The structures of indazolin-3-one (=1,2-dihydro-3H-indazol-3-one) and 7-nitroindazolin-3-one

Article abstract of DOI:10.1002/hlca.200900119

The existence of polymorphism in parent indazolin-3-one (=1,2-dihydro-3H-indazol-3-one; 1) is reported as well as an X-ray and NMRCPMAS study establishing that its 7-nitro derivative 2 exists as the 3-hydroxy tautomer. Absolute shieldings calculated at th

Full text of DOI:10.1002/hlca.200900119

1
952
Helvetica Chimica Acta – Vol. 92 (2009)
The Structures of Indazolin-3-one (¼1,2-Dihydro-3H-indazol-3-one) and
-Nitroindazolin-3-one
7
a
a
a
b
b
by Rosa M. Claramunt* ), Dionisia Sanz ), Concepci o´ n L o´ pez ), Elena Pinilla ), M. Rosario Torres ),
c
d
d
Jos e´ Elguero ), Pierre Nioche ), and C. S. Raman )
a) Departamento de Quꢀmica Org a´ nica y Bio-Org a´ nica, Facultad de Ciencias, UNED, Senda del Rey 9,
E-28040 Madrid (fax: þ 34 – 913988372; e-mail: rclaramunt@ccia.uned.es)
b) Departamento de Quꢀmica Inorg a´ nica I, Laboratorio de Difracci o´ n de Rayos-X, Facultad de Ciencias
Quꢀmicas, UCM, E-28040 Madrid
c) Instituto de Quꢀmica M e´ dica, CSIC, Juan de la Cierva 3, E-28006 Madrid
d) Department of Biochemistry & Molecular Biology, University of Texas Medical School, 6431 Fannin
St., Houston, TX 77030, USA
In memoriam Professor Robert Jacquier of the University of Montpellier (France)
The existence of polymorphism in parent indazolin-3-one (¼1,2-dihydro-3H-indazol-3-one; 1) is
reported as well as an X-ray and NMR CPMAS study establishing that its 7-nitro derivative 2 exists as the
3
-hydroxy tautomer. Absolute shieldings calculated at the GIAO/B3LYP/6-311 þþ G(d,p) level were
used to determine the tautomeric oxo/hydroxy equilibrium in solution, i.e., always the 1H-indazol-3-ol
tautomer predominates.
Introduction. – In 1986, we published a paper where the tautomerism of indazolin-
3
-one (1; 1,2-dihydro-3H-indazol-3-one; Scheme 1) was studied by X-ray crystallog-
13
15
13
raphy and by C- and N-NMR both in solution and C-NMR in the solid state [1].
The main conclusions of this study were that in the solid state, only tautomer 1a was
present, while in (D )DMSO, 85% of 1b and 15% of 1a coexist. Other authors found at
6
the same time and in the same solvent 75 ꢀ 3% of 1b and 25 ꢀ 3% of 1a [2]. This result
is somewhat surprising since in general, the tautomer found in the solid state coincides
with the most abundant tautomer in solution [3].
Scheme 1. Three tautomers of indazolinone 1
After this article was published, the interest on indazolinone 1 remained unabated.
Its main biological significance is related to neuronal nitric oxide synthase (nNOS) and
kinase inhibitors [4]. Four papers have been published on the tautomerism of 1 [5 – 8].
ꢁ
2009 Verlag Helvetica Chimica Acta AG, Zꢂrich

