9,9a-Diphenyl-1,3,4,6,7,9a-hexa­hydro-2H-pyrazino[1,2-a]pyrimidine at 130 K

The stereochemistry of the title compound, C₁₉H₂₁N₃, has been confirmed by a single-crystal X-ray analysis. The bicyclic ring system adopts a cis-deca­lin-like conformation, which presumably minimizes steric repulsion involving the bridgehead phenyl substituent. The conformation of the amino group appears to be dictated by a nitro­gen anomeric effect.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.038
• wR factor = 0.101
• Data-to-parameter ratio = 10.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT088_ALERT_3_C Poor Data / Parameter Ratio ....................       9.98
PLAT230_ALERT_2_C Hirshfeld Test Diff for    C20    -   C21     ..       6.40 su

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 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
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 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: SMART (Bruker, 2000); cell refinement: SAINT (Bruker 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000); software used to prepare material for publication: WinGX (Farrugia, 1999).

9,9a-Diphenyl-1,3,4,6,7,9a-hexahydro-2H-pyrazino[1,2-a]pyrimidine

Crystal data

C19H21N3	F(000) = 624
Mr = 291.39	Dx = 1.206 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3216 reflections
a = 10.4099 (7) Å	θ = 2.5–27.0°
b = 8.2868 (6) Å	µ = 0.07 mm^−1
c = 19.1371 (14) Å	T = 295 K
β = 103.483 (1)°	Block, colourless
V = 1605.4 (2) Å^3	0.50 × 0.40 × 0.30 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer	2259 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.059
Graphite monochromator	θmax = 25.0°, θmin = 2.0°
φ and ω scans	h = −9→12
8199 measured reflections	k = −9→9
2833 independent reflections	l = −22→18

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)] = 0.039	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.102	w = 1/[σ^2(Fo^2) + (0.0552P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max = 0.002
2833 reflections	Δρmax = 0.16 e Å^−3
284 parameters	Δρmin = −0.14 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0091 (18)

Special details

Experimental. Spectroscopic analysis: ¹H NMR (CDCl₃, δ, p.p.m.): 7.58 (d, 2H, J = 7.8 Hz), 7.3–7.04 (m, 8H), 4.10–3.80 (m, 2H), 3.27 (m, 1H), 3.00 (m, 2H), 2.76 (m, 3H), 2.34 (bs, 1H), 1.83 (m, 1H), 1.27 (m, 1H); ¹³C NMR (δ, p.p.m.): 170.14, 140.87, 139.55, 128.93, 128.27, 127.98, 127.56, 127.10, 75.96, 48.74, 48.56, 43.57, 40.63, 21.53.

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 (Ų)

