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The benzodiazepine ring in the racemic title compound, C18H15ClN2O3, adopts a boat conformation.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801004093/tk6008sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536801004093/tk6008Isup2.hkl
Contains datablock I

CCDC reference: 162828

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](C-C) = 0.009 Å
  • R factor = 0.075
  • wR factor = 0.214
  • Data-to-parameter ratio = 15.1

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


Yellow Alert Alert Level C:
PLAT_360 Alert C Short C(sp3)-C(sp3) Bond C(14) - C(15) = 1.35 Ang. PLAT_420 Alert C D-H Without Acceptor N(1) - H(1) ? General Notes
ABSTM_02 When printed, the submitted absorption T values will be replaced by the scaled T values. Since the ratio of scaled T's is identical to the ratio of reported T values, the scaling does not imply a change to the absorption corrections used in the study. Ratio of Tmax expected/reported 1.052 Tmax scaled 0.992 Tmin scaled 0.864
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
2 Alert Level C = Please check

Comment top

The configurational stability of chiral 1,4-benzodiazepin-2-ones has been studied in some depth in connection with the difference in pharmacological activity of their enantiomers (Jira et al., 1993; Šunjić et al., 1976). Recently, it was found that the enantiomeric separation of (I) on a chiral HPLC column had been followed by a fast on-column enantiomerization (Abatangelo et al., 2001).

The configurational instability of (I) is due to three double bonds flanking the C3 stereogenic center. Such an arrangement induces a high acidity in the C3—H atom which enables the two tautomeric forms shown in the scheme below. However, the X-ray structure analysis of (I) reveals form (Ia) exclusively (Fig. 1). The molecular structure is characterized by a puckered 1,4-benzodiazepin-2-one ring in the usual boat conformation where C3 deviates significantly from the plane defined by N4, C5, N1 and C2. Bond distances and angles inside the benzodiazepine ring are in accordance with average values of analogous structures. No classic hydrogen bonds are found in the crystal structure.

Experimental top

Compound (I) was obtained from CRC, Compagnia di Ricercha Chimica, Italy. Crystals of (I) were grown by evaporation from an acetonitrile solution of the compound at 277 K.

Refinement top

All H atoms were placed in calculated positions and included in the refinement in the riding model approximation. Some disorder in the ethyl group is evident but multiple sites for these atoms were not resolved.

Computing details top

Data collection: CAD-4 Software (Enraf Nonius, 1989); cell refinement: SET4 and CELDIM in CAD-4 Software (Enraf-Nonius, 1989); data reduction: HELENA (Spek, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: PLATON (Spek, 1990).

Figures top
[Figure 1] Fig. 1. An ORTEPII (Johnson, 1976) drawing of (I) with the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
Ethyl 7-chloro-2,3-dihydro-2-oxo-5-phenyl-1H-1,4-benzodiazepine-3-carboxylate top
Crystal data top
C18H15ClN2O3F(000) = 1424
Mr = 342.77Dx = 1.403 Mg m3
Orthorhombic, PbcaMo Kα radiation, λ = 0.7107 Å
Hall symbol: -P 2ac 2abCell parameters from 25 reflections
a = 15.428 (1) Åθ = 4.4–11.8°
b = 9.346 (2) ŵ = 0.25 mm1
c = 22.506 (5) ÅT = 293 K
V = 3245 (2) Å3Plate, colourless
Z = 80.20 × 0.09 × 0.03 mm
Data collection top
Enraf-Nonius CAD-4
diffractometer
837 reflections with I > 2σ(I)
Radiation source: X-ray tubeRint = 0.081
Graphite monochromatorθmax = 26.3°, θmin = 2.1°
θ/2θ scansh = 019
Absorption correction: ψ scan
(North et al., 1968)
k = 011
Tmin = 0.821, Tmax = 0.943l = 028
3730 measured reflections3 standard reflections every 120 min
3286 independent reflections intensity decay: none
Refinement top
Refinement on F20 restraints
Least-squares matrix: full0 constraints
R[F2 > 2σ(F2)] = 0.075H-atom parameters constrained
wR(F2) = 0.214 w = 1/[σ2(Fo2) + (0.1031P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.84(Δ/σ)max = 0.002
3286 reflectionsΔρmax = 0.34 e Å3
218 parametersΔρmin = 0.54 e Å3
Crystal data top
C18H15ClN2O3V = 3245 (2) Å3
Mr = 342.77Z = 8
Orthorhombic, PbcaMo Kα radiation
a = 15.428 (1) ŵ = 0.25 mm1
b = 9.346 (2) ÅT = 293 K
c = 22.506 (5) Å0.20 × 0.09 × 0.03 mm
Data collection top
Enraf-Nonius CAD-4
diffractometer
837 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.081
Tmin = 0.821, Tmax = 0.9433 standard reflections every 120 min
3730 measured reflections intensity decay: none
3286 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0750 restraints
wR(F2) = 0.214H-atom parameters constrained
S = 0.84Δρmax = 0.34 e Å3
3286 reflectionsΔρmin = 0.54 e Å3
218 parameters
Special details top

