An orthorhombic polymorph of 2,3,2',3'-tetrakis(2-pyridyl)-6,6'-biquinoxalinyl

When recrystallized from a water-methanol solution, the title compound, C₃₆H₂₂N₈, gave orthorhombic crystals in the non-centrosymmetric space group Fdd2. The mol­ecules are located on twofold rotation axes. The dihedral angle between the approximately planar quinoxaline moieties is 32.93 (4)°. The two pyridine substituents lie out of the plane of the quinoxaline moiety by 56.6 (2) and 33.5 (2)°, and are inclined to one another by 50.2 (2)°. Their N atoms are directed on opposite sides of the mean plane through the quinoxaline moiety.

Key indicators

• Single-crystal X-ray study
• T = 223 K
• R factor = 0.036
• wR factor = 0.087
• Data-to-parameter ratio = 7.0

checkCIF/PLATON results

No syntax errors found



Alert level C
GOODF01_ALERT_2_C  The least squares goodness of fit parameter lies
            outside the range 0.80 <> 2.00
            Goodness of fit given =      0.700
RINTA01_ALERT_3_C  The value of Rint is greater than 0.10
            Rint given   0.107
PLAT020_ALERT_3_C The value of Rint is greater than 0.10 .........       0.11
PLAT089_ALERT_3_C Poor Data / Parameter Ratio (Zmax .LT. 18) .....       7.02
PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          6
PLAT482_ALERT_4_C Small D-H..A Angle Rep for C12    ..  N2       =      95.00 Deg.

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           25.87
           From the CIF: _reflns_number_total               1396
           Count of symmetry unique reflns         1400
           Completeness (_total/calc)             99.71%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   6 ALERT level C = Check and explain
   1 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
   4 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: EXPOSE (Stoe, 2000); cell refinement: CELL (Stoe, 2000); data reduction: INTEGRATE (Stoe, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON99 (Spek, 1990); software used to prepare material for publication: SHELXL97.

2,3,2',3'-tetrakis(2-pyridyl)-6,6'-biquinoxalinyl

Crystal data

C36H22N8	F(000) = 2352
Mr = 566.62	Dx = 1.365 Mg m^−3
Orthorhombic, Fdd2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: F 2 -2d	Cell parameters from 3165 reflections
a = 21.0806 (19) Å	θ = 2.3–25.9°
b = 20.338 (2) Å	µ = 0.09 mm^−1
c = 12.8637 (13) Å	T = 223 K
V = 5515.1 (9) Å^3	Plate, orange
Z = 8	0.50 × 0.40 × 0.10 mm

Data collection

STOE IPDS diffractometer	775 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.107
Graphite monochromator	θmax = 25.9°, θmin = 2.1°
Detector resolution: 0.81Å pixels mm^-1	h = −25→25
φ scans	k = −24→24
10285 measured reflections	l = −15→15
1396 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.087	H-atom parameters constrained
S = 0.70	w = 1/[σ^2(Fo^2) + (0.0536P)^2] where P = (Fo^2 + 2Fc^2)/3
1396 reflections	(Δ/σ)max < 0.001
199 parameters	Δρmax = 0.19 e Å^−3
1 restraint	Δρmin = −0.22 e Å^−3

