1,4-Bis(3-methyl-phen-yl)piperazine-2,5-dione.

The asymmetric unit of the title compound, C(18)H(18)N(2)O(2), consists of two independent mol-ecules, each of which is located about a center of inversion. The mol-ecules are not planar, showing dihedral angles of 55.84 (9) and 54.10 (8)° between the piperazinedione and the aromatic rings. The piperazine N atoms exhibit a planar configuration. The crystal packing is stabilized by inter-molecular C-H⋯O hydrogen bonds.

Related literature

For background to the applications of piperazinedione and its derivatives, see: Acharya et al. (2001 ▶); Fischer (2003 ▶); Krchnak et al. (1996 ▶); Paradisi et al. (2002 ▶). For the syntheses and structures of piperazinediones, see: Wen et al. (2006 ▶); Zhang et al. (2007 ▶).

Experimental

Crystal data

C18H18N2O2

M = 294.34

Monoclinic,

a = 12.6608 (15) Å

b = 6.1508 (7) Å

c = 19.223 (2) Å

β = 95.142 (2)°

V = 1490.9 (3) Å3

Z = 4

Mo Kα radiation

μ = 0.09 mm−1

T = 153 K

0.38 × 0.12 × 0.10 mm

Data collection

Bruker SMART CCD area-detector diffractometer

Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T min = 0.968, T max = 0.991

7835 measured reflections

2836 independent reflections

2078 reflections with I > 2σ(I)

R int = 0.029

Refinement

R[F 2 > 2σ(F 2)] = 0.052

wR(F 2) = 0.137

S = 1.02

2836 reflections

199 parameters

H-atom parameters constrained

Δρmax = 0.19 e Å−3

Δρmin = −0.22 e Å−3

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT (Bruker, 2001 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812026372/zq2169sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812026372/zq2169Isup2.hkl

Supplementary material file. DOI: 10.1107/S1600536812026372/zq2169Isup3.cml

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

C18H18N2O2	F(000) = 624
Mr = 294.34	Dx = 1.311 Mg m−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 1825 reflections
a = 12.6608 (15) Å	θ = 3.2–23.9°
b = 6.1508 (7) Å	µ = 0.09 mm−1
c = 19.223 (2) Å	T = 153 K
β = 95.142 (2)°	Block, colourless
V = 1490.9 (3) Å3	0.38 × 0.12 × 0.10 mm
Z = 4

Bruker SMART CCD area-detector diffractometer	2836 independent reflections
Radiation source: fine-focus sealed tube	2078 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.029
phi and ω scans	θmax = 25.7°, θmin = 1.9°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −15→15
Tmin = 0.968, Tmax = 0.991	k = −7→7
7835 measured reflections	l = −23→12

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)] = 0.052	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.137	H-atom parameters constrained
S = 1.02	w = 1/[σ2(Fo2) + (0.0664P)2 + 0.2932P] where P = (Fo2 + 2Fc2)/3
2836 reflections	(Δ/σ)max < 0.001
199 parameters	Δρmax = 0.19 e Å−3
0 restraints	Δρmin = −0.22 e Å−3

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.