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All e.s.d.'s are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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
Cl10.29888 (11)0.32134 (18)0.409440 (9)0.0687 (6)
O100.4591 (3)0.1813 (5)0.14223 (10)0.0667 (19)
O120.3472 (5)0.4576 (6)0.2002 (2)0.106 (3)
O130.2746 (3)0.2977 (5)0.1475 (2)0.075 (2)
N10.4465 (3)0.0007 (6)0.2079 (2)0.0523 (19)
N40.3972 (3)0.2492 (6)0.2808 (2)0.0457 (17)
C20.4249 (4)0.1296 (8)0.1863 (2)0.049 (3)
C30.3585 (4)0.2072 (6)0.2240 (2)0.045 (2)
C50.4084 (4)0.1492 (6)0.3189 (2)0.042 (2)
C60.3557 (3)0.0843 (6)0.3561 (2)0.044 (2)
C70.3398 (4)0.2231 (7)0.3488 (3)0.052 (2)
C80.3562 (4)0.2950 (7)0.2960 (3)0.056 (2)
C90.3899 (4)0.2177 (7)0.2508 (3)0.050 (2)
C110.3270 (5)0.3373 (8)0.1909 (3)0.057 (3)
C140.2369 (8)0.4081 (10)0.1079 (3)0.115 (4)
C150.2723 (9)0.3933 (12)0.0536 (4)0.175 (7)
C160.4433 (4)0.1955 (6)0.3782 (2)0.041 (2)
C170.4134 (4)0.3206 (7)0.4032 (2)0.053 (2)
C180.4411 (5)0.3634 (8)0.4594 (3)0.066 (3)
C190.4977 (5)0.2781 (8)0.4896 (3)0.069 (3)
C200.5297 (5)0.1566 (8)0.4646 (3)0.070 (3)
C210.5021 (4)0.1102 (7)0.4088 (3)0.061 (3)
C510.3898 (3)0.0018 (6)0.3105 (2)0.044 (2)
C910.4071 (3)0.0731 (7)0.2561 (2)0.044 (2)
H10.4887100.0440400.1905800.0625*
H30.3093200.1433500.2315600.0540*
H60.3436900.0416800.3925100.0534*
H80.3445700.3920900.2919500.0672*
H90.4018000.2631500.2149500.0600*
H14A0.2491200.5026600.1234700.1384*
H14B0.1745000.3963100.1056200.1384*
H15A0.2436400.3172000.0327000.2627*
H15B0.2655700.4808800.0317500.2627*
H15C0.3327900.3713800.0574400.2627*
H170.3741300.3770000.3823900.0638*
H180.4214100.4484800.4759500.0793*
H190.5146100.3035000.5277900.0831*
H200.5708700.1033400.4852100.0836*
H210.5223200.0249900.3926400.0726*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0603 (10)0.0627 (10)0.0832 (13)0.0100 (10)0.0037 (10)0.0168 (10)
O100.061 (3)0.100 (4)0.039 (3)0.012 (3)0.010 (2)0.006 (3)
O120.189 (6)0.062 (4)0.067 (4)0.020 (4)0.030 (4)0.001 (3)
O130.088 (4)0.077 (4)0.060 (3)0.006 (3)0.016 (3)0.005 (3)
N10.045 (3)0.066 (4)0.046 (3)0.005 (3)0.009 (3)0.018 (3)
N40.055 (3)0.054 (3)0.028 (3)0.011 (3)0.003 (3)0.007 (3)
C20.047 (4)0.069 (5)0.032 (4)0.005 (4)0.017 (4)0.011 (4)