	x	y	z	Uiso*/Ueq
C1	0.76592 (11)	0.56603 (14)	0.16106 (6)	0.0376 (3)
C2	0.87028 (12)	0.66449 (14)	0.21485 (6)	0.0384 (3)
C4	1.01466 (16)	0.6782 (2)	0.13673 (9)	0.0576 (4)
C5	0.94319 (14)	0.53347 (18)	0.10020 (8)	0.0496 (4)
C7	0.72076 (16)	0.44324 (19)	0.04279 (8)	0.0550 (4)
C8	0.72399 (18)	0.27596 (19)	0.07505 (8)	0.0603 (4)
C9	0.68490 (16)	0.28547 (19)	0.14644 (8)	0.0547 (4)
C11	0.63407 (11)	0.65710 (16)	0.15083 (6)	0.0407 (3)
C12	0.61311 (14)	0.79593 (17)	0.10884 (7)	0.0508 (4)
C13	0.50115 (15)	0.8888 (2)	0.10474 (9)	0.0624 (4)
C14	0.40845 (16)	0.8451 (2)	0.14178 (9)	0.0667 (5)
C15	0.42783 (15)	0.7082 (2)	0.18299 (9)	0.0630 (4)
C16	0.54028 (13)	0.61408 (19)	0.18793 (8)	0.0507 (4)
C17	0.84523 (12)	0.69133 (14)	0.28802 (6)	0.0399 (3)
C18	0.92079 (16)	0.60477 (18)	0.34463 (8)	0.0570 (4)
C19	0.9021 (2)	0.6243 (2)	0.41337 (9)	0.0719 (5)
C20	0.80995 (18)	0.7298 (2)	0.42663 (9)	0.0670 (5)
C21	0.73585 (15)	0.8181 (2)	0.37137 (8)	0.0617 (4)
C22	0.75340 (14)	0.79933 (18)	0.30254 (8)	0.0522 (4)
N3	0.97892 (11)	0.71750 (13)	0.20461 (6)	0.0489 (3)
N6	0.80224 (10)	0.56136 (13)	0.09106 (5)	0.0429 (3)
N10	0.75858 (11)	0.40874 (13)	0.19501 (5)	0.0420 (3)
H4A	0.9946 (15)	0.773 (2)	0.1041 (9)	0.074 (5)*
H4B	1.1098 (17)	0.666 (2)	0.1470 (8)	0.073 (5)*
H5A	0.9634 (13)	0.5249 (17)	0.0527 (8)	0.057 (4)*
H5B	0.9756 (12)	0.4346 (18)	0.1298 (7)	0.053 (4)*
H7A	0.6302 (15)	0.4812 (17)	0.0306 (7)	0.057 (4)*
H7B	0.7541 (13)	0.4425 (17)	−0.0036 (8)	0.056 (4)*
H8A	0.6652 (16)	0.207 (2)	0.0436 (9)	0.075 (5)*
H8B	0.8146 (16)	0.2289 (19)	0.0836 (8)	0.066 (4)*
H9A	0.5883 (15)	0.3142 (17)	0.1382 (7)	0.057 (4)*
H9B	0.7010 (14)	0.180 (2)	0.1716 (8)	0.065 (4)*
H10	0.8396 (14)	0.3702 (16)	0.2135 (7)	0.048 (4)*
H12	0.6774 (14)	0.8249 (17)	0.0812 (7)	0.056 (4)*
H13	0.4914 (15)	0.982 (2)	0.0743 (8)	0.067 (5)*
H14	0.3318 (16)	0.915 (2)	0.1391 (8)	0.072 (5)*
H15	0.3665 (16)	0.6776 (19)	0.2107 (8)	0.070 (5)*
H16	0.5542 (13)	0.5221 (18)	0.2191 (7)	0.056 (4)*
H18	0.9894 (16)	0.531 (2)	0.3336 (8)	0.069 (5)*
H19	0.9564 (19)	0.566 (2)	0.4505 (11)	0.099 (6)*
H20	0.7942 (15)	0.7411 (19)	0.4734 (8)	0.072 (5)*
H21	0.6734 (17)	0.896 (2)	0.3825 (9)	0.082 (5)*
H22	0.6993 (15)	0.863 (2)	0.2628 (9)	0.073 (5)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0396 (7)	0.0396 (7)	0.0336 (7)	−0.0002 (5)	0.0087 (5)	0.0004 (5)
C2	0.0397 (7)	0.0331 (6)	0.0410 (7)	0.0027 (5)	0.0066 (5)	0.0028 (5)
C4	0.0523 (9)	0.0584 (10)	0.0694 (10)	−0.0086 (7)	0.0291 (8)	−0.0060 (8)
C5	0.0524 (8)	0.0523 (9)	0.0494 (9)	0.0035 (7)	0.0227 (6)	−0.0010 (7)
C7	0.0600 (10)	0.0653 (10)	0.0378 (8)	−0.0008 (7)	0.0075 (7)	−0.0086 (7)
C8	0.0683 (11)	0.0549 (9)	0.0553 (9)	−0.0130 (8)	0.0098 (8)	−0.0173 (7)
C9	0.0610 (10)	0.0470 (9)	0.0556 (9)	−0.0126 (7)	0.0125 (7)	−0.0078 (7)
C11	0.0387 (7)	0.0469 (8)	0.0345 (7)	−0.0002 (6)	0.0046 (5)	−0.0052 (5)
C12	0.0508 (8)	0.0536 (9)	0.0462 (8)	0.0053 (6)	0.0079 (6)	0.0014 (6)
C13	0.0641 (10)	0.0549 (10)	0.0611 (10)	0.0152 (8)	0.0005 (8)	0.0008 (8)
C14	0.0489 (9)	0.0717 (11)	0.0741 (11)	0.0161 (8)	0.0036 (8)	−0.0149 (9)
C15	0.0440 (9)	0.0788 (12)	0.0684 (10)	0.0003 (8)	0.0178 (7)	−0.0117 (9)
C16	0.0442 (8)	0.0585 (9)	0.0492 (8)	−0.0001 (6)	0.0102 (6)	−0.0030 (7)
C17	0.0421 (7)	0.0368 (7)	0.0381 (7)	−0.0067 (5)	0.0039 (5)	−0.0029 (5)
C18	0.0755 (10)	0.0446 (8)	0.0457 (9)	0.0070 (7)	0.0036 (7)	0.0013 (6)
C19	0.1125 (14)	0.0542 (10)	0.0414 (9)	0.0019 (10)	0.0028 (9)	0.0073 (7)
C20	0.0933 (13)	0.0671 (11)	0.0443 (9)	−0.0211 (9)	0.0235 (9)	−0.0121 (8)
C21	0.0581 (9)	0.0770 (11)	0.0502 (9)	−0.0025 (8)	0.0130 (7)	−0.0175 (8)
C22	0.0500 (8)	0.0591 (9)	0.0439 (8)	0.0050 (7)	0.0034 (6)	−0.0086 (7)
N3	0.0466 (6)	0.0469 (7)	0.0547 (7)	−0.0070 (5)	0.0151 (5)	−0.0034 (5)
N6	0.0459 (6)	0.0477 (6)	0.0362 (6)	0.0021 (5)	0.0117 (4)	−0.0007 (5)
N10	0.0439 (7)	0.0397 (6)	0.0408 (6)	−0.0033 (5)	0.0066 (5)	0.0003 (5)