	x	y	z	Uiso*/Ueq
O2	0.14816 (10)	0.1901 (2)	0.50117 (7)	0.0517 (4)
N2	0.09833 (10)	0.5171 (2)	0.54147 (8)	0.0372 (4)
O1	0.53271 (11)	1.1732 (2)	0.59161 (8)	0.0571 (4)
N1	0.58560 (11)	1.5000 (2)	0.55280 (8)	0.0423 (4)
C15	0.19661 (13)	0.5530 (3)	0.58423 (9)	0.0369 (4)
C16	0.08291 (13)	0.3358 (3)	0.50265 (9)	0.0383 (4)
C14	0.25272 (14)	0.7430 (3)	0.57627 (10)	0.0432 (5)
H14A	0.2275	0.8470	0.5438	0.052*
C6	0.67677 (14)	1.5123 (3)	0.60368 (10)	0.0434 (5)
C7	0.52080 (14)	1.3255 (3)	0.55088 (11)	0.0431 (5)
C1	0.75220 (14)	1.3485 (3)	0.60645 (10)	0.0442 (5)
H1A	0.7416	1.2280	0.5774	0.053*
C10	0.23305 (13)	0.4011 (3)	0.63376 (9)	0.0410 (5)
H10A	0.1942	0.2748	0.6391	0.049*
C13	0.34654 (15)	0.7763 (3)	0.61707 (11)	0.0499 (5)
H13A	0.3853	0.9026	0.6116	0.060*
C8	0.56977 (15)	1.6836 (3)	0.50490 (11)	0.0487 (5)
H8A	0.6345	1.7026	0.4821	0.058*
H8B	0.5608	1.8130	0.5326	0.058*
C17	0.02008 (14)	0.6913 (3)	0.54148 (11)	0.0480 (5)
H17A	0.0532	0.8236	0.5267	0.058*
H17B	0.0038	0.7134	0.5893	0.058*
C12	0.38306 (15)	0.6248 (3)	0.66558 (11)	0.0505 (5)
H12A	0.4468	0.6493	0.6924	0.061*
C11	0.32667 (14)	0.4345 (3)	0.67562 (10)	0.0443 (5)
C5	0.69087 (17)	1.6911 (3)	0.64691 (11)	0.0563 (6)
H5A	0.6405	1.8015	0.6450	0.068*
C9	0.92602 (17)	1.1862 (4)	0.65370 (13)	0.0715 (7)
H9A	0.9037	1.0751	0.6205	0.107*
H9B	0.9353	1.1243	0.6997	0.107*
H9C	0.9920	1.2472	0.6420	0.107*
C4	0.78057 (19)	1.7042 (4)	0.69301 (12)	0.0656 (7)
H4A	0.7901	1.8230	0.7229	0.079*
C2	0.84310 (15)	1.3621 (4)	0.65189 (10)	0.0507 (5)
C18	0.36529 (18)	0.2729 (4)	0.73046 (12)	0.0676 (7)
H18A	0.3167	0.1528	0.7298	0.101*
H18B	0.3697	0.3412	0.7755	0.101*
H18C	0.4341	0.2210	0.7211	0.101*
C3	0.85602 (18)	1.5430 (4)	0.69520 (12)	0.0637 (6)
H3A	0.9166	1.5552	0.7261	0.076*

	U11	U22	U33	U12	U13	U23
O2	0.0451 (8)	0.0387 (7)	0.0687 (9)	0.0118 (6)	−0.0098 (7)	−0.0062 (7)
N2	0.0339 (8)	0.0303 (8)	0.0456 (9)	0.0019 (6)	−0.0069 (7)	0.0003 (7)
O1	0.0545 (8)	0.0430 (8)	0.0724 (10)	−0.0054 (6)	−0.0018 (7)	0.0148 (7)
N1	0.0392 (8)	0.0338 (8)	0.0535 (10)	−0.0026 (6)	0.0027 (7)	0.0021 (7)
C15	0.0342 (9)	0.0362 (9)	0.0392 (10)	0.0025 (7)	−0.0029 (8)	−0.0016 (8)
C16	0.0383 (9)	0.0311 (9)	0.0445 (11)	0.0019 (7)	−0.0019 (8)	0.0034 (8)
C14	0.0472 (11)	0.0374 (10)	0.0439 (10)	−0.0030 (8)	−0.0015 (9)	0.0029 (9)
C6	0.0432 (10)	0.0423 (10)	0.0455 (11)	−0.0072 (8)	0.0087 (9)	0.0010 (9)
C7	0.0400 (10)	0.0313 (9)	0.0592 (12)	0.0005 (8)	0.0102 (9)	0.0007 (9)
C1	0.0455 (11)	0.0457 (11)	0.0413 (11)	−0.0040 (9)	0.0031 (9)	−0.0003 (9)
C10	0.0378 (10)	0.0401 (10)	0.0441 (10)	−0.0011 (8)	−0.0018 (9)	0.0047 (9)
C13	0.0447 (11)	0.0495 (11)	0.0544 (12)	−0.0134 (9)	−0.0009 (10)	−0.0011 (10)
C8	0.0428 (10)	0.0357 (10)	0.0672 (14)	−0.0047 (8)	0.0027 (10)	0.0067 (10)
C17	0.0431 (10)	0.0355 (10)	0.0621 (13)	0.0075 (8)	−0.0134 (10)	−0.0099 (9)
C12	0.0364 (10)	0.0625 (13)	0.0506 (12)	−0.0052 (9)	−0.0078 (9)	−0.0038 (10)
C11	0.0387 (10)	0.0530 (12)	0.0401 (10)	0.0060 (9)	−0.0025 (8)	0.0015 (9)
C5	0.0569 (13)	0.0472 (12)	0.0662 (14)	−0.0086 (10)	0.0129 (11)	−0.0103 (11)
C9	0.0516 (13)	0.0829 (17)	0.0775 (17)	0.0030 (12)	−0.0078 (12)	0.0164 (14)
C4	0.0691 (15)	0.0647 (15)	0.0635 (15)	−0.0252 (12)	0.0093 (13)	−0.0206 (12)
C2	0.0451 (11)	0.0616 (13)	0.0454 (11)	−0.0088 (10)	0.0037 (9)	0.0078 (10)
C18	0.0633 (14)	0.0744 (15)	0.0606 (14)	0.0066 (12)	−0.0191 (12)	0.0146 (13)
C3	0.0527 (13)	0.0801 (17)	0.0565 (13)	−0.0237 (12)	−0.0040 (11)	−0.0001 (13)

