedron Letters 46 (2005) 7169–7173
A simple and clean procedure for the synthesis of
polyhydroacridine and quinoline derivatives: reaction of Schiff
base with 1,3-dicarbonyl compounds in aqueous medium
a
a
a,c
Xiang-Shan Wang,a,b,c, Mei-Mei Zhang, Zhao-Sen Zeng, Da-Qing Shi,
*
Shu-Jiang Tu,a,c Xian-Yong Weib and Zhi-Min Zongb
aDepartment of Chemistry, Xuzhou Normal University, Xuzhou Jiangsu 221116, China
bSchool of Chemical Engineering, China University of Mining and Technology, Xuzhou Jiangsu 221008, China
cThe Key Laboratory of Biotechnology on Medical Plant of Jiangsu Province, Xuzhou 221116, China
Received 6 June 2005; revised 18 August 2005; accepted 18 August 2005
Abstract—A clean and simple synthesis of benzo[c]acridine, benzo[a]acridine, pyrido[2,3-c]acridine and benzo[f]quinoline derivatives
was accomplished in good to excellent yields via the reaction of Schiff base with 1,3-dicarbonyl compounds in aqueous medium cat-
1
alyzed by TEBA. The structures were characterized by H NMR, IR and elemental analysis, and confirmed by X-ray diffraction
study.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Since Breslow demonstrated hydrophobic effects could
strongly enhance the rate of some organic reactions
and rediscovered the use of water as solvent in organic
chemistry in 1980s,1 there has been a growing recogni-
tion that waterhas become an attarctive medium for
many organic reactions, such as Diels–Alder reactions,2
Claisen rearrangement reactions,3 Reformatsky reac-
tions4 and Pinacol-coupling reactions,5 not only for
the advantages concerning the avoidance of expensive
drying reactants, catalysts and solvents, but also for
some unique reactivity and selectivity.6,7 On the other
hand, organic reactions in water without using harmful
organic solvents is one of the current focuses today espe-
cially in the environmentally conscious society, because
water is abundant, nontoxic and environment-friendly
when compared with organic solvents used accordingly.
ture and activity relationship and also provided some
insight into the molecular interactions at the receptor
level. The general method for the synthesis of 1,4-DHPS
is from the reaction of meldrumÕs acid and dimedone in
the presence of different aldehydes catalyzed by ammo-
nium acetate.11 Recently, there are many other methods
available for the construction of tricycle compounds
containing the 1,4-dihydropyridines, for instance acri-
dine derivatives, by heating appropriate aldehyde, dime-
done and ammonium acetate in conventional organic
solvents12 orundermicrowave irradiation. 13 As a conse-
quence of ourinteerst in the aqueous-medium ogranic
syntheses,14 herein, we would like to report a highly effi-
cient method for the synthesis of a series of polyhydro-
acridine derivatives and quinoline derivatives via the
reaction of Schiff base and 1,3-dicarbonyl compounds
in watercatalyzed by TEBA (benzyltirethylammonium
chloride).
1,4-Dihydropyridines (1,4-DHPS) are well-known com-
pounds for their pharmacological profile in calcium
channel modulations.8 The chemical modifications on
the DHP ring, such as different substituents9 orhetero-
atoms,10 have allowed the study of the extended struc-
When the reaction of N-arylidenenaphthalen-1-amine or
N-arylidenequinolin-5-amine 1 and dimedone 2 was
performed in water in the presence of TEBA at 100 ꢁC,
3,3-dimethyl-9-aryl-1,2,3,4,9,10-hexahydrobenzo[c]acri-
dine-1-one derivatives or 3,3-dimethyl-9-aryl-1,2,3,4,
9,10-hexahydropyrido[2,3-c]acridine-1-one derivatives 3
were obtained in high yields (Scheme 1). The results are
summarized in Table 1.
Keywords: Acridine; Quinoline; Schiff base; Aqueous medium; TEBA.
*
Corresponding author. E-mail addresses: xswang1974@yahoo.com;
xswangxznu@yahoo.com.cn
0040-4039/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2005.08.091

7170
X.-S. Wang et al. / Tetrahedron Letters 46 (2005) 7169–7173
Ar
O
Ar
O
O
O
O
O
Ar
+
N
CH
X
TEBA
Water
TEBA
Water
+
N
H
X
N
CH Ar
N
H
4
2
5
1
2
3
Scheme 2.
