rac-(4aR,8aR)-2,3-Diphenyl-4a,5,6,7,8,8a-hexa-hydro-quinoxaline.

The structure of the title racemic compound, C(20)H(20)N(2), shows close similarity to that of the enanti-omerically pure (4aR,8aR)-2,3-diphenyl-4a,5,6,7,8,8a-hexa-hydro-quinoxaline [Wang & Ye (2008 ▶). Acta Cryst. E64, o359-o359]. The similarity applies to the unit-cell parameters as well as to the packing of the constituent mol-ecules. Similar packing is conditioned by a lack of directed inter-molecular inter-actions such as hydrogen bonds in either structure.

Related literature

For examples of the synthesis of non-centrosymmetric solid materials by the reaction of chiral organic ligands and inorganic salts, see: Qu et al. (2004 ▶). For geometric parameters of C=N bonds, see: Figuet et al. (2001 ▶); Kennedy & Reglinski (2001 ▶). For our previous work regarding the enanti­omerically pure (4aR,8aR)-2,3-diphenyl-4a,5,6,7,8,8a-hexa­hydro­quin­ox­aline, see: Wang & Ye (2008 ▶).

Experimental

Crystal data

C20H20N2

M = 288.38

Orthorhombic,

a = 15.278 (3) Å

b = 18.388 (4) Å

c = 5.6638 (11) Å

V = 1591.2 (5) Å3

Z = 4

Mo Kα radiation

μ = 0.07 mm−1

T = 293 (2) K

0.25 × 0.15 × 0.10 mm

Data collection

Rigaku SCXmini diffractometer

Absorption correction: multi-scan (CrystalClear; Rigaku, 2005 ▶) T min = 0.831, T max = 1.000 (expected range = 0.825–0.993)

16117 measured reflections

2004 independent reflections

1558 reflections with I > 2σ(I)

R int = 0.071

Refinement

R[F 2 > 2σ(F 2)] = 0.047

wR(F 2) = 0.100

S = 1.10

2004 reflections

199 parameters

1 restraint

H-atom parameters constrained

Δρmax = 0.13 e Å−3

Δρmin = −0.17 e Å−3

Data collection: CrystalClear (Rigaku, 2005 ▶); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808016103/fb2093sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808016103/fb2093Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C20H20N2	Dx = 1.204 Mg m−3
Mr = 288.38	Melting point = 447–453 K
Orthorhombic, Pna21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2n	Cell parameters from 13431 reflections
a = 15.278 (3) Å	θ = 3.3–27.5°
b = 18.388 (4) Å	µ = 0.07 mm−1
c = 5.6638 (11) Å	T = 293 K
V = 1591.2 (5) Å3	Block, pale yellow
Z = 4	0.25 × 0.15 × 0.10 mm
F(000) = 616

Rigaku SCXmini diffractometer	2004 independent reflections
Radiation source: fine-focus sealed tube	1558 reflections with I > 2σ(I)
graphite	Rint = 0.071
Detector resolution: 13.6612 pixels mm-1	θmax = 27.5°, θmin = 3.5°
ω scans	h = −19→19
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −23→23
Tmin = 0.831, Tmax = 1.000	l = −7→7
16117 measured reflections

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.047	Hydrogen site location: difference Fourier map
wR(F2) = 0.100	H-atom parameters constrained
S = 1.10	w = 1/[σ2(Fo2) + (0.0344P)2 + 0.1949P] where P = (Fo2 + 2Fc2)/3
2004 reflections	(Δ/σ)max < 0.001
199 parameters	Δρmax = 0.13 e Å−3
1 restraint	Δρmin = −0.17 e Å−3
80 constraints

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 > 2µ(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.