Geometric parameters (Å, º)

C1—N10	1.4662 (16)	C11—C16	1.3812 (18)
C1—N6	1.4748 (15)	C11—C12	1.3911 (19)
C1—C11	1.5383 (16)	C12—C13	1.384 (2)
C1—C2	1.5441 (16)	C12—H12	0.975 (14)
C2—N3	1.2703 (15)	C13—C14	1.373 (2)
C2—C17	1.4994 (17)	C13—H13	0.956 (17)
C4—N3	1.4688 (18)	C14—C15	1.369 (2)
C4—C5	1.496 (2)	C14—H14	0.977 (17)
C4—H4A	0.992 (17)	C15—C16	1.391 (2)
C4—H4B	0.969 (16)	C15—H15	0.955 (16)
C5—N6	1.4551 (17)	C16—H16	0.959 (15)
C5—H5A	0.983 (14)	C17—C18	1.3819 (18)
C5—H5B	1.008 (14)	C17—C22	1.3842 (19)
C7—N6	1.4716 (17)	C18—C19	1.384 (2)
C7—C8	1.515 (2)	C18—H18	0.998 (16)
C7—H7A	0.970 (14)	C19—C20	1.365 (3)
C7—H7B	1.025 (15)	C19—H19	0.93 (2)
C8—C9	1.516 (2)	C20—C21	1.367 (2)
C8—H8A	0.945 (17)	C20—H20	0.951 (15)
C8—H8B	0.999 (16)	C21—C22	1.3802 (19)
C9—N10	1.4708 (16)	C21—H21	0.973 (18)
C9—H9A	1.009 (15)	C22—H22	0.987 (17)
C9—H9B	0.992 (16)	N10—H10	0.894 (14)
N10—C1—N6	115.47 (10)	C12—C11—C1	119.64 (11)
N10—C1—C11	110.82 (10)	C13—C12—C11	120.63 (15)
N6—C1—C11	107.90 (9)	C13—C12—H12	120.5 (8)
N10—C1—C2	106.00 (9)	C11—C12—H12	118.8 (8)
N6—C1—C2	109.26 (9)	C14—C13—C12	120.53 (17)
C11—C1—C2	107.09 (9)	C14—C13—H13	122.7 (9)
N3—C2—C17	116.59 (10)	C12—C13—H13	116.8 (9)
N3—C2—C1	126.38 (11)	C15—C14—C13	119.30 (15)
C17—C2—C1	116.90 (10)	C15—C14—H14	121.9 (9)
N3—C4—C5	112.94 (12)	C13—C14—H14	118.7 (9)
N3—C4—H4A	108.9 (9)	C14—C15—C16	120.80 (16)
C5—C4—H4A	109.2 (9)	C14—C15—H15	120.8 (10)
N3—C4—H4B	107.5 (9)	C16—C15—H15	118.4 (10)
C5—C4—H4B	112.7 (10)	C11—C16—C15	120.33 (16)
H4A—C4—H4B	105.3 (13)	C11—C16—H16	120.2 (8)
N6—C5—C4	107.84 (12)	C15—C16—H16	119.4 (8)
N6—C5—H5A	109.2 (8)	C18—C17—C22	118.15 (13)
C4—C5—H5A	107.4 (8)	C18—C17—C2	117.64 (12)
N6—C5—H5B	113.1 (7)	C22—C17—C2	124.19 (11)
C4—C5—H5B	108.9 (8)	C17—C18—C19	120.27 (15)
H5A—C5—H5B	110.2 (11)	C17—C18—H18	117.1 (9)
N6—C7—C8	113.46 (12)	C19—C18—H18	122.7 (9)
N6—C7—H7A	108.7 (8)	C20—C19—C18	120.84 (16)
C8—C7—H7A	108.8 (9)	C20—C19—H19	121.1 (12)
N6—C7—H7B	106.6 (8)	C18—C19—H19	118.0 (12)