Helvetica Chimica Acta – Vol. 92 (2009)
1953
A paper on the phototautomerization of 1 concludes that the enol 1b dominates in
nonpolar solvents and the keto form 1a in polar and H-bonding solvents, e.g., H O [5].
2
This is in agreement with a very careful study based on pK determinations, that
a
reached the conclusion that in H O, 95% of 1a and 5% of 1b are present [6]. When
2
included in a cyclodextrine, the tautomer present is 1b [7]. Finally, Matos and co-
workers published an experimental and computational thermochemistry study of
indazolin-3-one [8]. This last work reports not only a standard enthalpy of formation of
ꢁ
1
7
0.0 ꢀ 2.2 kJ mol but theoretical calculations of the tautomeric equilibrium (a
positive sign means that tautomer 1b is the most stable): 7.90 (B3LYP/6-31G*), 3.46
(
B3LYP/6-311G**), ꢁ 0.09 (B3LYP/cc-pVTZ), and ꢁ 17.98 (MP2/cc-pVTZ) showing
enormous dispersion. For this reason alone, the tautomerism of indazolin-3-one
deserved to be revisited. Besides, there is interest in the synthesis and reactivity of
indazolin-3-one (1) [9 – 11] and mainly in its biological properties [12][13]. A search in
the Cambridge Structural Database [14] shows that no other structure of N(1),N(2)-
unsubstituted indazolin-3-ones other than that of 1 (refcode FADMIG) has been
published.
In this article, we will examine again indazolinone 1 together with its 7-nitro
derivative 2 (Scheme 2). We have prepared compound 2 within a study program of
inhibitors of the NOS (nitric oxide synthase), where 7-nitroindazole was an active
compound [15 – 18]. All nitroindazolinones are known compounds [19][20], but while
the 5-nitro isomer is rather common and the 6-nitro has been described several times, a
search in the Chemical Abstracts for the 7-nitro isomer 2 (CAS 31775-97-0) between
1987 and 2008 afforded only two patents [12][21]. Furthermore, nothing is known
about the tautomerism of compound 2.
Scheme 2. Three tautomers of 7-nitroindazolinone 2
Results and Discussion. – Theoretical Calculations: Energies and Absolute
Shieldings. We carried out B3LYP/6-311 þþ G(d,p) calculations (see Exper. Part) of
the six molecules of Schemes 1 and 2. We used the optimized geometries (no imaginary
frequencies) to calculate the corresponding absolute shieldings (s, GIAO), and we
1
13
15
transformed s into chemical shifts d by means of Eqns. 1 – 3 (only H, C and
N
17
because we have no data on O) that were obtained by fitting computed shieldings and
experimental chemical shifts [22]:
1
1
d( H) ¼ 31.0 – 0.97 s( H)
(1)
(2)
(3)
13
13
d( C) ¼ 175.7 – 0.963 s( C)
15
15
d( N) ¼ ꢁ148.0 – 0.95 s( N)

