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In the title compound, C18H17N3O2, a strong intramolecular O-H...N hydrogen bond [N...O 2.607 (3), O-H 0.97 (3) and H...N 1.71 (3) Å, and O-H...N 153 (2)°] was observed, which leads to a unique phenol-imine tautomerism in the solid state. The C=N imine bond distance and the C-N-C bond angle [1.287 (2) Å and 121.7 (1)°, respectively] indicate the existence of this phenol-imine tautomer. In solution, the phenol-imine tautomer of the title free Schiff base ligand is dominant in both polar and non-polar solvents, as supported by 1H NMR and UV-visible spectroscopic data.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100015535/os1128sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100015535/os1128Isup2.hkl
Contains datablock I

CCDC reference: 158279

Comment top

2-Hydroxy Schiff base ligands and their transition-metal complexes derived from the reactions of hydroxyaldehyde derivatives with various amines have been extensively studied (Hökelek, Akduran et al., 2000; Hökelek, Işıklan & Kılıç, 2000; Hökelek, Kılıç et al., 2000; Hökelek et al., 1995a,b; Yıldız et al., 1998; Gavranić et al., 1996) and a number of them have been used as models for biological systems (Chen & Martell, 1987; Pyrz et al., 1985; Costamagna et al., 1992). The Schiff base ligand of salicylaldehyde with 4-amino-1,2-dihydro-1,5-dimethyl-2-phenyl-3H-pyrazol-3-one (4-aminophenazone, 4-AAP) has been prepared and various transition-metal complexes of this ligand have been synthesized (Nair & Prabhakaran, 1998; Barton et al., 1987). 4-Aminophenazone and its derivatives are very important compounds in pharmacology and biochemistry (El-Naggar et al., 1981; Lenarcik et al., 1980). They are especially used as anti-inflammatory drugs (Lodzinska et al., 1989).

Aldimine Schiff base ligands are of interest mainly due to the existence of O—H···N and O···H—N types of intramolecular hydrogen bonds and tautomerism between phenol-imine and keto-amine forms (Yıldız et al., 1998; Costamagna et al., 1992; Salman et al., 1991). In these types of ligands, short hydrogen bonds are observed between the 2-hydroxy group and the imine N atom. In some instances, the H atom from the phenol group is completely transferred to the imine N (Hökelek, Akduran et al., 2000; Kaitner & Pavlovic, 1996; Gavranić et al., 1996).

In the solid state, salicylaldimine and naphthaldimine ligands tend to form the N···H—O and N—H···O types of hydrogen bonding, respectively (Hökelek, Işıklan & Kılıç, 2000; Hökelek, Kılıç et al., 2000). In solution, both forms have been observed. Tautomerism in Schiff base ligands is very important for distinguishing their photochromic (Barbara et al., 1980; Hadjoudis, 1981; Higelin & Sixl, 1983; Dürr, 1989; Dürr & Bouas-Laurent, 1990) and thermochromic (Cohen et al., 1964; Moustakali et al., 1978) characteristics.

Although the oxomolybdenum(V) and dioxomolybdenum(VI) complexes of the title compound, (I), have been reported (Nair & Prabhakaran, 1998), the free Schiff base ligand, (I), has not been studied crystallographically. The present structure determination of (I) was undertaken in order to determine the type of hydrogen bonding and to compare the results obtained with those reported previously. The crystallographic atom-numbering of (I) is different from that in the IUPAC name; the latter is not suitable, due to the duplicate C2 atom labels in the salicylidene and phenazone parts. \sch

The molecule of (I) (Fig. 1) contains the bulky 4-aminophenazone-N substituent. It includes a short intramolecular O—H···N hydrogen bond [O1—H1 0.97 (3), H1···N1 1.71 (3) and N1···O1 2.607 (3) Å, and O—H···N 153 (2)°], which means that the ligand is in the phenol-imine form, as in 1,8-di(N-2-oxyphenylsalicylidene)-3,6-dioxaoctane [O—H 1.154 (3), H···N 1.488 (3) and O···N 2.578 (3) Å; Yıldız et al., 1998] and 1,5-di(N-2-oxyphenylsalicylidene)-3-oxapentane [O1—H1 0.864 (4), H1···N1 1.865 (3) and N1···O1 2.587 (4), and O5—H5 1.056 (3), H5···N2 1.603 (4) and N2···O5 2.542 (4) Å; Hökelek, Akduran et al., 2000]. The 1H NMR data for (I) illustrate that the phenol-imine form dominates in CDCl3 solution (δCH = 9.63 and δOH = 13.33 p.p.m., both singlets), supporting the location of the H atom on the O atom.