Special details

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
N1	−0.01572 (14)	0.20621 (14)	0.2296 (3)	0.0290 (7)
N2	0.11384 (14)	0.21140 (14)	0.2856 (3)	0.0298 (8)
N3	0.01067 (15)	0.34657 (15)	0.0966 (3)	0.0362 (9)
N4	0.08752 (16)	0.38174 (16)	0.2835 (2)	0.0356 (9)
C1	0.01664 (19)	0.03190 (18)	0.2792 (3)	0.0273 (9)
C2	−0.01511 (19)	0.08967 (18)	0.2564 (3)	0.0289 (9)
H2	−0.0585	0.0883	0.2396	0.035*
C3	0.01661 (17)	0.15041 (17)	0.2579 (3)	0.0254 (9)
C4	0.01714 (18)	0.26157 (17)	0.2257 (3)	0.0280 (9)
C5	−0.01744 (18)	0.31889 (17)	0.1796 (3)	0.0287 (9)
C6	−0.0759 (2)	0.33895 (19)	0.2186 (3)	0.0341 (10)
H6	−0.0945	0.3172	0.2754	0.041*
C7	−0.10575 (19)	0.39162 (19)	0.1717 (3)	0.0374 (11)
H7	−0.1447	0.4072	0.1974	0.045*
C8	−0.0776 (2)	0.4212 (2)	0.0865 (4)	0.0432 (11)
H8	−0.0974	0.4567	0.0527	0.052*
C9	−0.0195 (2)	0.3972 (2)	0.0520 (3)	0.0448 (12)
H9	−0.0003	0.4177	−0.0056	0.054*
C10	0.08254 (19)	0.26459 (18)	0.2577 (3)	0.0293 (10)
C11	0.11939 (19)	0.32701 (19)	0.2577 (3)	0.0315 (10)
C12	0.18287 (19)	0.3267 (2)	0.2299 (3)	0.0377 (11)
H12	0.2037	0.2870	0.2147	0.045*
C13	0.2151 (2)	0.3861 (2)	0.2248 (4)	0.0478 (12)
H13	0.2579	0.3876	0.2046	0.057*
C14	0.1829 (2)	0.4427 (2)	0.2499 (3)	0.0450 (13)
H14	0.2035	0.4836	0.2472	0.054*
C15	0.1203 (2)	0.4387 (2)	0.2791 (3)	0.0435 (11)
H15	0.0992	0.4778	0.2970	0.052*
C16	0.08131 (19)	0.15310 (18)	0.2834 (3)	0.0277 (9)
C17	0.1136 (2)	0.09398 (18)	0.3085 (3)	0.0318 (10)
H17	0.1566	0.0951	0.3276	0.038*
C18	0.08208 (19)	0.03590 (18)	0.3047 (3)	0.0307 (10)
H18	0.1043	−0.0031	0.3194	0.037*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0296 (18)	0.0222 (17)	0.0354 (18)	−0.0018 (15)	−0.0036 (16)	0.0006 (14)
N2	0.0280 (19)	0.0251 (17)	0.0363 (19)	−0.0010 (16)	−0.0037 (16)	0.0010 (16)
N3	0.042 (2)	0.033 (2)	0.033 (2)	0.0074 (16)	0.0032 (17)	0.0043 (16)
N4	0.044 (2)	0.0287 (19)	0.034 (2)	−0.0014 (16)	−0.0010 (17)	−0.0014 (16)
C1	0.032 (2)	0.025 (2)	0.025 (2)	−0.0014 (17)	−0.0011 (18)	0.0013 (17)
C2	0.027 (2)	0.027 (2)	0.032 (2)	0.0003 (18)	−0.0051 (19)	0.0026 (18)
C3	0.026 (2)	0.020 (2)	0.031 (2)	0.0013 (17)	−0.0017 (19)	0.0018 (17)
C4	0.030 (2)	0.026 (2)	0.028 (2)	−0.0002 (17)	−0.0019 (19)	0.0010 (17)
C5	0.034 (2)	0.0200 (19)	0.032 (2)	0.0004 (18)	−0.0044 (19)	−0.0023 (17)
C6	0.040 (3)	0.026 (2)	0.036 (2)	−0.004 (2)	−0.003 (2)	−0.0007 (17)
C7	0.030 (2)	0.033 (2)	0.049 (3)	0.0082 (19)	−0.005 (2)	−0.006 (2)
C8	0.050 (3)	0.031 (2)	0.048 (3)	0.015 (2)	−0.008 (2)	0.003 (2)
C9	0.056 (3)	0.038 (3)	0.040 (3)	0.009 (2)	0.001 (2)	0.011 (2)
C10	0.034 (2)	0.025 (2)	0.028 (2)	−0.0004 (18)	−0.0025 (19)	−0.0019 (17)
C11	0.036 (2)	0.024 (2)	0.035 (2)	−0.0043 (18)	−0.006 (2)	−0.0017 (18)
C12	0.030 (3)	0.033 (2)	0.050 (3)	0.0002 (19)	−0.010 (2)	−0.002 (2)
C13	0.040 (3)	0.051 (3)	0.052 (3)	−0.016 (2)	−0.011 (2)	0.005 (2)
C14	0.059 (4)	0.036 (3)	0.040 (3)	−0.016 (2)	−0.012 (2)	0.000 (2)
C15	0.061 (3)	0.026 (2)	0.044 (3)	−0.003 (2)	0.000 (2)	−0.004 (2)
C16	0.028 (2)	0.022 (2)	0.033 (2)	0.0014 (17)	−0.0021 (18)	0.0016 (18)
C17	0.027 (2)	0.032 (2)	0.037 (3)	−0.0004 (18)	−0.0028 (19)	0.001 (2)
C18	0.032 (2)	0.023 (2)	0.037 (3)	0.0051 (18)	−0.0040 (19)	0.0024 (18)

Geometric parameters (Å, º)

