1-Ethyl-4-phenyl­ethyl-1,4-di­hydro­quinoxaline-2,3-dione

The title compound, C₁₈H₁₈N₂O₂, was synthesized by heating 2,4-dioxo-1,3-di­phenyl-7,8-benzo-6-ethyl-9-(2-phenyl­ethyl)-1,3,6,9-tetr­aza­spiro­[4.4]­nonane in toluene. The quinoxaline ring system is planar and the dihedral angle between the phenyl and piperazine rings is 28.6 (1)°. The crystal structure is stabilized by intermolecular C—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.048
• wR factor = 0.089
• Data-to-parameter ratio = 16.8

checkCIF/PLATON results

No syntax errors found



Alert level C
RINTA01_ALERT_3_C  The value of Rint is greater than 0.10
            Rint given   0.115
PLAT020_ALERT_3_C The value of Rint is greater than 0.10 .........       0.12
PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low ....         40 Perc.

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   3 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

1-Ethyl-4-phenylethyl-1,4-dihydroquinoxaline-2,3-dione

Crystal data

C18H18N2O2	F(000) = 1248
Mr = 294.34	Dx = 1.301 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 6175 reflections
a = 13.369 (5) Å	θ = 2.5–25.3°
b = 15.310 (5) Å	µ = 0.09 mm^−1
c = 14.690 (5) Å	T = 293 K
V = 3006.7 (18) Å^3	Prism, yellow
Z = 8	0.42 × 0.33 × 0.24 mm

Data collection

Stoe IPDS-II diffractometer	1328 reflections with I > 2σ(I)
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus	Rint = 0.115
Plane graphite monochromator	θmax = 27.3°, θmin = 2.5°
Detector resolution: 6.67 pixels mm^-1	h = −14→17
ω scans	k = −19→19
18583 measured reflections	l = −18→18
3351 independent reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.048	H-atom parameters constrained
wR(F^2) = 0.089	w = 1/[σ^2(Fo^2) + (0.0269P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.86	(Δ/σ)max < 0.001
3351 reflections	Δρmax = 0.12 e Å^−3
200 parameters	Δρmin = −0.13 e Å^−3
0 restraints	Extinction correction: SHELXL97, FC^*=KFC[1+0.001XFC^2Λ^3/SIN(2Θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0021 (3)

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su'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 on F^{2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F}2, conventional R-factors R are based on F, with F set to zero for negative F^{2. The observed criterion of F}2 > σ(F^{2) is used only for calculating -R-factor-obs etc. and is not relevant to the choice of reflections for refinement. R-factors based on F}2 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 (Ų)