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Helvetica Chimica Acta – Vol. 92 (2009)
Concerning the energies, in the case of 1, the minimum is 1b (ꢁ455.194294 hartree)
ꢁ
1
ꢁ1
followed by 1a (24.0 kJ mol ), and the least stable is 1c (41.2 kJ mol ). In the 7-nitro
series, the minimum is also the 1H-indazol-3-ol derivative 2b (ꢁ659.76173 hartree),
ꢁ
1
ꢁ1
then 2a (5.1 kJ mol ) and 2c (70.4 kJ mol ). Although the ordering is the same, in the
gas phase, the 7-nitro group stabilizes the indazolinone 2a and destabilizes the 2H-
indazol-3-ol 2c. The dipole moments [D] are: 5.48 (1a), 1.72 (1b), 2.94 (1c), 0.97 (2a),
3.84 (2b), and 8.28 (2c). The chemical shifts are reported in Table 1.
Table 1. GIAO-Calculated H-, 13C-, and 15N-NMR Chemical Shifts d
1
1a
1b
1c
2a
2b
2c
N(1)
N(2)
N(7) (NO2)
C(3)
C(3a)
C(4)
C(5)
C(6)
C(7)
ꢁ 284.34
ꢁ 241.41
ꢁ
ꢁ 234.25
ꢁ 116.82
ꢁ
ꢁ 121.91
ꢁ 195.53
ꢁ
ꢁ 266.16
ꢁ 233.09
ꢁ 12.03
162.28
121.90
132.89
119.32
128.86
134.80
144.61
7.52
ꢁ 223.00
ꢁ 110.56
ꢁ 11.26
155.10
115.45
129.18
117.70
125.21
132.93
134.99
9.61
ꢁ 114.22
ꢁ 189.85
ꢁ 14.21
146.22
108.98
123.91
116.95
127.44
139.59
140.91
–
154.85
115.69
125.68
117.59
131.34
105.23
140.59
6.07
154.32
111.96
120.50
118.80
127.04
107.06
141.73
7.69
143.88
104.89
115.12
119.48
125.75
120.03
149.04
–
C(7a)
H ꢁ N(1)
H ꢁ N(2)
OH
6.79
–
–
4.83
9.02
4.43
6.28
–
–
5.02
9.26
4.81
HꢁC(4)
HꢁC(5)
HꢁC(6)
HꢁC(7)
7.89
6.81
7.28
6.69
7.72
7.00
7.27
7.06
7.15
6.83
7.14
7.57
8.11
7.05
8.29
–
7.98
7.04
8.27
–
7.50
6.90
8.50
–
The Case of Indazolinone 1. In Table 2, the experimental results concerning
indazolinone 1 are given. The chemical shifts of 1 were reported previously [1]. In the
solid state, they correspond to tautomer 1a whose structure was determined by X-ray
crystallography. When recording the CPMAS (cross-polarization magic-angle spin-
ning) spectra of a commercial sample of 1 (Aldrich 12606, 97%) we discovered another
polymorph. Some signals (of both N-atoms and of C(3), C(3a), and C(7a)) were
splitted (see Fig. 1). Using two solvents, we succeeded in obtaining pure polymorph I
(
in EtOH) and polymorph II (in AcOEt). The NMR chemical shifts of the solid
compound we described in our 1986 paper (see Table 2) correspond to polymorph I (it
was obtained from a MeOH solution) [1].
We excluded that it is a case of desmotropy (two different tautomers). Comparison
of the experimental data (Table 2) with the calculated ones for the three tautomers
(
Table 1) clearly shows that both samples are polymorphs of the same tautomer 1a (we
included the references at d 0.0 in the regressions) (Eqns. 4 and 5). The square
2
correlation coefficients R for calculated 1b and 1c are 0.975 and 0.952 (the same for
both polymorphs).
2
dpolymorphI ¼ (9.4 ꢀ 1.7) þ (0.93 ꢀ 0.01) dcalc. 1a, n ¼ 10, R ¼ 0.999
(4)
(5)
2
dpolymorphII ¼ (9.1 ꢀ 2.2) þ (0.94 ꢀ 0.01) dcalc. 1a, n ¼ 10, R ¼ 0.998