Scheme 1.
Table 1. Synthesis of 3 in water, catalyzed by TEBA15
Entry Ar Time (h) Products Yield (%)
Table 2. Synthesis of 5 in water, catalyzed by TEBA15
Entry Ar Time (h) Products Yield (%)
X
1
4-ClC6H4
CH 12
CH 18
CH 18
CH 12
3a
3b
3c
3d
3e
3f
93
92
89
91
93
98
81
84
76
83
82
86
1
2
4-ClC6H4
2-ClC6H4
3
3
5a
5b
5c
5d
5e
5f
98
94
97
87
87
96
99
99
98
96
2
3
4
4-OHC6H4
4-CH3OC6H4
4-BrC6H4
3
4
4-CH3OC6H4
4-BrC6H4
5
4
5
3,4-(CH3O)2C6H3 CH 18
5
6
3,4-Cl2C6H3
3,4-(CH3O)2C6H3
2
10
6
2-ClC6H4
CH 12
7
8
9
10
11
12
4-ClC6H4
4-OHC6H4
4-CH3OC6H4
3,4-OCH2OC6H3
3,4-(CH3O)2C6H3
2,4-Cl2C6H3
N
N
N
N
N
N
24
24
24
24
24
18
3g
3h
3i
7
8
9
10
3-CH3O-4-OHC6H3 12
5g
5h
5i
2,4-Cl2C6H3
2-Thiophenyl
3-ClC6H4
2
5
2
3j
5j
3k
3l
different 1,3-dicarbonyl compounds, especially alkyl
chain compounds, such as 2,4-pentanedione and di-
benzoylmethane. Surprisingly, we could not get the
expected benzo[f]quinoline derivatives. According to the
report,16 the pKa value of dimedone (5.2) is lowerthan
those of the above tested compounds (2,4-pentanedione
(9.0), dibenzoyl methane (9.0)).17 We think that the pKa
of the active hydrogen in the 1,3-dicarbonyl compounds
plays a critical role in this reaction. This stimulated us to
find some other1,3-dicarbonyl compounds with low p Ka
as substrates. As a representative, we selected meldrumÕs
acid (pKa 4.3) to prove ourassumption. To ourdelight,
the reaction proceeded smoothly. However, the desired
products 6 were not detected after all, but a series of
benzo[f]quinoline derivatives 7 were obtained, accompa-
nied with a little byproducts of 8 (Scheme 3). The results
are summarized in Table 3.
In order to demonstrate the efficiency and the applicabi-
lity of the present method, we performed the reaction of
a variety of N-arylidenenaphthalen-1-amine or N-aryl-
idenequinolin-5-amine with dimedone in waterat
100 ꢁC and in the presence of TEBA, which behaves as
a phase transfer catalyst. As shown in Table 1, we can
see a series of 1, either bearing electron-withdrawing
groups (such as halide) or electron-donating groups
(such as hydroxyl group and alkoxyl group), reacting
with 2 to give the corresponding products 3 in good
yields under same reaction conditions. Therefore we
concluded that the electronic nature of the substituents
has no significant effect on this reaction.
As expected, when the N-arylidenenaphthalen-1-amine 1
was replaced by N-arylidenenaphthalen-2-amine 4 pre-
pared by the reaction of aromatic aldehydes with
naphthalen-2-amine, anotherseires of 3,3-dimethyl-9-
aryl-1,2,3,4,9,10-hexahydrobenzo[a]acridine-1-one deriva-
tives 5 were obtained under the same reaction conditions
(Scheme 2). The results are summarized in Table 2.
Although the detailed mechanism of the above reaction
has not been clarified yet, the formation of benzo[f]quin-
oline derivatives 7 can be explained by a possible mech-
anism presented in Scheme 4, based on the reference19
that reported that meldrumÕs acid readily lost CO2 and
acetone when heated.
To expand the reaction scope of Schiff base with 1,3-
dicarbonyl compounds, we tried the reaction of 4 with
O
O
Ar
O
o
N
H
N
CH
Ar
o
o
TEBA
H2O
6
+
O
O
Ar
o
O
O
Ar
Ar
+
O
N
H
O
7
8
Scheme 3.