	x	y	z	Uiso*/Ueq
O1	−0.05202 (15)	−0.05129 (13)	0.68996 (12)	0.0774 (8)
O2	0.06814 (14)	0.06649 (11)	0.77159 (11)	0.0727 (7)
N1	0.07720 (17)	−0.10238 (12)	0.60589 (12)	0.0502 (8)
N2	0.20176 (16)	0.01794 (12)	0.68933 (12)	0.0491 (7)
C1	0.0362 (2)	−0.04810 (16)	0.66858 (17)	0.0558 (10)
C2	0.1035 (2)	0.01706 (16)	0.71393 (16)	0.0538 (10)
C3	0.23935 (19)	−0.03446 (14)	0.61905 (14)	0.0453 (9)
C4	0.3384 (2)	−0.02794 (16)	0.59053 (16)	0.0567 (10)
C5	0.3735 (2)	−0.07847 (17)	0.52005 (18)	0.0623 (10)
C6	0.3116 (2)	−0.13737 (17)	0.47729 (17)	0.0620 (10)
C7	0.2142 (2)	−0.14570 (16)	0.50531 (15)	0.0562 (10)
C8	0.1766 (2)	−0.09440 (15)	0.57624 (15)	0.0463 (9)
C9	0.0084 (2)	−0.16722 (16)	0.56586 (16)	0.0602 (10)
C10	−0.0462 (2)	−0.13048 (18)	0.48477 (18)	0.0781 (11)
C11	0.2659 (2)	0.08072 (14)	0.73797 (15)	0.0568 (9)
C12	0.2710 (2)	0.16879 (15)	0.69052 (16)	0.0686 (10)
C13	0.3116 (2)	0.23783 (14)	0.75304 (15)	0.0518 (9)
C14	0.2486 (2)	0.30135 (16)	0.78803 (16)	0.0607 (10)
C15	0.2835 (2)	0.36296 (16)	0.84839 (18)	0.0658 (10)
C16	0.3818 (2)	0.36286 (17)	0.87375 (18)	0.0671 (13)
C17	0.4460 (2)	0.30130 (17)	0.83918 (17)	0.0637 (10)
C18	0.4111 (2)	0.23878 (16)	0.77933 (16)	0.0582 (10)
H4	0.38120	0.01100	0.61950	0.0680*
H5	0.43960	−0.07280	0.50120	0.0750*
H6	0.33570	−0.17140	0.42960	0.0740*
H7	0.17260	−0.18600	0.47680	0.0670*
H9A	−0.03980	−0.18530	0.61150	0.0720*
H9B	0.04610	−0.21840	0.54730	0.0720*
H10A	−0.09010	−0.17410	0.46020	0.1170*
H10B	0.00140	−0.11340	0.43920	0.1170*
H10C	−0.08450	−0.08050	0.50320	0.1170*
H11A	0.33290	0.05680	0.74290	0.0680*
H11B	0.24020	0.08880	0.79910	0.0680*
H12A	0.31360	0.16420	0.63730	0.0820*
H12B	0.20470	0.18550	0.67030	0.0820*
H14	0.18180	0.30240	0.77050	0.0730*
H15	0.24010	0.40470	0.87190	0.0790*
H16	0.40520	0.40460	0.91450	0.0800*