C30.057 (4)0.045 (4)0.033 (3)0.005 (3)0.007 (3)0.007 (3)
C50.043 (4)0.044 (4)0.038 (4)0.012 (3)0.007 (3)0.006 (3)
C60.044 (4)0.041 (4)0.048 (4)0.001 (3)0.000 (3)0.005 (3)
C70.032 (3)0.044 (4)0.079 (5)0.012 (3)0.010 (3)0.014 (4)
C80.040 (3)0.046 (4)0.082 (5)0.001 (3)0.017 (4)0.020 (4)
C90.048 (4)0.054 (4)0.049 (4)0.004 (3)0.004 (3)0.013 (4)
C110.078 (5)0.054 (5)0.039 (5)0.011 (4)0.010 (4)0.011 (4)
C140.167 (9)0.112 (7)0.067 (6)0.043 (7)0.014 (6)0.019 (6)
C150.229 (14)0.212 (13)0.084 (8)0.043 (11)0.004 (9)0.045 (9)
C160.049 (4)0.041 (4)0.032 (3)0.012 (3)0.011 (3)0.001 (3)
C170.064 (4)0.048 (4)0.048 (4)0.011 (4)0.001 (4)0.002 (4)
C180.070 (5)0.062 (5)0.066 (5)0.016 (4)0.001 (4)0.018 (4)
C190.083 (5)0.069 (5)0.056 (5)0.023 (4)0.000 (5)0.015 (4)
C200.069 (5)0.085 (6)0.055 (5)0.001 (4)0.013 (4)0.006 (4)
C210.064 (4)0.059 (4)0.059 (5)0.010 (4)0.004 (4)0.004 (4)
C510.033 (3)0.054 (4)0.044 (4)0.006 (3)0.003 (3)0.005 (3)
C910.027 (3)0.060 (4)0.044 (4)0.006 (3)0.000 (3)0.004 (4)
Geometric parameters (Å, º) top
Cl1—C71.762 (7)C16—C171.378 (8)
O10—C21.223 (6)C17—C181.393 (8)
O12—C111.186 (9)C18—C191.364 (11)
O13—C111.321 (9)C19—C201.360 (10)
O13—C141.482 (10)C20—C211.395 (10)
N1—C21.353 (9)C51—C911.419 (7)
N1—C911.415 (7)C3—H30.9803
N4—C31.464 (7)C6—H60.9296
N4—C51.280 (7)C8—H80.9299
N1—H10.8603C9—H90.9299
C2—C31.515 (8)C14—H14A0.9696
C3—C111.507 (9)C14—H14B0.9702
C5—C511.453 (8)C15—H15A0.9607
C5—C161.502 (7)C15—H15B0.9608
C6—C511.387 (7)C15—H15C0.9593
C6—C71.331 (9)C17—H170.9297
C7—C81.388 (9)C18—H180.9294
C8—C91.352 (9)C19—H190.9288
C9—C911.383 (9)C20—H200.9308
C14—C151.346 (13)C21—H210.9297
C16—C211.390 (9)
Cl1···C6i3.629 (6)C6···H212.8856
Cl1···C15ii3.489 (10)C8···H3i2.9922
Cl1···C17i3.536 (7)C11···H15C3.0206
Cl1···H15Aii2.8498C16···H1iv3.0702
Cl1···H17iii3.1104C16···H62.7173
Cl1···H6i3.0376C17···H1iv2.8868
O10···O133.049 (7)C19···H18xi2.9487
O10···C7iv3.235 (8)C20···H20x3.0968
O10···C8iv3.178 (8)C21···H62.8500
O12···C9v3.309 (9)C51···H32.5568
O12···N42.771 (8)C51···H212.7670
O12···C8v3.165 (9)C91···H32.5839
O13···O103.049 (7)H1···H92.5092
O10···H19vi2.7169H1···N4viii2.6926
O12···H9v2.7637H1···C16viii3.0702
O12···H14A2.3338H1···C17viii2.8868
O12···H8v2.4975H3···C512.5568