Helvetica Chimica Acta – Vol. 92 (2009)
1955
Table 2. Experimental H-, 13C-, and 15N-NMR Chemical Shifts d of Indazolinone 1
1
CPMAS
1] polymorph I polymorph II
(D )DMSO
(D )HMPA
6
18
[
N(1)
N(2)
C(3)
C(3a)
C(4)
C(5)
C(6)
C(7)
–
–
ꢁ 254.0
ꢁ 213.3
160.2
113.1
121.6
119.7
130.5
113.1
143.2
–
ꢁ 256.5
ꢁ 215.9
165.6
110.3
121.6
119.7
130.5
113.1
146.6
–
ꢁ 234.0
ꢁ 138.1
156.1
112.6
120.2
118.7
127.3
110.3
142.5
ꢁ 226.1
n.o.
155.9
160.8
114.0
123.8
120.3
131.6
111.4
144.3
–
–
–
–
–
113.1
1
3
120.5 ( J ¼ 160.5, J ¼ 7.3)
1
3
117.2 ( J ¼ 158.7, J ¼ 6.6)
1
3
125.6 ( J ¼ 157.1, J ¼ 7.3)
1 3
110.0 ( J ¼ 161.5, J ¼ 7.6)
142.5
C(7a)
H ꢁ N(1)/H ꢁ N(2)
11.29 (br.)
10.55 (vbr.)
7.61 (d)
6.96 (t)
7.28 (m)
7.28 (m)
12.27 (br.)
11.0 (br.)
7.69 (d)
6.80 (t)
7.14 (dd)
OH
–
–
–
–
–
–
–
–
HꢁC(4)
HꢁC(5)
HꢁC(6)
HꢁC(7)
–
–
–
7.18 (dd)
In (D )DMSO solution, we estimated that 85% of 1b and 15% of 1a are present
6
using model compounds as fixed tautomers (replacing NH and OH by MeN and MeO)
[
1]. Now with the calculated values of Table 1, the best fit was obtained for 80% of 1b
2
and 20% of 1a (n ¼ 10, R ¼ 0.9998). Remember that other authors found 75 ꢀ 3% of
1
b and 25 ꢀ 3 of 1a in (D )DMSO [2].
6
1
The H-NMR chemical shifts are of minor use because the most interesting ones,
the NH and OH, are too dependent on specific (i.e., H-bonds) and general interactions
with the solvent.
When we failed to obtain suitable crystals to determine the X-ray structure of the
second polymorph, we decided to generate the powder-diffraction diagram of the
determined polymorph (FADMIG) and to record the powder diffractograms of both
polymorphs (Fig. 2). To our surprise, the already determined structure (FADMIG)
corresponds to polymorph II! We then realized that the X-ray structure was
determined from a crystal obtained by leaving a saturated solution in DMSO to stand
13
at room temperature (the product being insoluble in H O), while the C-NMR
2
CPMAS chemical shifts were measured from a compound purified by crystallization in
MeOH.
The conclusion is that in 1986, we have already obtained both polymorphs: I in
MeOH and II in DMSO but we were not aware of it.
The Case of 7-Nitroindazolinone 2. In the case of 2, we also succeeded in
determining its molecular structure: it corresponds to the 1H-indazol-3-ol tautomer 2b.
Here, this tautomer is the most stable according to the calculations.
The X-ray diffraction analysis of suitable crystals of 2, obtained from EtOH, shows
that the molecule is planar including the NO group in the plane (Fig. 3), and selected
2
bond lengths, angles, and H-bond features are collected in Table 3. As expected, the
distances show the N¼O bond delocalization for the nitro group.

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Helvetica Chimica Acta – Vol. 92 (2009)
Fig. 1. 13C- and 15N-NMR CPMAS Spectra of compound 1
The molecule presents H-bonds with the surrounding molecules as depicted in
Fig. 4: a strong one (O(1)ꢁH(1A) ··· N(2’)) forming dimers linked through a weaker H-
bond interaction (N(1)ꢁH(1B) ··· O(2’)) that gives rise to independent layers parallel
to the (1 0 1) plane.
According to the NMR data of Table 4, the compound in the solid state has
structure 2b, and here again, that was confirmed by the comparison of the experimental
2
chemical shifts with the calculated ones (n ¼ 11, Tables 1 and 4): with 2a R ¼ 0.984,
2
2
with 2b R ¼ 0.997 (exp. ¼ ꢁ(4.4 ꢀ 2.6) þ (1.04 ꢀ 0.02) calc. for 2b), and with 2c R ¼
0
.907. In solution, the best fittings were for (D )DMSO, 98% 2b and 2% 2a (n ¼ 14,
6
2
2
R ¼ 1.000) and for (D )HMPA, 87% 2b and 13% 2a (n ¼ 11, R ¼ 1.000) (HMPA ¼
18
N,N,N,N’,N’,N’-hexamethylphosphoric triamide). In (D )DMSO, the comparison
6
between compounds 1 and 2 shows that the nitro group increases the proportion of b

Helvetica Chimica Acta – Vol. 92 (2009)
1957
Fig. 2. a) Calculated powder diffractogram of FAMDIG (three main peaks at 11.5, 15.5, and 26.5 in 2q
units); b) experimental powder diffractograms of polymorphs II (main peaks at 11.4, 15.4, and 26.5) and I
(
main peaks at 15.5 and 31.3).
tautomer; this appears to be more related to the dipole moments than to the differences
in energy.
Conclusions. – The main conclusions of this study are the final characterization of
both polymorphs of indazolinone 1a and the determination of the structure of its 7-
nitro derivative as being 2b. In (D )DMSO solution, both compounds show a clear
6