C8—C7—H7B	111.6 (8)	C19—C20—C21	119.56 (15)
H7A—C7—H7B	107.5 (11)	C19—C20—H20	121.4 (10)
C7—C8—C9	109.55 (13)	C21—C20—H20	119.0 (10)
C7—C8—H8A	110.2 (10)	C20—C21—C22	120.12 (16)
C9—C8—H8A	109.7 (10)	C20—C21—H21	118.1 (10)
C7—C8—H8B	110.8 (9)	C22—C21—H21	121.8 (10)
C9—C8—H8B	108.4 (9)	C21—C22—C17	121.04 (14)
H8A—C8—H8B	108.3 (13)	C21—C22—H22	119.8 (9)
N10—C9—C8	113.31 (12)	C17—C22—H22	119.2 (9)
N10—C9—H9A	106.8 (8)	C2—N3—C4	118.56 (11)
C8—C9—H9A	109.8 (8)	C5—N6—C7	112.78 (11)
N10—C9—H9B	107.5 (9)	C5—N6—C1	111.09 (10)
C8—C9—H9B	109.9 (8)	C7—N6—C1	110.82 (10)
H9A—C9—H9B	109.4 (12)	C1—N10—C9	114.25 (10)
C16—C11—C12	118.41 (12)	C1—N10—H10	110.5 (9)
C16—C11—C1	121.64 (12)	C9—N10—H10	107.9 (8)
N10—C1—C2—N3	117.10 (13)	C1—C2—C17—C22	−75.05 (16)
N6—C1—C2—N3	−7.93 (16)	C22—C17—C18—C19	1.3 (2)
C11—C1—C2—N3	−124.55 (12)	C2—C17—C18—C19	−179.94 (13)
N10—C1—C2—C17	−58.73 (13)	C17—C18—C19—C20	−0.5 (2)
N6—C1—C2—C17	176.23 (9)	C18—C19—C20—C21	−0.4 (3)
C11—C1—C2—C17	59.62 (13)	C19—C20—C21—C22	0.6 (2)
N3—C4—C5—N6	54.85 (17)	C20—C21—C22—C17	0.2 (2)
N6—C7—C8—C9	54.90 (18)	C18—C17—C22—C21	−1.2 (2)
C7—C8—C9—N10	−50.40 (19)	C2—C17—C22—C21	−179.82 (12)
N10—C1—C11—C16	17.31 (15)	C17—C2—N3—C4	173.19 (12)
N6—C1—C11—C16	144.62 (11)	C1—C2—N3—C4	−2.66 (18)
C2—C1—C11—C16	−97.86 (13)	C5—C4—N3—C2	−20.98 (19)
N10—C1—C11—C12	−169.18 (11)	C4—C5—N6—C7	168.15 (12)
N6—C1—C11—C12	−41.87 (14)	C4—C5—N6—C1	−66.74 (14)
C2—C1—C11—C12	75.65 (13)	C8—C7—N6—C5	71.06 (16)
C16—C11—C12—C13	0.29 (19)	C8—C7—N6—C1	−54.19 (16)
C1—C11—C12—C13	−173.42 (12)	N10—C1—N6—C5	−76.69 (13)
C11—C12—C13—C14	−0.3 (2)	C11—C1—N6—C5	158.74 (10)
C12—C13—C14—C15	0.0 (2)	C2—C1—N6—C5	42.64 (12)
C13—C14—C15—C16	0.3 (2)	N10—C1—N6—C7	49.52 (13)
C12—C11—C16—C15	0.06 (19)	C11—C1—N6—C7	−75.06 (12)
C1—C11—C16—C15	173.64 (12)	C2—C1—N6—C7	168.85 (10)
C14—C15—C16—C11	−0.4 (2)	N6—C1—N10—C9	−46.89 (15)
N3—C2—C17—C18	−69.94 (15)	C11—C1—N10—C9	76.15 (13)
C1—C2—C17—C18	106.31 (13)	C2—C1—N10—C9	−168.01 (11)
N3—C2—C17—C22	108.70 (15)	C8—C9—N10—C1	47.26 (18)