O13···H14Ai2.8351H3···C912.5839
N1···N42.954 (8)H3···C8vii2.9922
N4···O122.771 (8)H6···C162.7173
N4···N12.954 (8)H6···C212.8500
N4···C9iv3.374 (8)H6···Cl1vii3.0376
N4···H172.6035H8···O12iii2.4975
N4···H1iv2.6926H9···O12iii2.7637
C2···C8iv3.472 (9)H9···H12.5092
C2···C9iv3.493 (9)H14A···O122.3338
C6···C213.133 (8)H14A···O13vii2.8351
C6···Cl1vii3.629 (6)H15A···Cl1ix2.8498
C7···O10viii3.235 (8)H15C···C113.0206
C8···O12iii3.165 (9)H17···Cl1v3.1104
C8···O10viii3.178 (8)H17···N42.6035
C8···C2viii3.472 (9)H18···C19xi2.9487
C9···O12iii3.309 (9)H18···H19xi2.5219
C9···C2viii3.493 (9)H19···H18xi2.5219
C9···N4viii3.374 (8)H19···O10xii2.7169
C15···Cl1ix3.489 (10)H20···C20x3.0968
C17···Cl1vii3.536 (7)H21···C62.8856
C20···C20x3.457 (11)H21···C512.7670
C21···C63.133 (8)
C11—O13—C14119.3 (6)C5—C51—C6121.3 (4)
C2—N1—C91126.9 (5)C9—C91—C51119.8 (5)
C3—N4—C5116.3 (5)N1—C91—C9118.9 (5)
C91—N1—H1116.53N1—C91—C51121.1 (5)
C2—N1—H1116.61N4—C3—H3109.12
O10—C2—C3123.8 (6)C2—C3—H3109.19
O10—C2—N1122.7 (6)C11—C3—H3109.14
N1—C2—C3113.4 (4)C7—C6—H6119.34
C2—C3—C11109.2 (5)C51—C6—H6119.26
N4—C3—C2110.0 (5)C7—C8—H8121.44
N4—C3—C11110.3 (5)C9—C8—H8121.51
N4—C5—C51126.6 (5)C8—C9—H9118.95
N4—C5—C16115.6 (5)C91—C9—H9118.93
C16—C5—C51117.8 (4)O13—C14—H14A109.98
C7—C6—C51121.4 (5)O13—C14—H14B109.99
Cl1—C7—C6118.6 (5)C15—C14—H14A110.06
C6—C7—C8123.0 (6)C15—C14—H14B110.06
Cl1—C7—C8118.4 (5)H14A—C14—H14B108.40
C7—C8—C9117.1 (6)C14—C15—H15A109.50
C8—C9—C91122.1 (6)C14—C15—H15B109.45
O13—C11—C3109.7 (6)C14—C15—H15C109.58
O12—C11—O13123.9 (7)H15A—C15—H15B109.35
O12—C11—C3126.4 (7)H15A—C15—H15C109.48
O13—C14—C15108.4 (9)H15B—C15—H15C109.47
C17—C16—C21120.2 (5)C16—C17—H17119.63
C5—C16—C21120.5 (5)C18—C17—H17119.59
C5—C16—C17119.2 (5)C17—C18—H18120.61
C16—C17—C18120.8 (6)C19—C18—H18120.68
C17—C18—C19118.7 (7)C18—C19—H19119.41
C18—C19—C20121.0 (7)C20—C19—H19119.61
C19—C20—C21121.4 (7)C19—C20—H20119.24
C16—C21—C20117.8 (6)C21—C20—H20119.35
C5—C51—C91122.1 (5)C16—C21—H21121.13
C6—C51—C91116.6 (5)C20—C21—H21121.07
C14—O13—C11—C3178.7 (6)N4—C5—C16—C21142.8 (6)
C11—O13—C14—C15111.1 (9)C51—C5—C16—C17139.2 (6)
C14—O13—C11—O120.9 (11)C51—C5—C16—C2137.9 (8)
C91—N1—C2—C37.5 (8)C51—C6—C7—C80.3 (9)
C91—N1—C2—O10175.7 (5)C51—C6—C7—Cl1178.5 (4)