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Helvetica Chimica Acta – Vol. 92 (2009)
Fig. 3. An ORTEP view (30% probability level) of
the monomer of 2
Table 3. Selected X-Ray Parameters of Compound 2 Including the H-Bonds. Lengths in ꢃ and angles in 8.
N(1)ꢁN(2)
N(2)ꢁC(3)
C(3)ꢁC(3a)
C(3a)ꢁC(7a)
N(1)ꢁC(7a)
C(3)ꢁO(1)
C(7)ꢁN(3)
N(3)ꢁO(2)
1.385(2)
1.312(2)
1.425(2)
1.410(2)
1.346(2)
1.335(2)
1.441(2)
1.232(2)
N(3)ꢁO(3)
1.223(2)
0.92
0.92
2.715(2)
3.047(2)
1.81
N(1)ꢁN(2)ꢁC(3)
N(2)ꢁC(3)ꢁC(3a)
C(3)ꢁC(3a)ꢁC(7a)
C(3a)ꢁC(7a)ꢁN(1)
C(7a)ꢁN(1)ꢁN(2)
O(2)ꢁN(3)ꢁO(3)
106.3(1)
111.5(1)
103.8(1)
107.6(1)
110.8(1)
122.5(2)
172.3
O(1)ꢁH(1A)
N(1)ꢁH(1B)
a
O(1) ··· N(2) )
b
N(1) ··· O(2) )
a
N(2) ) ··· H(1A)
b
a
O(2) ) ··· H(1B)
2.30
O(1)ꢁH(1A) ··· N(2) )
b
N(1)ꢁH(1B) ··· O(2) )
138.2
a) ꢁ x þ 2, ꢁ y ꢁ 1, ꢁ z þ 1. ) ꢁ x þ 3/2, y ꢁ 1/2, ꢁ z þ 3/2.
b
a
b
Fig. 4. View along the b axis showing the H-bonds O(1)ꢁH(1A) ··· N(2) ) and N(1)ꢁH(1B) ··· O(2) ) in
a
b
compound 2. The H-atoms are omitted for clarity purposes. See Table 3 for ) ).

