A large delocalized π-electron system: diquinoxalino­[2,3-a:2′,3′-c]­phenazine chloro­form solvate

The title compound, C₂₄H₁₂N₆·CHCl₃, crystallizes in the monoclinic system in space group P2₁/c. The structure consists of one mol­ecule of diquinoxalino­[2,3-a:2′,3′-c]­phenazine (Dqpz), which is a large delocalized π-electron system, and a chloro­form solvent mol­ecule. There exist weak intermolecular C—H...N and π–π interactions between adjacent Dqpz mol­ecules.

S1. Comment

Bridging ligands providing three bidentate metal-binding sites, such as 1,4,5,8,9,12-hexaazatriphenylene (Hat) (Moucheron et al., 1996; Baxter et al., 1997), are particularly promising as building blocks for the construction of multidimensional structures because they provide robust networks with good electronic communication between the metal centers. Much pioneering work in this field has been done by Robson and co-workers (Batten et al., 1998; Abrahams et al., 1999). In our efforts to construct novel extended multi-dimensional networks, the compound, diquinoxalino[2,3 - a:2*,3*-c]phenazine, (I), attracts our attention. This compound has a very similar backbone and coordination sites with Hat. But it has a bigger delocalized π-electron system than Hat which may provide more facile electronic communication between attached metal centres. The crystal structure of the title compound is the focus of our present report. \sch

The structure of (I) comprises the diquinoxalino[2,3 - a:2*,3*-c]phenazine and a chloroform molecule in the crystal lattice. A perspective view of (I) including the atomic numbering scheme is shown in Fig. 1. In the central C₆ ring, the maximum deviation of any atoms from the best-fit plane is 0.0106 (1) Å, while the average deviation is 0.0068 (2) Å. Furthermore, all non-hydrogen atoms lie roughly in a plane: the mean deviation of any non-H atoms in Dqpz from the best-fit plane describing them is 0.1282 (4) Å, forming a dihedral angle of 2.30 (2)° with the central C₆ring. The distortions from planarity should have a noticeable effect on the electronic communication provided by this bridging ligand. The main molecule has a C₃ symmetry and the bond distances and angles are quite similar in three different directions. The C—N bond distances lie in the range of 1.323 (3)–1.363 (3) Å, which are remarkable shorter than normal C—N single bond (1.47 Å) (Sasada et al., 1984) and longer than the value of C—N double bond distance (1.28 Å) (Wang et al., 1998) due to the π-electron repulsion of the bulky system. The C—C bond distances are in the range 1.351 (4)–1.483 (3) Å and all the bond angles are about 120°, falling within normal limits. All the features mentioned above indicate that Dqpz molecule has a very large delocalized π-electron system which may provide facile electronic communication. [Weak intermolecular interaction exists between C44—H44···N22 with C···N nonbond separation of 3.355 (4) Å and C—H···N angle of 141.0 (3)°]. The chloroform molecule also donates C—H···N hydrogen bonds to Dqpz (C1—H1···N31 and C1—H1···N41) with C···N separations of 3.256 (3) and 3.330 (4) and bond angles of 145.4 (2) and 143.6 (14)°. In addition, there are π···π stacks of parallel molecules along the b axis with an interplanar spacing of 3.481 (2) Å which stabilize the crystal (Fig. 2).

Related literature

For related literature, see: Abrahams et al. (1999); Batten & Robson (1998); Baxter et al. (1997); Moucheron & Mesmaeker (1996); Sasada (1984); Skujins & Webb (1969); Wang et al. (1998).

S2. Experimental

The title compound was synthesized by stirring hexaketocyclohexane octahydrate (0.50 g, 1.6 mmol) and 1,2-phenylenediamine (0.52 g, 4.8 mmol) in the presence of several drops of acetic acid in ethanol solution (50 ml) at room temperature for 2 h. The solvent was concentrated in vacuo to afford colorless solid which was purified by recrystallization from CH₂Cl₂/CH₃OH to obtain the single crystals suitable for X-ray diffraction. The product was characterized by NMR and mass spectrometry, giving results consistent with those in the literature (Skujins et al., 1969).

S3. Refinement

H atoms were located by geometry and take part in the structure factor calculations.

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Sheldrick, 1997).

Figures

	Fig. 1. ORTEPII (Johnson, 1976) view of the title compound with 30% probability.
	Fig. 2. Molecular packing diagram in the unit cell of the title compound.