	x	y	z	Uiso*/Ueq
C1	0.59529 (17)	0.36737 (13)	0.4260 (5)	0.0432 (6)
H1A	0.5643	0.3988	0.5377	0.052*
C2	0.55215 (16)	0.29231 (13)	0.4296 (6)	0.0531 (7)
H2A	0.5849	0.2594	0.3290	0.064*
H2B	0.5533	0.2731	0.5890	0.064*
C3	0.45847 (19)	0.29648 (16)	0.3444 (7)	0.0626 (9)
H3A	0.4241	0.3243	0.4566	0.075*
H3B	0.4341	0.2478	0.3366	0.075*
C4	0.4523 (2)	0.33176 (15)	0.1036 (7)	0.0666 (10)
H4A	0.3913	0.3367	0.0596	0.080*
H4B	0.4805	0.3008	−0.0123	0.080*
C5	0.49552 (18)	0.40639 (14)	0.1012 (7)	0.0572 (8)
H5A	0.4938	0.4262	−0.0575	0.069*
H5B	0.4635	0.4391	0.2041	0.069*
C6	0.58925 (16)	0.40112 (12)	0.1829 (5)	0.0413 (6)
H6A	0.6214	0.3702	0.0718	0.050*
C7	0.69908 (15)	0.47944 (12)	0.3141 (5)	0.0362 (6)
C8	0.73733 (14)	0.55333 (12)	0.3446 (5)	0.0362 (6)
C9	0.72510 (16)	0.60532 (13)	0.1701 (5)	0.0429 (6)
H9A	0.6967	0.5929	0.0307	0.051*
C10	0.75498 (16)	0.67548 (14)	0.2028 (6)	0.0482 (7)
H10A	0.7464	0.7100	0.0849	0.058*
C11	0.79687 (17)	0.69479 (14)	0.4061 (6)	0.0514 (7)
H11A	0.8164	0.7423	0.4269	0.062*
C12	0.81003 (18)	0.64389 (14)	0.5800 (6)	0.0532 (7)
H12A	0.8391	0.6568	0.7180	0.064*
C13	0.78012 (17)	0.57348 (13)	0.5501 (5)	0.0453 (7)
H13A	0.7888	0.5394	0.6690	0.054*
C14	0.73617 (15)	0.41439 (13)	0.4428 (5)	0.0389 (6)
C15	0.83132 (16)	0.40920 (13)	0.4971 (5)	0.0397 (6)
C16	0.89364 (17)	0.43624 (14)	0.3435 (6)	0.0484 (7)
H16A	0.8761	0.4596	0.2058	0.058*
C17	0.98203 (18)	0.42881 (15)	0.3928 (7)	0.0583 (8)
H17A	1.0234	0.4468	0.2875	0.070*
C18	1.0086 (2)	0.39503 (15)	0.5962 (7)	0.0592 (9)
H18A	1.0680	0.3903	0.6296	0.071*
C19	0.94719 (19)	0.36810 (15)	0.7508 (6)	0.0577 (8)
H19A	0.9652	0.3455	0.8894	0.069*
C20	0.85886 (18)	0.37447 (14)	0.7016 (6)	0.0510 (7)
H20A	0.8178	0.3554	0.8058	0.061*
N1	0.63098 (13)	0.47350 (10)	0.1870 (4)	0.0419 (5)
N2	0.68676 (14)	0.36140 (11)	0.5019 (5)	0.0475 (6)

	U11	U22	U33	U12	U13	U23
C1	0.0398 (14)	0.0371 (14)	0.0528 (17)	0.0033 (11)	0.0011 (13)	0.0030 (13)
C2	0.0423 (15)	0.0418 (15)	0.075 (2)	0.0004 (11)	0.0043 (16)	0.0103 (16)
C3	0.0468 (17)	0.0485 (17)	0.092 (3)	−0.0020 (13)	−0.0008 (17)	0.0044 (18)
C4	0.0511 (17)	0.0546 (18)	0.094 (3)	−0.0083 (14)	−0.0200 (19)	−0.0023 (19)
C5	0.0517 (18)	0.0482 (17)	0.072 (2)	0.0002 (13)	−0.0168 (16)	0.0042 (16)
C6	0.0405 (14)	0.0346 (13)	0.0488 (16)	0.0011 (10)	−0.0028 (13)	−0.0006 (13)
C7	0.0373 (13)	0.0325 (13)	0.0386 (13)	0.0001 (10)	−0.0002 (12)	0.0016 (11)
C8	0.0330 (13)	0.0325 (12)	0.0430 (14)	0.0020 (10)	0.0019 (12)	0.0010 (12)
C9	0.0396 (14)	0.0402 (14)	0.0488 (17)	0.0032 (11)	−0.0021 (13)	0.0051 (13)
C10	0.0448 (14)	0.0376 (14)	0.0622 (18)	0.0005 (11)	0.0078 (16)	0.0099 (14)
C11	0.0486 (16)	0.0362 (14)	0.069 (2)	−0.0068 (12)	0.0058 (16)	−0.0051 (15)
C12	0.0586 (18)	0.0447 (16)	0.0564 (19)	−0.0031 (13)	−0.0055 (15)	−0.0093 (15)
C13	0.0526 (16)	0.0373 (14)	0.0461 (17)	0.0031 (12)	−0.0030 (14)	0.0015 (12)
C14	0.0399 (14)	0.0354 (13)	0.0413 (14)	0.0026 (11)	−0.0009 (12)	0.0014 (12)
C15	0.0413 (14)	0.0286 (12)	0.0492 (16)	0.0052 (11)	−0.0062 (13)	0.0004 (11)
C16	0.0467 (15)	0.0428 (15)	0.0557 (18)	0.0070 (12)	0.0001 (14)	0.0034 (14)
C17	0.0424 (16)	0.0504 (17)	0.082 (3)	0.0058 (13)	0.0053 (16)	−0.0001 (18)
C18	0.0454 (17)	0.0453 (16)	0.087 (2)	0.0093 (13)	−0.0155 (17)	−0.0097 (17)
C19	0.0598 (18)	0.0473 (16)	0.066 (2)	0.0118 (15)	−0.0198 (17)	−0.0003 (15)
C20	0.0545 (17)	0.0424 (14)	0.0561 (18)	0.0018 (13)	−0.0059 (16)	0.0058 (14)
N1	0.0428 (12)	0.0337 (10)	0.0493 (13)	0.0000 (9)	−0.0053 (11)	0.0040 (10)
N2	0.0430 (12)	0.0421 (12)	0.0572 (15)	0.0013 (10)	−0.0049 (12)	0.0115 (11)