O2—C16	1.221 (2)	C8—C7ii	1.499 (3)
N2—C16	1.346 (2)	C8—H8A	0.9700
N2—C15	1.445 (2)	C8—H8B	0.9700
N2—C17	1.459 (2)	C17—C16i	1.500 (2)
O1—C7	1.221 (2)	C17—H17A	0.9700
N1—C7	1.349 (2)	C17—H17B	0.9700
N1—C6	1.446 (2)	C12—C11	1.393 (3)
N1—C8	1.460 (2)	C12—H12A	0.9300
C15—C10	1.383 (2)	C11—C18	1.499 (3)
C15—C14	1.383 (2)	C5—C4	1.379 (3)
C16—C17i	1.500 (2)	C5—H5A	0.9300
C14—C13	1.379 (3)	C9—C2	1.505 (3)
C14—H14A	0.9300	C9—H9A	0.9600
C6—C5	1.380 (3)	C9—H9B	0.9600
C6—C1	1.386 (3)	C9—H9C	0.9600
C7—C8ii	1.499 (3)	C4—C3	1.375 (3)
C1—C2	1.384 (3)	C4—H4A	0.9300
C1—H1A	0.9300	C2—C3	1.391 (3)
C10—C11	1.387 (2)	C18—H18A	0.9600
C10—H10A	0.9300	C18—H18B	0.9600
C13—C12	1.369 (3)	C18—H18C	0.9600
C13—H13A	0.9300	C3—H3A	0.9300
C16—N2—C15	121.08 (14)	N2—C17—C16i	118.32 (15)
C16—N2—C17	122.92 (14)	N2—C17—H17A	107.7
C15—N2—C17	115.97 (14)	C16i—C17—H17A	107.7
C7—N1—C6	120.45 (16)	N2—C17—H17B	107.7
C7—N1—C8	123.32 (15)	C16i—C17—H17B	107.7
C6—N1—C8	116.22 (14)	H17A—C17—H17B	107.1
C10—C15—C14	120.26 (16)	C13—C12—C11	121.34 (17)
C10—C15—N2	120.36 (15)	C13—C12—H12A	119.3
C14—C15—N2	119.37 (15)	C11—C12—H12A	119.3
O2—C16—N2	123.79 (16)	C10—C11—C12	117.77 (17)
O2—C16—C17i	117.46 (16)	C10—C11—C18	121.18 (18)
N2—C16—C17i	118.75 (15)	C12—C11—C18	121.04 (17)
C13—C14—C15	119.16 (17)	C4—C5—C6	119.2 (2)
C13—C14—H14A	120.4	C4—C5—H5A	120.4
C15—C14—H14A	120.4	C6—C5—H5A	120.4
C5—C6—C1	120.31 (18)	C2—C9—H9A	109.5
C5—C6—N1	120.09 (18)	C2—C9—H9B	109.5
C1—C6—N1	119.54 (16)	H9A—C9—H9B	109.5
O1—C7—N1	123.53 (18)	C2—C9—H9C	109.5
O1—C7—C8ii	118.20 (16)	H9A—C9—H9C	109.5
N1—C7—C8ii	118.26 (17)	H9B—C9—H9C	109.5
C2—C1—C6	120.76 (18)	C3—C4—C5	120.5 (2)
C2—C1—H1A	119.6	C3—C4—H4A	119.7
C6—C1—H1A	119.6	C5—C4—H4A	119.7