The C=N imine bond distance and the C—N—C bond angle in (I) [1.287 (3) Å and 121.7 (1)°, respectively] can be compared with the values of 1.270 (3) Å and 123.5 (2)° in 1,8-di(N-2-oxyphenylsalicylidene)-3,6-dioxaoctane (Yıldız et al., 1998), and 1.288 (4) Å and 121.3 (3)°, and 1.277 (4) Å and 124.3 (3)°, in 1,5-di(N-2-oxyphenylsalicylidene)-3-oxapentane (Hökelek, Akduran et al., 2000).

As expected, rings A (C1—C6) and D (C13—C18) are planar, while rings B (N1/H1/O1/C1/C6/C7) and C (N2/N3/C10/C8/C9) are not, with maximum deviations of 0.023 (1) and 0.040 (2) Å from the best least squares planes, respectively. The dihedral angles between the best planes of the rings are A/C 5.7 (6), A/D 131.6 (1), B/C 4.3 (7), B/D 132.8 (1) and C/D 136.4 (1)°. The ΦCN torsion angle (C6—C7—N1—C8) is 177.6 (1)°, which shows that the conformation about the C7—N1 bond is anti (1E). The ΦCN (C11—C10—N3—C12) and ΦNN (C13—N2—N3—C12) torsion angles are -36.9 (3) and 55.7 (2)°, respectively, showing that the conformations about C10—N3 and N2—N3 are gauche. The sums of the bond angles about atoms N2 and N3 are 355.0 (1) and 345.2 (1)°, respectively. In the five-membered ring the puckering parameter, i.e. the angle between the best planes (N3/C8/C9/C10 and N2/N3/C9), is 7.1(1.5)°. The displacements of atoms C12 and C13 from the best plane of the five-membered ring are 0.710 (5) and -0.324 (4)°, respectively, showing that the methyl group bonded to N3 and the phenyl group are on opposite sides of ring C.

The close contact H123(C12)···H181(C18) [2.45 Å query] may cause steric hindrance between the methyl and phenyl groups.

Experimental top

Compound (I) was prepared from a mixture of salicylaldehyde (1.16 g, 9.50 mmol) and 4-aminophenazone (1.93 g, 9.50 mmol) in boiling methanol (100 ml). The precipitate was filtered. The residue was dissolved in CHCl3—MeOH (3:1) and set aside for crystallization (yield 2.58 g, 88%; m.p. 474 K).

Computing details top

Data collection: MolEN (Fair, 1990); cell refinement: MolEN; data reduction: MolEN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: MolEN.