H17	0.51300	0.30170	0.85610	0.0770*
H18	0.45480	0.19690	0.75650	0.0700*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0558 (14)	0.0927 (14)	0.0836 (13)	0.0023 (11)	0.0097 (11)	−0.0083 (11)
O2	0.0801 (15)	0.0712 (12)	0.0669 (11)	0.0188 (11)	−0.0021 (11)	−0.0177 (10)
N1	0.0513 (15)	0.0497 (12)	0.0497 (12)	−0.0023 (11)	−0.0048 (11)	−0.0035 (10)
N2	0.0531 (15)	0.0474 (12)	0.0467 (11)	0.0010 (10)	−0.0080 (11)	−0.0038 (9)
C1	0.0530 (19)	0.0578 (16)	0.0565 (16)	0.0053 (14)	−0.0009 (14)	0.0019 (13)
C2	0.063 (2)	0.0510 (15)	0.0475 (15)	0.0080 (14)	−0.0066 (14)	0.0017 (12)
C3	0.0490 (18)	0.0459 (13)	0.0411 (13)	0.0026 (13)	−0.0061 (12)	0.0053 (11)
C4	0.055 (2)	0.0565 (16)	0.0587 (16)	−0.0039 (14)	−0.0066 (14)	−0.0008 (13)
C5	0.0521 (18)	0.0725 (19)	0.0622 (17)	0.0047 (16)	0.0022 (15)	0.0071 (15)
C6	0.065 (2)	0.0699 (19)	0.0510 (15)	0.0145 (16)	0.0047 (15)	−0.0047 (13)
C7	0.062 (2)	0.0583 (17)	0.0482 (14)	0.0010 (14)	−0.0076 (14)	−0.0082 (12)
C8	0.0471 (17)	0.0473 (14)	0.0445 (14)	0.0010 (13)	−0.0061 (13)	0.0037 (12)
C9	0.0586 (19)	0.0562 (15)	0.0659 (16)	−0.0097 (14)	−0.0109 (14)	−0.0011 (14)
C10	0.081 (2)	0.078 (2)	0.0752 (18)	0.0001 (17)	−0.0259 (17)	−0.0044 (15)
C11	0.0698 (19)	0.0510 (14)	0.0495 (13)	−0.0073 (14)	−0.0175 (14)	−0.0054 (12)
C12	0.097 (2)	0.0481 (14)	0.0607 (15)	−0.0109 (16)	−0.0219 (16)	0.0078 (13)
C13	0.063 (2)	0.0421 (14)	0.0504 (14)	−0.0049 (14)	−0.0076 (13)	0.0086 (12)
C14	0.0509 (18)	0.0586 (16)	0.0727 (17)	−0.0035 (15)	−0.0084 (15)	0.0116 (14)
C15	0.071 (2)	0.0509 (16)	0.0755 (18)	0.0061 (16)	0.0029 (17)	−0.0006 (14)
C16	0.080 (3)	0.0516 (16)	0.0698 (18)	−0.0091 (17)	−0.0082 (17)	−0.0058 (14)
C17	0.059 (2)	0.0634 (16)	0.0687 (17)	−0.0091 (16)	−0.0128 (15)	0.0051 (14)
C18	0.060 (2)	0.0527 (16)	0.0619 (17)	0.0037 (14)	−0.0001 (15)	0.0030 (13)