C15—C10—C11	120.95 (17)	C1—C2—C3	118.2 (2)
C15—C10—H10A	119.5	C1—C2—C9	120.7 (2)
C11—C10—H10A	119.5	C3—C2—C9	121.12 (19)
C12—C13—C14	120.50 (18)	C11—C18—H18A	109.5
C12—C13—H13A	119.8	C11—C18—H18B	109.5
C14—C13—H13A	119.8	H18A—C18—H18B	109.5
N1—C8—C7ii	118.38 (15)	C11—C18—H18C	109.5
N1—C8—H8A	107.7	H18A—C18—H18C	109.5
C7ii—C8—H8A	107.7	H18B—C18—H18C	109.5
N1—C8—H8B	107.7	C4—C3—C2	121.0 (2)
C7ii—C8—H8B	107.7	C4—C3—H3A	119.5
H8A—C8—H8B	107.1	C2—C3—H3A	119.5
C16—N2—C15—C10	−55.7 (2)	C14—C15—C10—C11	−0.8 (3)
C17—N2—C15—C10	126.27 (19)	N2—C15—C10—C11	−179.35 (17)
C16—N2—C15—C14	125.74 (19)	C15—C14—C13—C12	−0.9 (3)
C17—N2—C15—C14	−52.3 (2)	C7—N1—C8—C7ii	−2.2 (3)
C15—N2—C16—O2	1.0 (3)	C6—N1—C8—C7ii	177.36 (16)
C17—N2—C16—O2	178.81 (19)	C16—N2—C17—C16i	1.3 (3)
C15—N2—C16—C17i	−179.17 (17)	C15—N2—C17—C16i	179.26 (16)
C17—N2—C16—C17i	−1.3 (3)	C14—C13—C12—C11	−0.5 (3)
C10—C15—C14—C13	1.6 (3)	C15—C10—C11—C12	−0.6 (3)
N2—C15—C14—C13	−179.86 (17)	C15—C10—C11—C18	178.63 (19)
C7—N1—C6—C5	−126.3 (2)	C13—C12—C11—C10	1.3 (3)
C8—N1—C6—C5	54.1 (2)	C13—C12—C11—C18	−177.93 (19)
C7—N1—C6—C1	56.7 (2)	C1—C6—C5—C4	−0.3 (3)
C8—N1—C6—C1	−122.93 (19)	N1—C6—C5—C4	−177.27 (19)
C6—N1—C7—O1	1.7 (3)	C6—C5—C4—C3	1.1 (3)
C8—N1—C7—O1	−178.69 (18)	C6—C1—C2—C3	0.8 (3)
C6—N1—C7—C8ii	−177.35 (17)	C6—C1—C2—C9	−178.7 (2)
C8—N1—C7—C8ii	2.2 (3)	C5—C4—C3—C2	−0.9 (4)
C5—C6—C1—C2	−0.7 (3)	C1—C2—C3—C4	0.0 (3)
N1—C6—C1—C2	176.35 (17)	C9—C2—C3—C4	179.4 (2)

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8B···O1iii	0.97	2.53	3.494 (2)	173
C14—H14A···O2iii	0.93	2.45	3.325 (3)	158

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C8—H8B⋯O1i	0.97	2.53	3.494 (2)	173
C14—H14A⋯O2i	0.93	2.45	3.325 (3)	158

Symmetry code: (i) .