Helvetica Chimica Acta – Vol. 92 (2009)
1959
Table 4. Experimental H-, 13C-, and 15N-NMR Chemical Shifts d of 7-Nitroindazolinone 2. d in ppm,
1
J in Hz.
CPMAS
(D )DMSO
(D )HMPA
6
18
N(1)
N(2)
N(7) (NO2)
C(3)
C(3a)
C(4)
C(5)
C(6)
C(7)
ꢁ 227.7
ꢁ 138.8
ꢁ 10.1
157.9
121.9
130.4
116.5
126.5
132.1
132.1
–
ꢁ 221.4
ꢁ 113.3
ꢁ 10.6
–
–
–
3
156.4 ( J ¼ 1.8)
157.2
3
3
117.1 ( J ¼ 8.2)
118.6 ( J ¼ 8.0)
1
3
1
3
129.2 ( J¼ 165.0, J ¼ 8.5)
129.4 ( J ¼ 163.1, J ¼ 8.1)
1
1
118.2 ( J ¼ 167.7)
117.5 ( J ¼ 166.8)
1
3
1
3
124.5 ( J¼ 168.4, J ¼ 7.3)
123.6 ( J ¼ 164.6, J ¼ 8.1)
3
131.3
131.9 ( J ¼ 8.9)
3
3
3
3
C(7a)
133.1 ( J ¼ J ¼ 6.8)
133.1 ( J ¼ J ¼ 6.4)
HꢁN(1), HꢁN(2)
12.5 (br.)
13.5 (br.)
OH
–
–
–
–
11.3 (br.)
11.9 (vbr.)
8.25 (d)
7.27 (t)
3
HꢁC(4)
HꢁC(5)
HꢁC(6)
8.14 (d, J ¼ 7.9)
7.16 (t)
3
8.28 (d, J ¼ 7.8)
8.26 (d)
predominance of the 1H-indazol-3-ol tautomers b. The 2H-indazol-3-ol tautomer c was
never observed, in agreement with the DFT calculations, and also with the annular
tautomerism of indazoles [3a][23 – 25].
The tautomerism of indazolinones not substituted at positions 1 and 2 was described
as ꢄconfusedꢅ in 1976 [26] and several years later, in 2000 [3a], the situation had not
much improved save for 1. Our work contributes to improve the situation of this
important class of compounds.
This work has been financed by the Spanish MEC (CTQ2007-62113). We are grateful to Dr. Ibon
Alkorta for helping us with the search in the CSD and Dr. Vicente Ar a´ n for providing us with information
about indazolinones. Work in the laboratory of C.S.R. is funded by the Robert A. Welch Foundation
(
Grant AU-1524) and by the National Institutes of Health (R01 AI054444).
Experimental Part
1. Synthesis of 7-Nitro-1H-indazol-3-ol (2). Compound 2 was prepared by treating ethyl 2-bromo-3-
nitrobenzoate with hydrazine in EtOH soln. (Scheme 3) according to [20]. Yield 84%. M.p. > 3258
1
3
(
EtOH; [20]: 301 – 3058). H-NMR (D (acetone)): 11.77 (br., NH); 10.15 (br., OH); 8.34 (d, J(4,5) ¼ 7.9,
6
3
3
3
1
HꢁC(4)); 7.28 (t, J(4,5) ¼ 7.9, J(5,6) ¼ 7.8, HꢁC(5)); 8.17 (d, J(5,6) ¼ 7.8, HꢁC(6)). H-NMR
3
4
(
CD OD): 13.02 (br., NH); 11.35 (br., OH); 9.60 (dd, J(4,5) ¼ 7.9, J(4,6) ¼ 0.8, HꢁC(4)); 8.53 (t,
3
3
3
3
4
J(4,5) ¼ 7.9, J(5,6) ¼ 7.8 H ꢁC(5)); 9.43 (dd, J(5,6) ¼ 7.8, J(4,6) ¼ 0.8, HꢁC(6)).
2
. Calculations. All calculations were carried out by using the B3LYP hybrid functional [27] with
geometry optimization and frequencies at the B3LYP/6-31G* [28] level and a further optimization at the
B3LYP/6-311 þþ G** level [29], by using the Gaussian 03 facilities [30]. Frequency analyses were
carried out at the same level used in the geometry optimizations, and the nature of the minima was
determined by the absence of negative eigenvalues of the Hessian matrix. Using the B3LYP/6-311 þþ
G** optimized geometries, we have calculated the GIAO absolute shieldings [31].
3
. NMR Spectroscopy. 3.1. In Solution. NMR Spectra: Bruker-DRX-400 (9.4 Tesla) spectrometer; at
1
13
15
4
00.13 ( H), 100.62 ( C), and 40.56 MHz ( N); 5 mm inverse-detection H-X probe equipped with a z-