Diquinoxalino[2,3 - a:2*,3*-c]phenazine chloroform

Crystal data

C24N6H12·CHCl3	F(000) = 1024
Mr = 503.76	Dx = 1.565 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 19.5061 (19) Å	Cell parameters from 10967 reflections
b = 5.3820 (5) Å	θ = 2.0–27.9°
c = 20.976 (2) Å	µ = 0.46 mm^−1
β = 103.897 (2)°	T = 193 K
V = 2137.7 (4) Å^3	Prism, colorless
Z = 4	0.15 × 0.15 × 0.15 mm

Data collection

Siemens CCD X-ray diffractometer	1991 reflections with I > 2.0σ(I)
ω scans	Rint = 0.062
Absorption correction: integration (North et al., 1968)	θmax = 27.9°
Tmin = 0.736, Tmax = 0.935	h = −25→14
11035 measured reflections	k = −6→7
4988 independent reflections	l = −26→27

Refinement

Refinement on F^2	w = 1/[σ^2(Fo^2) + (0.0294P)^2] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.047	(Δ/σ)max = 0.016
wR(F^2) = 0.093	Δρmax = 0.29 e Å^−3
S = 0.81	Δρmin = −0.39 e Å^−3
4988 reflections	Extinction correction: SHELXL
307 parameters	Extinction coefficient: none
H-atom parameters constrained