Geometric parameters (Å, º)

O1—C1	1.222 (3)	C15—C16	1.366 (4)
O2—C2	1.230 (3)	C16—C17	1.372 (4)
N1—C1	1.356 (3)	C17—C18	1.381 (4)
N1—C8	1.404 (3)	C4—H4	0.93
N1—C9	1.476 (3)	C5—H5	0.93
N2—C2	1.363 (3)	C6—H6	0.93
N2—C3	1.401 (3)	C7—H7	0.93
N2—C11	1.473 (3)	C9—H9A	0.97
C1—C2	1.500 (4)	C9—H9B	0.97
C3—C4	1.393 (4)	C10—H10A	0.96
C3—C8	1.393 (3)	C10—H10B	0.96
C4—C5	1.375 (4)	C10—H10C	0.96
C5—C6	1.376 (4)	C11—H11A	0.97
C6—C7	1.372 (4)	C11—H11B	0.97
C7—C8	1.398 (3)	C12—H12A	0.97
C9—C10	1.506 (4)	C12—H12B	0.97
C11—C12	1.519 (3)	C14—H14	0.93
C12—C13	1.502 (3)	C15—H15	0.93
C13—C14	1.385 (3)	C16—H16	0.93
C13—C18	1.385 (4)	C17—H17	0.93
C14—C15	1.376 (4)	C18—H18	0.93
O1···O2	2.696 (3)	C7···H10B	3.0465
O1···C10	3.250 (3)	C7···H9B	2.5826
O1···C15^i	3.409 (4)	C9···H7	2.5716
O1···C11^ii	3.336 (3)	C10···H7	3.0484
O2···O1	2.696 (3)	C11···H4	2.5582
O2···C12	3.351 (3)	C12···H4	3.0158
O1···H14^i	2.8923	C14···H6^x	3.0909
O1···H15^i	2.7572	C18···H11A	3.0235
O1···H11A^ii	2.4654	H4···C11	2.5582
O1···H9A	2.3589	H4···C12	3.0158
O1···H10C	2.8134	H4···H11A	2.0481
O2···H11B	2.3603	H4···H12A	2.5271
O2···H18^ii	2.5402	H5···H16^viii	2.4410
N1···N2	2.769 (3)	H6···C14^ix	3.0909
N2···N1	2.769 (3)	H6···H11B^ix	2.5108
N2···C15^iii	3.336 (3)	H7···C9	2.5716
C1···C16^iii	3.485 (4)	H7···C10	3.0484
C1···C10^iv	3.545 (4)	H7···H9B	2.0442
C1···C17^iii	3.414 (4)	H9A···O1	2.3589
C2···C16^iii	3.335 (4)	H9A···H14^i	2.5776
C2···C10^iv	3.482 (4)	H9B···C7	2.5826
C2···C15^iii	3.428 (4)	H9B···H7	2.0442
C3···C14^iii	3.537 (3)	H10A···H12B^iv	2.4602
C4···C12	3.470 (4)	H10B···C7	3.0465
C7···C10	3.502 (4)	H10B···C1^iv	2.9788
C10···C7	3.502 (4)	H10B···C2^iv	3.0336
C10···C1^iv	3.545 (4)	H10C···O1	2.8134
C10···O1	3.250 (3)	H10C···C1	2.9584
C10···C2^iv	3.482 (4)	H11A···C4	2.5882
C11···O1^v	3.336 (3)	H11A···C18	3.0235
C12···C4	3.470 (4)	H11A···H4	2.0481
C12···O2	3.351 (3)	H11A···O1^v	2.4654
C14···C3^vi	3.537 (3)	H11B···O2	2.3603
C15···O1^vii	3.409 (4)	H11B···C6^x	2.8079
C15···N2^vi	3.336 (3)	H11B···H6^x	2.5108
C15···C2^vi	3.428 (4)	H12A···C4	3.0390
C16···C1^vi	3.485 (4)	H12A···H4	2.5271
C16···C2^vi	3.335 (4)	H12B···C2	2.9819
C17···C1^vi	3.414 (4)	H12B···H14	2.3374
C1···H10B^iv	2.9788	H12B···H10A^iv	2.4602
C1···H10C	2.9584	H14···H12B	2.3374
C2···H10B^iv	3.0336	H14···O1^vii	2.8923
C2···H12B	2.9819	H14···H9A^vii	2.5776
C4···H11A	2.5882	H15···O1^vii	2.7572
C4···H12A	3.0390	H16···H5^xi	2.4410
C5···H17^viii	2.9964	H17···C5^xi	2.9964
C6···H11B^ix	2.8079	H18···O2^v	2.5402
C1—N1—C8	122.7 (2)	C6—C5—H5	119.79
C1—N1—C9	115.5 (2)	C5—C6—H6	120.16
C8—N1—C9	121.67 (19)	C7—C6—H6	120.17
C2—N2—C3	122.4 (2)	C6—C7—H7	119.61
C2—N2—C11	116.04 (19)	C8—C7—H7	119.54
C3—N2—C11	121.5 (2)	N1—C9—H9A	109.30