1
960
Helvetica Chimica Acta – Vol. 92 (2009)
Scheme 3. Synthesis of 2
gradient coil, at 300 K; chemical shifts d in ppm from internal solvent, (D
6
)DMSO d(H) 2.49 and d(C)
15
3
9.5, (D )acetone d(H) 2.05, CD OD d(H) 3.31, (D )HMPA d(H) 2.57 and d(C) 35.82; for N-NMR,
6
3
18
1
13
1
15
MeNO (d(N) 0.00) was used as external standard. 2D ( H, C) gs-HMQC, -HMBC and ( H, N) gs-
2
HMQC, and HMBC: acquired and processed by standard Bruker NMR software and in non-phase-
sensitive mode [32].
3
.2. In the Solid State. 13C (100.73 MHz) and 15N-NMR (40.60 MHz) CPMAS Spectra: Bruker-WB-
4
00 spectrometer; at 300 K with a 4 mm DVT probehead. Samples were carefully packed in a 4 mm
1
diameter cylindrical zirconia rotor with Kel-F end caps. Operating conditions involved 3.2 ms 908 H
pulses and decoupling field strength of 78.1 kHz by TPPM sequence. C-NMR Spectra were originally
13
referenced to a glycine sample, and then the chemical shifts d(C) (in ppm) were recalculated to the Me Si
4
1
5
15
(
C¼O of glycine, d(C) 176.1) and N-NMR spectra to NH Cl and then converted to the MeNO scale
4
2
with the relationship d(N)(MeNO ) ¼ d(N)(NH Cl) ꢁ 338.1. Typical acquisition parameters for
2
4
13
C-NMR CPMAS were: spectral width 40 kHz, recycle delay 40 s for indazolinone 1 and 10 min for
-nitroindazolinone 2, acquisition time 30 ms, contact time 2 ms, and spin rate 12 kHz. To distinguish
7
protonated and unprotonated C-atoms, the NQS (non-quaternary suppression) experiment by conven-
tional cross-polarization was recorded; before the acquisition, the decoupler was switched off for a very
15
short time of 25 ms [33]. Typical acquisition parameters for N-NMR CPMAS were: spectral width
4
3
0 kHz, recycle delay 40 s for indazolinone 1 and 10 min for 7-nitroindazolinone 2, acquisition time
5 ms, contact time 6 ms, and spin rate 6 kHz.
Table 5. Crystal Data and Structure Refinement of 2
Identification code
Empirical formula
Mr
Wavelength [ꢃ]
Crystal system
Space group
Unit cell dimensions
a [ꢃ]
CCDC-721044 Absorption coefficient [mmꢁ1] 0.133
C H N O
F(000)
368
7
5
3
3
179.14
0.71073
Scan technique
q Range [8] for data collection 3.01 – 27.00
w and a
Monoclinic
P2(1)/n
Index ranges
ꢁ 9 ꢂ h ꢂ 9, ꢁ 8 ꢂ k ꢂ 8, ꢁ 17 ꢂ l ꢂ 15
Reflections collected
Independent reflections
Completeness to qmax
Data, restraints, parameters
6184
1673 (R(int) ¼ 0.0470)
7.595(1)
7.007(1)
13.593(1)
94.223(2)
721.4(2)
4
99.49%
b [ꢃ]
c [ꢃ]
1573, 0, 118
1.042
2
Goodness-of-fit on F
a
2
2
b [8]
Volume [ꢃ ]
Final R ) indices (F > 2s (F )) 0.041 (1079 reflections observed)
3
b
2
wR ) (F ) (all data)
0.117
0.209; ꢁ 0.313
Z
Largest diff. peak and
ꢁ
3
Density (calc.)
1.649
hole [e · ꢃ ]
3
[
Mg/m ]
a) S jj F jꢁj F jj /S j F j . b) {S[w(F2
2
)2]/S[w(F2
)2]}1/2
o
c
o
o
ꢁ F
c
o
.

Helvetica Chimica Acta – Vol. 92 (2009)
1961
1
4
. X-Ray Data Collection and Structure Refinement for 2 ). A summary of the fundamental crystal
data and refinement data of 2 is given in Table 5. Ayellow prismatic single crystal was successfully grown
from EtOH and used to collect data with a Bruker-Smart-CCD diffractometer with graphite-
monochromated MoK radiation (l 0.71073 ꢃ) operating at 50 kV and 30 mA. The data were collected
a
over a hemisphere of the reciprocal space by combination of three exposure sets, each exposure was of
2
0 s and covered 0.38 in w. The cell parameters were determined and refined by a least-squares fit of all
reflections collected. The first 100 frames were recollected at the end of the data collection to monitor
crystal decay after X-ray exposition, and no important variation was observed. The structure was solved
by direct methods and difference Fourier techniques and refined by full-matrix least-squares on F2
(
SHELXL-97) [34]. The anisotropic thermal parameters were used in the last cycles of refinement for all
non-H-atoms. The H-atoms in 2 were included at their calculated positions determined by molecular
geometry and refined riding on the respective C-atoms, except for the H(1A) and H(1B) atoms which
were found in difference density maps, included, and refined with coordinates and thermal parameters
fixed. The refinement converged to an R value of 0.041 (Table 5). The calculated XRD patterns were
obtained with the program LAZY PULVERIX [35]. The X-ray powder diffraction was made at r.t. with
a Panalytical XꢀPert PRO a1.
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Received March 31, 2009