Figures top
[Figure 1] Fig. 1. An ORTEPII (Johnson, 1976) drawing of (I) with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
4-{[(1E)-(2-Hydroxyphenyl)methylidene]amino}-1,5-dimethyl-2-phenyl-1,2-dihydro -3H-pyrazol-3-one top
Crystal data top
C18H17N3O2F(000) = 648
Mr = 307.35Dx = 1.320 Mg m3
Monoclinic, P21/nCu Kα radiation, λ = 1.54180 Å
a = 7.595 (1) ÅCell parameters from 25 reflections
b = 7.498 (1) Åθ = 20–43°
c = 27.277 (2) ŵ = 0.71 mm1
β = 95.332 (7)°T = 293 K
V = 1546.6 (3) Å3Rod, yellow
Z = 40.30 × 0.20 × 0.15 mm
Data collection top
Enraf-Nonius CAD-4
diffractometer
Rint = 0.033
Radiation source: fine-focus sealed tubeθmax = 74.2°, θmin = 3.3°
Graphite monochromatorh = 09
ω/2θ scansk = 09
3226 measured reflectionsl = 3333
3079 independent reflections3 standard reflections every 120 min
2463 reflections with I > 2σ(I) intensity decay: 1%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.066H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.180 w = 1/[σ2Fo2 + (0.1629P)2 + 0.3199P]
where P = (Fo2 + 2Fc2)/3
S = 0.80(Δ/σ)max < 0.001
3079 reflectionsΔρmax = 0.29 e Å3
231 parametersΔρmin = 0.31 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0068 (12)
Crystal data top
C18H17N3O2V = 1546.6 (3) Å3
Mr = 307.35Z = 4
Monoclinic, P21/nCu Kα radiation
a = 7.595 (1) ŵ = 0.71 mm1
b = 7.498 (1) ÅT = 293 K
c = 27.277 (2) Å0.30 × 0.20 × 0.15 mm
β = 95.332 (7)°
Data collection top
Enraf-Nonius CAD-4
diffractometer
Rint = 0.033
3226 measured reflections3 standard reflections every 120 min
3079 independent reflections intensity decay: 1%
2463 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0660 restraints
wR(F2) = 0.180H atoms treated by a mixture of independent and constrained refinement
S = 0.80Δρmax = 0.29 e Å3
3079 reflectionsΔρmin = 0.31 e Å3
231 parameters
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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
xyzUiso*/Ueq
H10.793 (3)0.211 (3)0.0155 (10)0.080 (7)*
N20.5451 (2)0.28689 (18)0.15230 (5)0.0480 (4)
C10.8432 (2)0.3767 (3)0.06089 (6)0.0549 (4)
C20.9142 (3)0.4188 (3)0.10447 (7)0.0680 (6)
H210.94740.32780.12490.079 (7)*
C60.7934 (2)0.5140 (2)0.03010 (6)0.0471 (4)
C30.9362 (3)0.5940 (4)0.11783 (7)0.0701 (6)
H310.98330.62030.14730.076 (7)*
C130.5347 (2)0.3386 (2)0.20201 (6)0.0468 (4)
C40.8887 (3)0.7312 (3)0.08782 (7)0.0659 (5)
H410.90470.84950.09670.071 (6)*
C80.6428 (2)0.2796 (2)0.07716 (6)0.0442 (4)
C50.8175 (3)0.6898 (3)0.04459 (6)0.0570 (5)
H510.78450.78180.02450.083 (7)*
C90.5966 (2)0.3992 (2)0.11537 (5)0.0440 (4)
C70.7229 (2)0.4781 (2)0.01688 (6)0.0473 (4)
H710.69170.57270.03630.048 (5)*
N30.5780 (2)0.10839 (18)0.14065 (5)0.0486 (4)
C110.6569 (4)0.0603 (3)0.06713 (8)0.0671 (6)
H1110.72570.14000.08880.120 (11)*
H1120.71940.03530.03890.142 (13)*
H1130.54530.11460.05670.160 (15)*
C120.4574 (3)0.0266 (2)0.15751 (7)0.0605 (5)
H1210.50080.14340.15070.093 (8)*
H1220.34190.01100.14050.114 (10)*
H1230.45050.01370.19230.080 (7)*
C100.6266 (2)0.1089 (2)0.09357 (6)0.0481 (4)
C140.4297 (2)0.4838 (2)0.21162 (7)0.0520 (4)
H1410.36770.54560.18600.065 (6)*
O10.8262 (2)0.20324 (19)0.04885 (5)0.0733 (5)
C150.4187 (3)0.5352 (3)0.26009 (7)0.0626 (5)
H1510.34900.63240.26690.082 (7)*
O20.60176 (19)0.56281 (16)0.11860 (4)0.0579 (4)
C160.5099 (3)0.4438 (3)0.29837 (7)0.0653 (5)
H1610.50130.47960.33070.074 (7)*
N10.70351 (19)0.31696 (18)0.03167 (5)0.0462 (3)
C170.6137 (3)0.2996 (3)0.28866 (7)0.0613 (5)
H1710.67410.23740.31450.068 (6)*
C180.6281 (2)0.2473 (3)0.24063 (6)0.0529 (4)
H1810.69990.15130.23410.065 (6)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N20.0676 (8)0.0362 (7)0.0418 (7)0.0019 (6)0.0137 (6)0.0009 (5)
C10.0630 (10)0.0592 (11)0.0428 (8)0.0003 (8)0.0067 (7)0.0065 (7)
C20.0722 (12)0.0892 (15)0.0440 (9)0.0020 (11)0.0128 (8)0.0116 (10)
C60.0522 (8)0.0530 (9)0.0365 (8)0.0029 (7)0.0066 (6)0.0004 (6)
C30.0648 (11)0.1057 (19)0.0412 (9)0.0053 (11)0.0120 (8)0.0100 (10)
C130.0542 (8)0.0457 (8)0.0426 (8)0.0014 (7)0.0149 (6)0.0003 (6)
C40.0666 (11)0.0770 (14)0.0545 (10)0.0012 (10)0.0085 (8)0.0206 (9)