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. Full-MATRIX

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C1	0.08673 (16)	0.3004 (5)	0.16002 (15)	0.0416 (8)
C11	0.34734 (14)	1.0470 (5)	0.27639 (13)	0.0234 (7)
C12	0.31673 (14)	1.0649 (5)	0.33152 (13)	0.0258 (7)
C13	0.26202 (13)	0.8850 (5)	0.33840 (13)	0.0237 (6)
C14	0.23973 (14)	0.6941 (5)	0.29059 (13)	0.0260 (7)
C15	0.27072 (14)	0.6808 (5)	0.23266 (13)	0.0262 (7)
C16	0.32331 (14)	0.8541 (5)	0.22615 (12)	0.0244 (7)
C21	0.42143 (14)	1.3692 (5)	0.31644 (13)	0.0269 (7)
C22	0.39075 (14)	1.3875 (5)	0.37131 (13)	0.0264 (7)
C23	0.41616 (15)	1.5693 (5)	0.41980 (14)	0.0358 (8)
C24	0.46966 (16)	1.7219 (5)	0.41387 (14)	0.0396 (8)
C25	0.50065 (15)	1.7006 (6)	0.36006 (15)	0.0380 (8)
C26	0.47744 (14)	1.5303 (5)	0.31240 (14)	0.0318 (8)
C31	0.16644 (14)	0.5388 (5)	0.35126 (14)	0.0285 (7)
C32	0.18800 (14)	0.7285 (5)	0.39822 (14)	0.0301 (7)
C33	0.15949 (15)	0.7380 (5)	0.45420 (14)	0.0352 (8)
C34	0.11209 (16)	0.5653 (6)	0.46233 (14)	0.0393 (8)
C35	0.09150 (15)	0.3718 (6)	0.41647 (14)	0.0381 (8)
C36	0.11796 (14)	0.3578 (5)	0.36193 (14)	0.0344 (8)
C41	0.27983 (15)	0.4879 (5)	0.13784 (13)	0.0296 (7)
C42	0.33183 (14)	0.6641 (5)	0.13051 (13)	0.0281 (7)
C43	0.36117 (15)	0.6520 (6)	0.07533 (13)	0.0356 (8)
C44	0.34001 (16)	0.4700 (6)	0.03003 (14)	0.0374 (8)
C45	0.28956 (15)	0.2933 (5)	0.03687 (14)	0.0358 (8)
C46	0.25945 (15)	0.3001 (5)	0.08959 (14)	0.0355 (8)
N21	0.39870 (11)	1.1967 (4)	0.26873 (11)	0.0275 (6)
N22	0.33764 (12)	1.2331 (4)	0.37813 (11)	0.0283 (6)
N31	0.19245 (11)	0.5239 (4)	0.29684 (10)	0.0277 (6)
N32	0.23610 (12)	0.9038 (4)	0.39124 (10)	0.0300 (6)
N41	0.24902 (11)	0.4985 (4)	0.18952 (11)	0.0289 (6)
N42	0.35316 (11)	0.8471 (4)	0.17550 (11)	0.0308 (6)
Cl1	0.01552 (4)	0.37462 (17)	0.19364 (4)	0.0559 (3)
Cl2	0.06941 (5)	0.39668 (17)	0.07751 (4)	0.0579 (3)
Cl3	0.10451 (5)	−0.01777 (17)	0.16619 (6)	0.0820 (4)
H1	0.1294	0.3913	0.1853	0.050*
H23	0.3958	1.5846	0.4565	0.043*
H24	0.4864	1.8446	0.4464	0.048*
H25	0.5385	1.8077	0.3572	0.046*
H26	0.4987	1.5189	0.2763	0.038*
H33	0.1737	0.8655	0.4860	0.042*
H34	0.0923	0.5744	0.4995	0.047*
H35	0.0589	0.2499	0.4236	0.046*
H36	0.1038	0.2268	0.3313	0.041*
H43	0.3955	0.7703	0.0699	0.043*
H44	0.3599	0.4623	−0.0071	0.045*
H45	0.2760	0.1672	0.0046	0.043*
H46	0.2252	0.1798	0.0938	0.043*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.045 (2)	0.034 (2)	0.046 (2)	−0.0009 (16)	0.0102 (17)	−0.0011 (16)
C11	0.0206 (16)	0.0240 (18)	0.0242 (16)	0.0024 (13)	0.0023 (13)	0.0040 (13)
C12	0.0257 (17)	0.0283 (19)	0.0246 (16)	0.0032 (14)	0.0087 (14)	0.0034 (14)
C13	0.0214 (16)	0.0275 (17)	0.0222 (15)	0.0017 (14)	0.0054 (13)	0.0026 (15)
C14	0.0265 (17)	0.0281 (19)	0.0228 (16)	0.0033 (14)	0.0048 (14)	0.0053 (14)
C15	0.0224 (16)	0.0302 (19)	0.0254 (16)	0.0061 (14)	0.0046 (14)	0.0000 (14)
C16	0.0255 (16)	0.0271 (18)	0.0209 (15)	0.0033 (14)	0.0060 (14)	0.0019 (14)
C21	0.0249 (17)	0.0272 (17)	0.0280 (16)	0.0052 (15)	0.0054 (14)	0.0019 (15)
C22	0.0233 (16)	0.0275 (18)	0.0278 (16)	0.0019 (15)	0.0051 (14)	0.0055 (16)
C23	0.042 (2)	0.037 (2)	0.0301 (18)	−0.0068 (16)	0.0119 (16)	−0.0058 (16)
C24	0.043 (2)	0.037 (2)	0.036 (2)	−0.0098 (17)	0.0049 (17)	−0.0081 (16)
C25	0.0296 (18)	0.038 (2)	0.046 (2)	−0.0086 (15)	0.0092 (17)	0.0019 (17)
C26	0.0276 (17)	0.036 (2)	0.0350 (18)	−0.0038 (15)	0.0132 (15)	−0.0004 (16)
C31	0.0220 (17)	0.032 (2)	0.0318 (18)	0.0019 (14)	0.0075 (15)	0.0031 (15)
C32	0.0286 (18)	0.0338 (19)	0.0289 (17)	−0.0015 (15)	0.0087 (15)	0.0054 (15)
C33	0.040 (2)	0.038 (2)	0.0298 (18)	−0.0065 (16)	0.0136 (16)	0.0003 (15)
C34	0.041 (2)	0.048 (2)	0.0339 (19)	0.0001 (18)	0.0191 (16)	0.0075 (18)
C35	0.0356 (19)	0.036 (2)	0.043 (2)	−0.0074 (16)	0.0101 (17)	0.0070 (18)
C36	0.0354 (19)	0.0332 (19)	0.0347 (18)	−0.0034 (16)	0.0087 (16)	0.0031 (16)
C41	0.0301 (18)	0.0341 (19)	0.0234 (17)	0.0070 (15)	0.0041 (15)	0.0015 (15)
C42	0.0319 (18)	0.0302 (19)	0.0212 (16)	0.0067 (15)	0.0045 (15)	0.0023 (15)
C43	0.0351 (19)	0.045 (2)	0.0288 (17)	0.0018 (16)	0.0119 (16)	0.0026 (17)
C44	0.040 (2)	0.049 (2)	0.0240 (17)	0.0127 (18)	0.0093 (16)	0.0006 (17)
C45	0.040 (2)	0.038 (2)	0.0267 (18)	0.0076 (17)	0.0032 (16)	−0.0042 (15)
C46	0.0341 (19)	0.037 (2)	0.0333 (18)	0.0026 (15)	0.0040 (16)	−0.0058 (16)
N21	0.0250 (14)	0.0294 (15)	0.0278 (14)	0.0000 (12)	0.0054 (12)	−0.0005 (12)
N22	0.0307 (15)	0.0275 (15)	0.0276 (14)	−0.0030 (12)	0.0086 (12)	−0.0003 (12)
N31	0.0272 (14)	0.0322 (15)	0.0240 (14)	−0.0028 (12)	0.0066 (12)	0.0013 (12)
N32	0.0314 (15)	0.0333 (15)	0.0271 (14)	−0.0042 (13)	0.0103 (12)	0.0004 (12)
N41	0.0305 (14)	0.0282 (15)	0.0273 (14)	0.0015 (12)	0.0052 (12)	−0.0014 (12)
N42	0.0325 (15)	0.0353 (16)	0.0260 (13)	0.0013 (12)	0.0097 (12)	0.0036 (13)
Cl1	0.0527 (6)	0.0692 (7)	0.0497 (5)	0.0080 (5)	0.0197 (5)	0.0077 (5)
Cl2	0.0631 (6)	0.0707 (7)	0.0418 (5)	0.0130 (5)	0.0166 (5)	−0.0041 (5)
Cl3	0.0726 (7)	0.0364 (6)	0.1281 (10)	0.0117 (5)	0.0068 (7)	0.0068 (6)