X.-S. Wang et al. / Tetrahedron Letters 46 (2005) 7169–7173
Table 3. Synthesis of 7 and 8 in water, catalyzed by TEBA18
7171
Entry
Ar
Time (h)
Products
Yield (%)
Products
Yield (%)
1
2
3
4
5
4-ClC6H4
4-BrC6H4
2-ClC6H4
3,4-Cl2C6H3
2-Thiophenyl
13
12
12
10
10
7a
7b
7c
7d
7e
81
74
80
78
75
8a
8b
8c
8d
8e
8
10
8
10
11
O
O
O
O
NH2
O
O
4
+
Ar CH
O
O
NH2
H2N
O
O
O
O
O
O
Michael
Addition
CH
Ar
+
O
O
Ar
OH
H
N
H
N
O
O
-CO2
O
-CH3COCH3
O
Ar
Ar
Scheme 4.
Figure 2. ORTEP diagram of 5a.
In a further study, we found that 4-chlorophenyl-
1,2,3,4-tetrahydrobenzo[f]quinolin-2-one 7a was readily
obtained when 4-chlorophenylmethylidenemeldrumÕs
acid was treated with 2-aminonaphthalene in water at
100 ꢁC in the presence of TEBA. It is possible to indicate
from the result that the Michael addition reaction takes
place in the mechanism mentioned above.
1
All the products were characterized by H NMR, IR
spectra and elemental analyses. The structures of 3h,
5a, 7a and 8a were further confirmed by X-ray diffrac-
tion analysis.20 The molecular structures of 3h, 5a, 7a
and 8a are shown in Figures 1–4, respectively.
Figure 3. ORTEP diagram of 7a.
In conclusion, we have developed a novel synthetic
method forthe synthesis of benzo[ c]acridine, benzo[a]-
acridine, pyrido[2,3-c]acridine and benzo[f]quinoline
derivatives in good to excellent yields in aqueous med-
ium. This method has the advantages of good yields,
mild reaction conditions, easy work-up, inexpensive
reagents and being environmentally friendly over the
existing procedures.
Crystallographic data for the structures of 3h, 5a, 7a and
8a reported in this letter have been deposited at the
Cambridge Crystallographic Data Centre as supplemen-
tary publication with No. CCDC-279273, CCDC-
279274, CCDC-279275 and CCDC-279276, respectively.
Figure 1. ORTEP diagram of 3h.

7172
X.-S. Wang et al. / Tetrahedron Letters 46 (2005) 7169–7173
14. (a) Wang, X. S.; Shi, D. Q.; Li, Y. L.; Chen, H.; Wei, X.
Y.; Zong, Z. M. Synth. Commun. 2005, 35, 97; (b) Shi, D.
Q.; Zhang, S.; Zhuang, Q. Y.; Wang, X. S.; Tu, S. J.; Hu,
H. W. Chin. J. Chem. 2003, 21, 680; (c) Wang, X. S.; Shi,
D. Q.; Zhang, Y. F.; Wang, S. H.; Tu, S. J. Chin. J. Org.
Chem. 2004, 24, 430.
15. The general procedure for 3 and 5 is presented as follows:
A mixture of Schiff base 1 or 4 (2 mmol), dimedone 2
(2 mmol) and TEBA (0.1 g) was suspended in water
(10 mL) and stirred at 100 ꢁC for several hours. Upon
completion, monitored by TLC, the reaction mixture was
allowed to cool to room temperature. The crystalline
powderwas collected by filtration, washed with waterand
recrystallized from DMF and water mixture to give pure
acridine derivatives 3 or 5. Compound 3a: mp 263–266 ꢁC;
1H NMR: d 0.98 (s, 3H, CH3), 1.08 (s, 3H, CH3), 2.05 (d,
J = 16.0 Hz, 1H, CH), 2.25 (d, J = 16.0 Hz, 1H, CH), 2.66
(d, J = 16.8 Hz, 1H, CH), 2.73 (d, J = 16.8 Hz, 1H, CH),
5.23 (s, 1H, CH), 7.18–7.28 (m, 5H, ArH), 7.46–7.53 (m,
2H, ArH), 7.57–7.60 (m, 1H, ArH), 7.83 (d, J = 8.4 Hz,
1H, ArH), 8.47 (d, J = 8.4 Hz, 1H, ArH), 9.31 (s, 1H,
NH); IR (KBr, m, cmꢀ1): 3307, 2954, 1672, 1589, 1518,
1384, 1261, 1151, 1089, 1060, 1014, 850, 806, 756. Anal.