C1—N2	1.466 (3)	C9—C10	1.381 (3)
C1—C6	1.513 (4)	C9—H9A	0.9300
C1—C2	1.530 (3)	C10—C11	1.364 (4)
C1—H1A	0.9800	C10—H10A	0.9300
C2—C3	1.512 (4)	C11—C12	1.373 (4)
C2—H2A	0.9700	C11—H11A	0.9300
C2—H2B	0.9700	C12—C13	1.384 (3)
C3—C4	1.513 (5)	C12—H12A	0.9300
C3—H3A	0.9700	C13—H13A	0.9300
C3—H3B	0.9700	C14—N2	1.277 (3)
C4—C5	1.522 (4)	C14—C15	1.489 (3)
C4—H4A	0.9700	C15—C16	1.382 (4)
C4—H4B	0.9700	C15—C20	1.388 (4)
C5—C6	1.508 (4)	C16—C17	1.386 (4)
C5—H5A	0.9700	C16—H16A	0.9300
C5—H5B	0.9700	C17—C18	1.370 (5)
C6—N1	1.476 (3)	C17—H17A	0.9300
C6—H6A	0.9800	C18—C19	1.376 (5)
C7—N1	1.270 (3)	C18—H18A	0.9300
C7—C8	1.489 (3)	C19—C20	1.383 (4)
C7—C14	1.511 (3)	C19—H19A	0.9300
C8—C13	1.385 (4)	C20—H20A	0.9300
C8—C9	1.387 (3)
N2—C1—C6	110.8 (2)	C13—C8—C7	121.8 (2)
N2—C1—C2	109.8 (2)	C9—C8—C7	119.6 (2)
C6—C1—C2	110.8 (2)	C10—C9—C8	120.2 (3)
N2—C1—H1A	108.4	C10—C9—H9A	119.9
C6—C1—H1A	108.4	C8—C9—H9A	119.9
C2—C1—H1A	108.4	C11—C10—C9	120.8 (3)
C3—C2—C1	111.0 (2)	C11—C10—H10A	119.6
C3—C2—H2A	109.4	C9—C10—H10A	119.6
C1—C2—H2A	109.4	C10—C11—C12	119.8 (2)
C3—C2—H2B	109.4	C10—C11—H11A	120.1
C1—C2—H2B	109.4	C12—C11—H11A	120.1
H2A—C2—H2B	108.0	C11—C12—C13	120.1 (3)
C2—C3—C4	111.6 (3)	C11—C12—H12A	119.9
C2—C3—H3A	109.3	C13—C12—H12A	119.9
C4—C3—H3A	109.3	C12—C13—C8	120.6 (3)
C2—C3—H3B	109.3	C12—C13—H13A	119.7
C4—C3—H3B	109.3	C8—C13—H13A	119.7
H3A—C3—H3B	108.0	N2—C14—C15	118.3 (2)
C3—C4—C5	111.6 (3)	N2—C14—C7	120.6 (2)
C3—C4—H4A	109.3	C15—C14—C7	121.1 (2)
C5—C4—H4A	109.3	C16—C15—C20	118.8 (2)
C3—C4—H4B	109.3	C16—C15—C14	121.3 (2)
C5—C4—H4B	109.3	C20—C15—C14	119.9 (2)
H4A—C4—H4B	108.0	C15—C16—C17	120.6 (3)
C6—C5—C4	110.5 (2)	C15—C16—H16A	119.7
C6—C5—H5A	109.5	C17—C16—H16A	119.7
C4—C5—H5A	109.5	C18—C17—C16	120.2 (3)
C6—C5—H5B	109.5	C18—C17—H17A	119.9
C4—C5—H5B	109.5	C16—C17—H17A	119.9
H5A—C5—H5B	108.1	C17—C18—C19	119.7 (3)
N1—C6—C5	110.92 (19)	C17—C18—H18A	120.1
N1—C6—C1	109.2 (2)	C19—C18—H18A	120.1
C5—C6—C1	111.3 (2)	C18—C19—C20	120.5 (3)
N1—C6—H6A	108.4	C18—C19—H19A	119.8
C5—C6—H6A	108.4	C20—C19—H19A	119.8
C1—C6—H6A	108.4	C19—C20—C15	120.2 (3)
N1—C7—C8	117.8 (2)	C19—C20—H20A	119.9
N1—C7—C14	120.8 (2)	C15—C20—H20A	119.9
C8—C7—C14	121.3 (2)	C7—N1—C6	116.1 (2)
C13—C8—C9	118.5 (2)	C14—N2—C1	115.4 (2)
N2—C1—C6—N1	−58.1 (3)