O1—C1—N1	122.7 (2)	N1—C9—H9B	109.35
O1—C1—C2	119.5 (2)	C10—C9—H9A	109.34
N1—C1—C2	117.8 (2)	C10—C9—H9B	109.33
O2—C2—N2	123.2 (2)	H9A—C9—H9B	107.98
O2—C2—C1	119.0 (2)	C9—C10—H10A	109.51
N2—C2—C1	117.9 (2)	C9—C10—H10B	109.39
N2—C3—C4	121.5 (2)	C9—C10—H10C	109.47
N2—C3—C8	119.6 (2)	H10A—C10—H10B	109.44
C4—C3—C8	119.0 (2)	H10A—C10—H10C	109.55
C3—C4—C5	120.7 (2)	H10B—C10—H10C	109.46
C4—C5—C6	120.5 (2)	N2—C11—H11A	109.10
C5—C6—C7	119.7 (2)	N2—C11—H11B	109.04
C6—C7—C8	120.8 (2)	C12—C11—H11A	109.13
N1—C8—C3	119.2 (2)	C12—C11—H11B	109.12
N1—C8—C7	121.5 (2)	H11A—C11—H11B	107.83
C3—C8—C7	119.3 (2)	C11—C12—H12A	109.38
N1—C9—C10	111.5 (2)	C11—C12—H12B	109.50
N2—C11—C12	112.50 (19)	C13—C12—H12A	109.38
C11—C12—C13	111.12 (19)	C13—C12—H12B	109.40
C12—C13—C14	120.1 (2)	H12A—C12—H12B	108.01
C12—C13—C18	121.7 (2)	C13—C14—H14	119.57
C14—C13—C18	118.2 (2)	C15—C14—H14	119.50
C13—C14—C15	120.9 (2)	C14—C15—H15	119.93
C14—C15—C16	120.1 (2)	C16—C15—H15	119.99
C15—C16—C17	120.1 (2)	C15—C16—H16	119.90
C16—C17—C18	120.0 (2)	C17—C16—H16	119.99
C13—C18—C17	120.6 (2)	C16—C17—H17	119.95
C3—C4—H4	119.58	C18—C17—H17	120.02
C5—C4—H4	119.71	C13—C18—H18	119.70
C4—C5—H5	119.73	C17—C18—H18	119.69
C8—N1—C1—O1	175.0 (2)	O1—C1—C2—O2	−0.4 (4)
C9—N1—C1—O1	−1.0 (3)	C4—C3—C8—N1	178.8 (2)
C8—N1—C1—C2	−6.1 (3)	N2—C3—C8—N1	−1.4 (3)
C9—N1—C1—C2	177.9 (2)	N2—C3—C8—C7	179.2 (2)
C1—N1—C8—C7	−173.7 (2)	N2—C3—C4—C5	−178.5 (2)
C1—N1—C8—C3	6.8 (3)	C8—C3—C4—C5	1.3 (3)
C9—N1—C8—C3	−177.4 (2)	C4—C3—C8—C7	−0.7 (3)
C8—N1—C9—C10	−89.2 (3)	C3—C4—C5—C6	−1.0 (4)
C9—N1—C8—C7	2.1 (3)	C4—C5—C6—C7	0.0 (4)
C1—N1—C9—C10	86.9 (2)	C5—C6—C7—C8	0.7 (4)
C3—N2—C11—C12	86.7 (3)	C6—C7—C8—C3	−0.3 (4)
C11—N2—C2—C1	−177.82 (19)	C6—C7—C8—N1	−179.8 (2)
C3—N2—C2—O2	−175.4 (2)	N2—C11—C12—C13	164.0 (2)
C2—N2—C3—C4	175.2 (2)	C11—C12—C13—C14	−107.7 (3)
C11—N2—C3—C4	−1.6 (3)	C11—C12—C13—C18	70.5 (3)
C2—N2—C11—C12	−90.4 (2)	C18—C13—C14—C15	−1.0 (4)
C11—N2—C2—O2	1.7 (3)	C12—C13—C18—C17	−177.9 (2)
C3—N2—C2—C1	5.2 (3)	C12—C13—C14—C15	177.3 (2)
C2—N2—C3—C8	−4.6 (3)	C14—C13—C18—C17	0.3 (3)
C11—N2—C3—C8	178.6 (2)	C13—C14—C15—C16	0.9 (4)
O1—C1—C2—N2	179.1 (2)	C14—C15—C16—C17	−0.1 (4)
N1—C1—C2—O2	−179.4 (2)	C15—C16—C17—C18	−0.6 (4)
N1—C1—C2—N2	0.1 (3)	C16—C17—C18—C13	0.5 (4)

Symmetry codes: (i) −x, y−1/2, −z+3/2; (ii) x−1/2, y, −z+3/2; (iii) −x+1/2, y−1/2, z; (iv) −x, −y, −z+1; (v) x+1/2, y, −z+3/2; (vi) −x+1/2, y+1/2, z; (vii) −x, y+1/2, −z+3/2; (viii) −x+1, y−1/2, −z+3/2; (ix) −x+1/2, −y, z−1/2; (x) −x+1/2, −y, z+1/2; (xi) −x+1, y+1/2, −z+3/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C11—H11A···O1^v	0.97	2.47	3.336 (3)	149
C18—H18···O2^v	0.93	2.54	3.453 (3)	167

Symmetry code: (v) x+1/2, y, −z+3/2.