Calcd forC 25H22ClNO: C, 77.41; H, 5.72; N, 3.61. Found:
C, 77.34; H, 5.88; N, 3.60. Compound 3h: mp > 300 ꢁC;
1H NMR: 1.08 (s, 3H, CH3), 1.12 (s, 3H, CH3), 2.05 (d,
J = 16.0 Hz, 1H, CH), 2.24 (d, J = 16.0 Hz, 1H, CH), 2.04
(d, J = 17.2 Hz, 1H, CH), 2.69 (d, J = 17.2 Hz, 1H, CH),
5.11 (s, 1H, CH), 6.65 (d, J = 8.4 Hz, 2H, ArH), 7.00 (d,
J = 8.4 Hz, 2H, ArH), 7.49 (d, J = 8.8 Hz, 1H, ArH), 7.55
(d, J = 8.8 Hz, 1H, ArH), 7.57–7.59 (m, 1H, ArH), 8.84 (d,
J = 4.4 Hz, 1H, ArH), 8.90 (d, J = 8.4 Hz, 1H, ArH), 9.12
(s, 1H, NH), 9.35 (s, 1H, OH). IR (KBr, m, cmꢀ1): 3286,
3197, 2957, 1693, 1569, 1490, 1415, 1382, 1262, 1248, 1155,
1066, 831, 790. Anal. Calcd forC 24H22N2O2: C, 77.81; H,
5.99; N, 7.56. Found: C, 77.61; H, 5.87; N, 7.60.
Compound 5a: mp > 300 ꢁC; 1H NMR: 0.84 (s, 3H,
CH3), 1.03 (s, 3H, CH3), 2.02 (d, J = 16.0 Hz, 1H, CH),
2.23 (d, J = 16.0 Hz, 1H, CH), 2.39 (d, J = 16.4 Hz, 1H,
CH), 2.55 (d, J = 16.4 Hz, 1H, CH), 5.79 (s, 1H, CH), 7.19
(d, J = 8.4 Hz, 2H, ArH), 7.24 (d, J = 8.4 Hz, 2H, ArH),
7.30–7.34 (m, 2H, ArH), 7.40–7.44 (m, 1H, ArH), 7.79–
7.82 (m, 2H, ArH), 7.90 (d, J = 8.8 Hz, 1H, ArH), 9.77 (s,
1H, NH). IR (KBr, m, cmꢀ1): 3257, 3076, 2956, 2935, 2873,
1684, 1635, 1578, 1540, 1519, 1500, 1429, 1387, 1258, 1248,
1150, 1086, 1013, 843, 820, 748. Anal. Calcd for
C25H22ClNO: C, 77.41; H, 5.72; N, 3.61. Found: C,
77.28; H, 5.80; N, 3.71.
Figure 4. ORTEP diagram of 8a.
Copies of available material can be obtained, free of
charge, on application to the Director, CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (fax: +44 (0) 1223
336033 ore-mail: deposit@ccdc.cam.ac.uk).
Acknowledgements
We are grateful to the Natural Science Foundation
(04KJB150139) of Jiangsu Education Committee for
financial support.
References and notes
1. (a) Breslow, R.; Rideout, D. C. J. Am. Chem. Soc. 1980,
102, 7816; (b) Breslow, R. Acc. Chem. Res. 1991, 24, 159.
2. Breslow, R.; Maitra, U. Tetrahedron Lett. 1984, 25, 1239.
3. (a) Ponaras, A. A. J. Org. Chem. 1983, 48, 3866; (b)
Coates, R. M.; Rogers, B. D.; Hobbs, S. J.; Peck, D. R.;
Curran, D. P. J. Am. Chem. Soc. 1987, 109, 1160.
4. (a) Mattes, H.; Benezra, C. Tetrahedron Lett. 1985, 26,
5697; (b) Zhou, J. Y.; Lu, G. D.; Wu, S. H. Synth.
Commun. 1992, 22, 481.
16. Villemin, D.; Labiad, B. Synth. Commun. 1990, 20,
3207.