Geometric parameters (Å, º)

C11—N21	1.325 (3)	N31—C31	1.358 (3)
C11—C12	1.427 (3)	N32—C32	1.363 (3)
C11—C16	1.473 (3)	C31—C36	1.412 (4)
C12—N22	1.323 (3)	C31—C32	1.411 (4)
C12—C13	1.474 (3)	C32—C33	1.416 (4)
C13—C14	1.429 (3)	C33—C34	1.351 (4)
C13—N32	1.328 (3)	C34—C35	1.409 (4)
C14—N31	1.328 (3)	C35—C36	1.366 (4)
C14—C15	1.483 (3)	N41—C41	1.361 (3)
C15—N41	1.333 (3)	N42—C42	1.358 (3)
C15—C16	1.417 (3)	C41—C46	1.418 (4)
C16—N42	1.329 (3)	C41—C42	1.424 (4)
N21—C21	1.359 (3)	C42—C43	1.411 (3)
N22—C22	1.362 (3)	C43—C44	1.358 (4)
C21—C26	1.413 (3)	C44—C45	1.400 (4)
C21—C22	1.422 (3)	C45—C46	1.372 (4)
C22—C23	1.413 (3)	C1—Cl1	1.749 (3)
C23—C24	1.357 (4)	C1—Cl3	1.746 (3)
C24—C25	1.407 (4)	C1—Cl2	1.760 (3)
C25—C26	1.352 (4)
N21—C11—C12	122.2 (3)	C25—C26—C21	119.9 (3)
N21—C11—C16	117.5 (2)	C14—N31—C31	116.8 (2)
C12—C11—C16	120.3 (2)	C13—N32—C32	116.5 (2)
N22—C12—C11	122.0 (2)	N31—C31—C36	119.5 (3)
N22—C12—C13	118.6 (2)	N31—C31—C32	121.4 (3)
C11—C12—C13	119.3 (3)	C36—C31—C32	119.1 (3)
N32—C13—C14	121.9 (2)	N32—C32—C31	121.6 (2)
N32—C13—C12	117.5 (2)	N32—C32—C33	118.8 (3)
C14—C13—C12	120.6 (2)	C31—C32—C33	119.6 (3)
N31—C14—C13	121.9 (2)	C34—C33—C32	119.8 (3)
N31—C14—C15	118.5 (3)	C33—C34—C35	120.9 (3)
C13—C14—C15	119.6 (2)	C36—C35—C34	120.6 (3)
N41—C15—C16	122.6 (2)	C35—C36—C31	119.8 (3)
N41—C15—C14	117.8 (2)	C15—N41—C41	116.3 (2)
C16—C15—C14	119.6 (3)	C16—N42—C42	117.1 (2)
N42—C16—C15	121.6 (3)	N41—C41—C46	119.8 (3)
N42—C16—C11	117.8 (2)	N41—C41—C42	121.4 (3)
C15—C16—C11	120.5 (2)	C46—C41—C42	118.9 (3)
C11—N21—C21	116.7 (2)	N42—C42—C43	119.1 (3)
C12—N22—C22	116.5 (2)	N42—C42—C41	121.0 (2)
N21—C21—C26	119.7 (2)	C43—C42—C41	119.9 (3)
N21—C21—C22	121.1 (2)	C44—C43—C42	119.5 (3)
C26—C21—C22	119.2 (3)	C43—C44—C45	121.4 (3)
N22—C22—C23	119.4 (2)	C46—C45—C44	120.8 (3)
N22—C22—C21	121.4 (3)	C45—C46—C41	119.6 (3)
C23—C22—C21	119.2 (3)	Cl1—C1—Cl3	110.92 (16)
C24—C23—C22	119.9 (3)	Cl1—C1—Cl2	110.23 (16)
C23—C24—C25	120.8 (3)	Cl3—C1—Cl2	110.46 (16)
C26—C25—C24	121.1 (3)