C80.0541 (8)0.0398 (8)0.0396 (7)0.0003 (6)0.0089 (6)0.0003 (6)
C50.0662 (10)0.0577 (11)0.0482 (9)0.0042 (8)0.0105 (8)0.0074 (8)
C90.0560 (8)0.0371 (8)0.0402 (7)0.0004 (6)0.0107 (6)0.0012 (5)
C70.0584 (9)0.0444 (8)0.0399 (8)0.0033 (7)0.0095 (6)0.0005 (6)
N30.0674 (8)0.0340 (7)0.0459 (7)0.0011 (6)0.0136 (6)0.0013 (5)
C110.1047 (16)0.0409 (9)0.0582 (11)0.0003 (10)0.0201 (11)0.0045 (8)
C120.0730 (12)0.0446 (10)0.0662 (12)0.0077 (8)0.0193 (9)0.0056 (8)
C100.0604 (9)0.0401 (9)0.0448 (8)0.0007 (7)0.0097 (7)0.0005 (6)
C140.0583 (9)0.0482 (9)0.0513 (9)0.0038 (7)0.0140 (7)0.0011 (7)
O10.1062 (12)0.0572 (9)0.0596 (8)0.0011 (7)0.0242 (8)0.0135 (6)
C150.0717 (11)0.0579 (11)0.0619 (11)0.0011 (9)0.0256 (9)0.0072 (8)
O20.0862 (9)0.0362 (6)0.0542 (7)0.0002 (5)0.0217 (6)0.0003 (5)
C160.0820 (13)0.0726 (13)0.0444 (9)0.0043 (10)0.0219 (8)0.0056 (8)
N10.0567 (7)0.0436 (7)0.0391 (7)0.0011 (6)0.0079 (5)0.0014 (5)
C170.0701 (11)0.0710 (12)0.0440 (9)0.0010 (9)0.0122 (8)0.0057 (8)
C180.0599 (9)0.0531 (10)0.0475 (9)0.0060 (8)0.0139 (7)0.0030 (7)
Geometric parameters (Å, º) top
N2—C91.3963 (19)C7—N11.287 (2)
N2—N31.4034 (18)C7—H710.9300
N2—C131.4194 (19)N3—C101.369 (2)
C1—O11.351 (2)N3—C121.468 (2)
C1—C21.387 (3)C11—C101.487 (2)
C1—C61.403 (2)C11—H1110.9600
C2—C31.378 (4)C11—H1120.9600
C2—H210.9300C11—H1130.9600
C6—C51.392 (2)C12—H1210.9600
C6—C71.459 (2)C12—H1220.9600
C3—C41.383 (3)C12—H1230.9600
C3—H310.9300C14—C151.387 (3)
C13—C141.389 (2)C14—H1410.9300
C13—C181.393 (2)O1—H10.97 (3)
C4—C51.378 (2)C15—C161.380 (3)
C4—H410.9300C15—H1510.9300
C8—C101.366 (2)C16—C171.378 (3)
C8—N11.3916 (19)C16—H1610.9300
C8—C91.443 (2)C17—C181.382 (2)
C5—H510.9300C17—H1710.9300
C9—O21.230 (2)C18—H1810.9300
C9—N2—N3110.14 (12)C10—N3—C12121.76 (14)
C9—N2—C13124.66 (13)N2—N3—C12117.22 (14)
N3—N2—C13120.23 (13)C10—C11—H111109.5
O1—C1—C2118.77 (17)C10—C11—H112109.5
O1—C1—C6121.60 (16)H111—C11—H112109.5
C2—C1—C6119.62 (19)C10—C11—H113109.5
C3—C2—C1120.7 (2)H111—C11—H113109.5
C3—C2—H21119.7H112—C11—H113109.5
C1—C2—H21119.7N3—C12—H121109.5
C5—C6—C1118.35 (16)N3—C12—H122109.5
C5—C6—C7119.50 (15)H121—C12—H122109.5
C1—C6—C7122.12 (16)N3—C12—H123109.5
C2—C3—C4120.55 (17)H121—C12—H123109.5
C2—C3—H31119.7H122—C12—H123109.5
C4—C3—H31119.7C8—C10—N3110.51 (13)
C14—C13—C18120.21 (15)C8—C10—C11128.15 (15)
C14—C13—N2118.55 (15)N3—C10—C11121.34 (14)
C18—C13—N2121.23 (15)C15—C14—C13118.93 (17)
C5—C4—C3118.9 (2)C15—C14—H141120.5
C5—C4—H41120.5C13—C14—H141120.5
C3—C4—H41120.5C1—O1—H1102.1 (15)
C10—C8—N1121.89 (14)C16—C15—C14120.89 (18)
C10—C8—C9108.09 (14)C16—C15—H151119.6
N1—C8—C9129.95 (14)C14—C15—H151119.6
C4—C5—C6121.91 (18)C17—C16—C15119.96 (17)
C4—C5—H51119.0C17—C16—H161120.0
C6—C5—H51119.0C15—C16—H161120.0
O2—C9—N2123.99 (14)C7—N1—C8121.70 (14)
O2—C9—C8131.53 (14)C16—C17—C18120.16 (18)
N2—C9—C8104.45 (13)C16—C17—H171119.9
N1—C7—C6120.71 (15)C18—C17—H171119.9
N1—C7—H71119.6C17—C18—C13119.84 (17)
C6—C7—H71119.6C17—C18—H181120.1
C10—N3—N2106.21 (12)C13—C18—H181120.1
O1—C1—C2—C3179.12 (19)C1—C6—C7—N10.2 (3)
C6—C1—C2—C30.1 (3)C9—N2—N3—C108.16 (18)
O1—C1—C6—C5179.00 (17)C13—N2—N3—C10164.32 (15)
C2—C1—C6—C50.0 (3)C9—N2—N3—C12148.16 (15)
O1—C1—C6—C70.9 (3)C13—N2—N3—C1255.7 (2)
C2—C1—C6—C7178.13 (17)N1—C8—C10—N3175.22 (14)
C1—C2—C3—C40.4 (3)C9—C8—C10—N31.9 (2)
C9—N2—C13—C1456.0 (2)N1—C8—C10—C114.0 (3)
N3—N2—C13—C14151.52 (16)C9—C8—C10—C11178.95 (19)
C9—N2—C13—C18123.67 (19)N2—N3—C10—C86.1 (2)
N3—N2—C13—C1828.9 (2)C12—N3—C10—C8143.83 (16)
C2—C3—C4—C50.7 (3)N2—N3—C10—C11174.68 (17)
C3—C4—C5—C60.6 (3)C12—N3—C10—C1136.9 (3)
C1—C6—C5—C40.2 (3)C18—C13—C14—C150.4 (3)
C7—C6—C5—C4177.91 (17)N2—C13—C14—C15179.97 (16)
N3—N2—C9—O2171.33 (16)C13—C14—C15—C160.2 (3)
C13—N2—C9—O216.5 (3)C14—C15—C16—C170.1 (3)
N3—N2—C9—C86.92 (17)C6—C7—N1—C8177.55 (14)
C13—N2—C9—C8161.79 (15)C10—C8—N1—C7178.20 (16)
C10—C8—C9—O2174.94 (18)C9—C8—N1—C71.8 (3)
N1—C8—C9—O21.8 (3)C15—C16—C17—C180.6 (3)
C10—C8—C9—N23.12 (18)C16—C17—C18—C131.2 (3)
N1—C8—C9—N2179.89 (16)C14—C13—C18—C171.1 (3)
C5—C6—C7—N1178.27 (16)N2—C13—C18—C17179.30 (16)