5. Delair, P.; Luche, J. L. J. Chem. Soc., Chem. Commun.
1989, 398.
17. Hu, H. W. Organic Chemistry, 2nd ed.; High Education
Press: Beijing, 2000, p 374.
6. (a) Breslow, R.; Maitra, U.; Rideout, D. C. Tetrahedron
Lett. 1983, 24, 1901; (b) Tan, X. H.; Hou, Y. Q.; Huang,
C.; Liu, L.; Guo, Q. X. Tetrahedron 2004, 60, 6129.
7. (a) Copley, S. D.; Knowles, J. R. J. Am. Chem. Soc. 1987,
109, 5008; (b) Khosropour, A. R.; Khodaei, M. M.;
Kookhazadeh, M. Tetrahedron Lett. 2004, 45, 1725.
8. (a) Janis, R. A.; Silver, P. J.; Triggle, D. J. Adv. Drug Res.
1987, 16, 30; (b) Shan, R.; Velazquez, C.; Knaus, E. E. J.
Med. Chem. 2004, 41, 254; (c) Dulhunty, A. F.; Curtis, S.
M.; Watson, S.; Cengia, L.; Marco, G. J. Biol. Chem.
2004, 279, 11853.
9. Eisner, U.; Kuthan, J. Chem. Rev. 1972, 72, 1.
10. Chorvat, R. J.; Rorig, K. J. J. Org. Chem. 1988, 53, 5779.
11. Sainani, J. B.; Shah, A. C. Indian J. Chem. 1994, 33B, 516.
12. Martin, N.; Quinteiro, M.; Seoane, C.; Mora, L.; Suarez,
M.; Ockoa, E.; Morales, A. J. Heterocycl. Chem. 1995, 51,
235.
18. The general procedure for 7 and 8 is described as follows:
A mixture of Schiff base 4 (2 mmol), meldrumÕs acid
(4 mmol) and TEBA (0.1 g) was suspended in water
(10 mL) and stirred at 100 ꢁC for several hours. Upon
completion, monitored by TLC, the reaction mixture was
allowed to cool to room temperature. The solid was
collected by filtration and washed with water. The solid
was purified by column chromatogaraphy on silica gel
(200–300 mesh) using petroleum ether (bp 60–90ꢁC)–
acetone (1:1) as eluent to give 7 and 8. Compound 7a:
mp 242–243 ꢁC; 1H NMR: d 2.52 (d, J = 14.0 Hz, 1H,
CH), 3.19 (dd, J = 14.0 Hz, J0 = 4.8 Hz, 1H, CH), 5.03 (d,
J = 4.8 Hz, 1H, CH), 7.10 (d, J = 8.4 Hz, 2H, ArH), 7.26–
7.37 (m, 4H, ArH), 7.43 (t, J = 7.6 Hz, 1H, ArH), 7.80 (t,
J = 7.6 Hz, 1H, ArH), 7.85–7.89 (m, 2H, ArH), 10.42 (s,
1H, NH); IR (KBr, m, cmꢀ1): 3196, 3041, 2967, 1676, 1625,
1606, 1524, 1491, 1426, 1243, 1092, 1014, 833, 815, 734.
13. Tu, S. J.; Miao, C. B.; Gao, Y.; Feng, Y. J.; Feng, J. C.
Chin. J. Chem. 2002, 20, 703.

X.-S. Wang et al. / Tetrahedron Letters 46 (2005) 7169–7173
7173
˚
Anal. Calcd forC 19H14ClNO: C, 74.15; H, 4.58; N, 4.55.
0.71070 A) using the
x
scan mode with 3.06ꢁ <
Found: C, 74.25; H, 4.56; N, 4.66. Compound 8a: mp 208–
209 ꢁC; 1H NMR: 0.62 (s, 6H, 2 · CH3), 2.53 (dd,
J = 14.0 Hz, J0 = 4.4 Hz, 2H, CH), 3.44 (t, J = 14.0 Hz,
2H, CH), 4.14 (dd, J = 14.0 Hz, J0 = 4.4 Hz, 2H, CH),
7.18 (d, J = 8.8 Hz, 4H, ArH), 7.48 (d, J = 8.8 Hz, 4H,
ArH); IR (KBr, m, cmꢀ1): 3060, 2999, 2924, 1759, 1727,
1595, 1492, 1417, 1388, 1374, 1310, 1286, 1245, 1196, 1091,
1065, 1013, 984, 912, 893, 839. Anal. Calcd for
C23H20Cl2O5: C, 61.76; H, 4.51. Found: C, 61.82; H, 4.77.