N1—C4	1.323 (5)	C7—C8	1.383 (6)
N1—C3	1.373 (4)	C7—H7	0.9400
N2—C10	1.317 (5)	C8—C9	1.392 (6)
N2—C16	1.370 (5)	C8—H8	0.9400
N3—C9	1.340 (5)	C9—H9	0.9400
N3—C5	1.344 (5)	C10—C11	1.488 (5)
N4—C11	1.342 (5)	C11—C12	1.385 (5)
N4—C15	1.351 (5)	C12—C13	1.387 (6)
C1—C2	1.384 (5)	C12—H12	0.9400
C1—C18	1.420 (5)	C13—C14	1.374 (6)
C1—C1^i	1.475 (7)	C13—H13	0.9400
C2—C3	1.405 (5)	C14—C15	1.374 (6)
C2—H2	0.9400	C14—H14	0.9400
C3—C16	1.404 (5)	C15—H15	0.9400
C4—C10	1.440 (5)	C16—C17	1.419 (5)
C4—C5	1.497 (5)	C17—C18	1.356 (5)
C5—C6	1.391 (5)	C17—H17	0.9400
C6—C7	1.381 (6)	C18—H18	0.9400
C6—H6	0.9400
C4—N1—C3	117.0 (3)	N3—C9—H9	118.3
C10—N2—C16	117.0 (3)	C8—C9—H9	118.3
C9—N3—C5	116.9 (3)	N2—C10—C4	121.5 (3)
C11—N4—C15	116.4 (4)	N2—C10—C11	116.1 (4)
C2—C1—C18	118.0 (4)	C4—C10—C11	122.4 (3)
C2—C1—C1^i	121.1 (5)	N4—C11—C12	123.4 (4)
C18—C1—C1^i	120.8 (4)	N4—C11—C10	116.5 (4)
C1—C2—C3	120.9 (4)	C12—C11—C10	120.0 (4)
C1—C2—H2	119.6	C11—C12—C13	118.8 (4)
C3—C2—H2	119.6	C11—C12—H12	120.6
N1—C3—C2	119.1 (3)	C13—C12—H12	120.6
N1—C3—C16	120.8 (3)	C14—C13—C12	118.4 (4)
C2—C3—C16	120.0 (3)	C14—C13—H13	120.8
N1—C4—C10	121.8 (3)	C12—C13—H13	120.8
N1—C4—C5	115.0 (3)	C15—C14—C13	119.3 (4)
C10—C4—C5	123.1 (3)	C15—C14—H14	120.4
N3—C5—C6	123.6 (3)	C13—C14—H14	120.4
N3—C5—C4	115.2 (3)	N4—C15—C14	123.6 (4)
C6—C5—C4	121.1 (3)	N4—C15—H15	118.2
C7—C6—C5	118.3 (4)	C14—C15—H15	118.2
C7—C6—H6	120.9	N2—C16—C3	121.7 (3)
C5—C6—H6	120.9	N2—C16—C17	119.2 (4)
C6—C7—C8	119.2 (4)	C3—C16—C17	119.1 (3)
C6—C7—H7	120.4	C18—C17—C16	119.7 (4)
C8—C7—H7	120.4	C18—C17—H17	120.2
C9—C8—C7	118.6 (4)	C16—C17—H17	120.2
C9—C8—H8	120.7	C17—C18—C1	122.3 (4)
C7—C8—H8	120.7	C17—C18—H18	118.9
N3—C9—C8	123.4 (4)	C1—C18—H18	118.9
C18—C1—C2—C3	0.3 (6)	C5—C4—C10—C11	6.4 (6)
C1^i—C1—C2—C3	179.1 (3)	C15—N4—C11—C12	1.4 (6)
C4—N1—C3—C2	−175.7 (4)	C15—N4—C11—C10	−177.3 (4)
C4—N1—C3—C16	1.4 (6)	N2—C10—C11—N4	−146.3 (4)
C1—C2—C3—N1	176.7 (4)	C4—C10—C11—N4	35.9 (5)
C1—C2—C3—C16	−0.4 (6)	N2—C10—C11—C12	35.0 (5)
C3—N1—C4—C10	−5.0 (6)	C4—C10—C11—C12	−142.8 (4)
C3—N1—C4—C5	171.3 (3)	N4—C11—C12—C13	−2.2 (6)
C9—N3—C5—C6	1.7 (5)	C10—C11—C12—C13	176.4 (4)
C9—N3—C5—C4	178.8 (3)	C11—C12—C13—C14	1.4 (7)
N1—C4—C5—N3	−122.3 (4)	C12—C13—C14—C15	0.0 (7)
C10—C4—C5—N3	54.1 (5)	C11—N4—C15—C14	0.2 (6)
N1—C4—C5—C6	54.9 (5)	C13—C14—C15—N4	−0.9 (7)
C10—C4—C5—C6	−128.8 (4)	C10—N2—C16—C3	−3.3 (5)
N3—C5—C6—C7	−2.2 (5)	C10—N2—C16—C17	177.3 (4)
C4—C5—C6—C7	−179.1 (4)	N1—C3—C16—N2	3.0 (6)
C5—C6—C7—C8	1.8 (6)	C2—C3—C16—N2	−180.0 (4)
C6—C7—C8—C9	−1.0 (6)	N1—C3—C16—C17	−177.7 (4)
C5—N3—C9—C8	−0.8 (6)	C2—C3—C16—C17	−0.7 (6)
C7—C8—C9—N3	0.5 (7)	N2—C16—C17—C18	−178.9 (4)
C16—N2—C10—C4	−0.3 (5)	C3—C16—C17—C18	1.8 (6)
C16—N2—C10—C11	−178.2 (4)	C16—C17—C18—C1	−2.0 (6)
N1—C4—C10—N2	4.8 (6)	C2—C1—C18—C17	0.9 (6)
C5—C4—C10—N2	−171.3 (3)	C1^i—C1—C18—C17	−177.9 (3)
N1—C4—C10—C11	−177.5 (4)

Symmetry code: (i) −x, −y, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C12—H12···N2	0.94	2.60	2.851 (5)	95