Experimental details

Crystal data
Chemical formulaC18H17N3O2
Mr307.35
Crystal system, space groupMonoclinic, P21/n
Temperature (K)293
a, b, c (Å)7.595 (1), 7.498 (1), 27.277 (2)
β (°) 95.332 (7)
V3)1546.6 (3)
Z4
Radiation typeCu Kα
µ (mm1)0.71
Crystal size (mm)0.30 × 0.20 × 0.15
Data collection
DiffractometerEnraf-Nonius CAD-4
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
3226, 3079, 2463
Rint0.033
(sin θ/λ)max1)0.624
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.066, 0.180, 0.80
No. of reflections3079
No. of parameters231
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.29, 0.31

Computer programs: MolEN (Fair, 1990), MolEN, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEPII (Johnson, 1976).

Selected geometric parameters (Å, º) top
N2—C91.3963 (19)C8—N11.3916 (19)
N2—N31.4034 (18)C8—C91.443 (2)
N2—C131.4194 (19)C9—O21.230 (2)
C1—O11.351 (2)C7—N11.287 (2)
C6—C71.459 (2)N3—C101.369 (2)
C8—C101.366 (2)O1—H10.97 (3)
C9—N2—N3110.14 (12)N2—C9—C8104.45 (13)
C9—N2—C13124.66 (13)N1—C7—C6120.71 (15)
O1—C1—C6121.60 (16)C10—N3—N2106.21 (12)
C1—C6—C7122.12 (16)N2—N3—C12117.22 (14)
C10—C8—N1121.89 (14)C8—C10—N3110.51 (13)
C10—C8—C9108.09 (14)C8—C10—C11128.15 (15)
N1—C8—C9129.95 (14)C1—O1—H1102.1 (15)
O2—C9—C8131.53 (14)C7—N1—C8121.70 (14)
O1—C1—C6—C70.9 (3)N2—N3—C10—C11174.68 (17)
C13—N2—N3—C10164.32 (15)C12—N3—C10—C1136.9 (3)
C9—N2—N3—C12148.16 (15)C6—C7—N1—C8177.55 (14)
C13—N2—N3—C1255.7 (2)
 

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