19. (a) Fillion, E.; Fishlock, D. Org. Lett. 2003, 5, 4653; (b)
Gaber, A. E. M.; McNab, H. Synthesis 2001(14), 2059.
20. Crystal data for 3h: C24H22N2O2; M = 370.44, orange-
yellow block crystals, 0.72 · 0.70 · 0.42 mm, tetragonal,
space group P 43 21 2, a = 11.7044(11), b = 11.7044(11),
h < 25.35ꢁ. 3622 unique reflections were measured and
3006 reflections with I > 2r(I) were used in the refinement.
The structure was solved by direct methods and expanded
using Fourier techniques. The final cycle of full-matrix
least squares technique to R = 0.0571 and wR = 0.1186.
Crystal data for 7a: C19H14ClNO; M = 307.76, colourless
block crystals, 0.40 · 0.35 · 0.16 mm, monoclinic, space
groupP21/n,
a = 7.5826(12),
b = 9.0381(11),
c =
3
˚
˚
21.150(3) A, b = 92.333(4)ꢁ, V = 1448.3(4) A , Z = 4,
Dc = 1.411 g cmꢀ3
.
F(000) = 640,
l(Mo Ka) =
0.264 mmꢀ1. Intensity data were collected on a Rigaku
Mercury diffractometer with graphite monochromated
˚
Mo Ka radiation (k = 0.71070 A) using the x scan mode
with 3.61ꢁ < h < 27.48ꢁ. 3318 unique reflections were
measured and 2854 reflection with I > 2r(I) were used in
the refinement. The structure was solved by direct methods
and expanded using Fourier techniques. The final cycle of
full-matrix least squares technique to R = 0.0506 and
wR = 0.1121. Crystal data for 8a: C23H20Cl2O5; M =
447.29, colourless block crystals, 0.60 · 0.59 · 0.20 mm,
monoclinic, space group c2/c, a = 37.432(5), b =
3
˚
c = 28.975(3) A, a = b = c = 90ꢁ, V = 3969.3(7) , Z = 8,
Dc = 1.240 g cmꢀ3
.
F(000) = 1568, l(Mo Ka) = 0.079
mmꢀ1. Intensity data were collected on Rigaku Mercury
diffractometer with graphite monochromated Mo Ka
˚
radiation (k = 0.71070 A) using
x scan mode with
3.24ꢁ < h < 25.35ꢁ. 2154 unique reflections were measured
and 2128 reflections with I > 2r(I) were used in the
refinement. The structure was solved by direct methods
and expanded using Fourier techniques. The final cycle
of full-matrix least squares technique to R = 0.0356
and wR = 0.0855. Crystal data for 5a: C25H22ClNO;
M = 387.89, colourless block crystals, 0.40 · 0.35 ·
˚
9.8988(10), c = 11.5926(14) A, b = 96.534(4)ꢁ, V =
4267.9(9) A , Z = 8, Dc = 1.392 g cmꢀ3. F(000) = 1856,
3
˚
l(Mo Ka) = 0.337 mmꢀ1. Intensity data were collected on
a Rigaku Mercury diffractometer with graphite mono-
˚
chromated Mo Ka radiation (k = 0.71070 A) using the x
0.12 mm, monoclinic, space group P21/n, a =
scan mode with 3.07ꢁ < h < 27.48ꢁ. 4857 unique reflections
were measured and 4486 reflections with I > 2r(I) were
used in the refinement. The structure was solved by direct
methods and expanded using Fourier techniques. The final
cycle of full-matrix least squares technique to R = 0.0477
and wR = 0.1061.
˚
10.4242(14),
b = 11.777(2),
c = 16.173(3) A,
b =
3
ꢀ3
˚
91.024(5)ꢁ, V = 1985.1(5) A , Z = 4, Dc = 1.298 g cm
.
F(000) = 816, l(Mo Ka) = 0.208 mmꢀ1. Intensity data
were collected on a Rigaku Mercury diffractometer with
graphite monochromated Mo Ka radiation (k =