C2—N1—C91—C9136.9 (6)C7—C6—C51—C5179.0 (5)
C2—N1—C91—C5146.7 (8)C7—C6—C51—C910.3 (7)
C3—N4—C5—C512.6 (8)C6—C7—C8—C90.1 (9)
C5—N4—C3—C275.0 (6)Cl1—C7—C8—C9178.1 (5)
C3—N4—C5—C16176.6 (5)C7—C8—C9—C910.4 (9)
C5—N4—C3—C11164.6 (5)C8—C9—C91—C510.4 (8)
O10—C2—C3—C1113.5 (8)C8—C9—C91—N1176.8 (6)
O10—C2—C3—N4107.6 (6)C5—C16—C21—C20177.7 (6)
N1—C2—C3—N469.1 (6)C5—C16—C17—C18176.9 (6)
N1—C2—C3—C11169.8 (5)C17—C16—C21—C200.6 (9)
C2—C3—C11—O1374.0 (7)C21—C16—C17—C180.3 (9)
N4—C3—C11—O1217.1 (10)C16—C17—C18—C190.8 (10)
N4—C3—C11—O13165.1 (5)C17—C18—C19—C202.8 (11)
C2—C3—C11—O12103.7 (8)C18—C19—C20—C213.9 (12)
N4—C5—C16—C1740.0 (8)C19—C20—C21—C162.7 (10)
C16—C5—C51—C91141.5 (5)C5—C51—C91—N12.3 (7)
N4—C5—C51—C9139.4 (9)C5—C51—C91—C9178.6 (5)
N4—C5—C51—C6142.0 (6)C6—C51—C91—N1176.4 (4)
C16—C5—C51—C637.2 (7)C6—C51—C91—C90.0 (7)
Symmetry codes: (i) x+1/2, y1/2, z; (ii) x+1/2, y, z+1/2; (iii) x, y1, z; (iv) x+1, y+1/2, z+1/2; (v) x, y+1, z; (vi) x, y+1/2, z1/2; (vii) x+1/2, y+1/2, z; (viii) x+1, y1/2, z+1/2; (ix) x+1/2, y, z1/2; (x) x+1, y, z+1; (xi) x+1, y+1, z+1; (xii) x, y+1/2, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···N4viii0.8602.6933.368 (9)136.38
Symmetry code: (viii) x+1, y1/2, z+1/2.

Experimental details

Crystal data
Chemical formulaC18H15ClN2O3
Mr342.77
Crystal system, space groupOrthorhombic, Pbca
Temperature (K)293
a, b, c (Å)15.428 (1), 9.346 (2), 22.506 (5)
V3)3245 (2)
Z8
Radiation typeMo Kα
µ (mm1)0.25
Crystal size (mm)0.20 × 0.09 × 0.03
Data collection
DiffractometerEnraf-Nonius CAD-4
diffractometer
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.821, 0.943
No. of measured, independent and
observed [I > 2σ(I)] reflections
3730, 3286, 837
Rint0.081
(sin θ/λ)max1)0.624
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.075, 0.214, 0.84
No. of reflections3286
No. of parameters218
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.34, 0.54

Computer programs: CAD-4 Software (Enraf Nonius, 1989), SET4 and CELDIM in CAD-4 Software (Enraf-Nonius, 1989), HELENA (Spek, 1997), SIR97 (Altomare et al., 1997), SHELXL97 (Sheldrick, 1997), ORTEPII (Johnson, 1976), PLATON (Spek, 1990).

 

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