6-Methyl-11a,12-di­hydro-6H-quino­[3,2-b][1,4]­benzo­thia­zine: an amidine formed under unusual conditions

The crystal structure determination of the title compound, C₁₆H₁₄N₂S, confirms the amidine nature of this reaction product. In N,N'-di­phenyl­amidines both phenyl groups are nearly orthogonal with the N-C(-C)=N grouping, whereas in this constrained amidine the benzene groups are substantially less twisted [C-C-N-C torsion angles = -17.2 (7) and 38.1 (6)°]. The result is a slightly cupped mol­ecule with the ring-fused benzene rings appearing like the extended wings of a butterfly. The S-C distances of 1.807 (4) and 1.760 (5) Å are significantly different, with the shorter distance representing the S-C bond to a benzene ring.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.007 Å
• R factor = 0.041
• wR factor = 0.099
• Data-to-parameter ratio = 7.1

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           24.98
         From the CIF: _reflns_number_total               1214
         Count of symmetry unique reflns         1213
         Completeness (_total/calc)            100.08%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured         1
         Fraction of Friedel pairs measured     0.001
         Are heavy atom types Z>Si present          yes
          WARNING: Large fraction of Friedel related reflns may
                   be needed to determine absolute structure

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Computing details

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

(4)

Crystal data

C16H14N2S	F(000) = 560
Mr = 266.35	Dx = 1.364 Mg m^−3
Orthorhombic, Pca21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2ac	Cell parameters from 25 reflections
a = 22.775 (4) Å	θ = 10–25°
b = 5.381 (1) Å	µ = 0.24 mm^−1
c = 10.587 (2) Å	T = 293 K
V = 1297.5 (4) Å^3	Irregular, white
Z = 4	0.40 × 0.30 × 0.08 mm

Data collection

Enraf–Nonius TurboCAD-4 diffractometer	Rint = 0.019
non–profiled ω scans	θmax = 25.0°, θmin = 1.8°
Absorption correction: ψ scan (North, Phillips & Mathews, 1968)	h = −1→27
Tmin = 0.954, Tmax = 0.977	k = 0→6
1274 measured reflections	l = 0→12
1214 independent reflections	3 standard reflections every 120 min
844 reflections with I > 2σ(I)	intensity decay: 1%

Refinement

Refinement on F^2	1 restraint
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.041	w = 1/[σ^2(Fo^2) + (0.0457P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.099	(Δ/σ)max < 0.001
S = 1.07	Δρmax = 0.16 e Å^−3
1214 reflections	Δρmin = −0.20 e Å^−3
172 parameters

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.

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

	x	y	z	Uiso*/Ueq
C1	0.44282 (18)	0.5428 (9)	0.4459 (5)	0.0481 (12)
C2	0.4880 (2)	0.5195 (11)	0.3583 (6)	0.0621 (14)
H2	0.4872	0.3901	0.3001	0.075*
C3	0.5338 (2)	0.6865 (11)	0.3570 (5)	0.0651 (15)
H3	0.5632	0.6733	0.2964	0.078*
C4	0.5358 (2)	0.8722 (10)	0.4454 (6)	0.0663 (15)
H4	0.5668	0.9848	0.4446	0.08*
C5	0.49222 (17)	0.8941 (8)	0.5358 (6)	0.0561 (13)
H5	0.4945	1.0178	0.597	0.067*
C6	0.44493 (16)	0.7300 (8)	0.5349 (5)	0.0464 (11)
C7	0.35008 (18)	0.6674 (8)	0.6054 (5)	0.0424 (11)
C8	0.33665 (18)	0.5082 (9)	0.4924 (4)	0.0466 (12)
H8	0.3233	0.6156	0.4234	0.056*
C9	0.39129 (18)	0.3705 (10)	0.4496 (6)	0.0620 (14)
H9A	0.3993	0.2346	0.5073	0.074*
H9B	0.3848	0.3009	0.3662	0.074*
C10	0.3196 (2)	0.8677 (12)	0.7997 (5)	0.0667 (16)
H10A	0.2856	0.8877	0.8521	0.1*
H10B	0.333	1.0277	0.7716	0.1*
H10C	0.3502	0.7881	0.8473	0.1*
C11	0.2448 (2)	0.6820 (8)	0.6598 (4)	0.0447 (11)
C12	0.20197 (19)	0.8427 (10)	0.7052 (5)	0.0514 (12)
H12	0.213	0.9802	0.7528	0.062*
C13	0.1426 (2)	0.8009 (10)	0.6803 (5)	0.0601 (14)
H13	0.1145	0.9095	0.7118	0.072*
C14	0.1258 (2)	0.5990 (10)	0.6092 (6)	0.0608 (15)
H14	0.0862	0.5683	0.5939	0.073*
C15	0.16821 (19)	0.4428 (10)	0.5609 (5)	0.0589 (15)
H15	0.1571	0.3084	0.5111	0.071*
C16	0.22696 (17)	0.4831 (8)	0.5854 (5)	0.0483 (12)
N1	0.40020 (14)	0.7687 (7)	0.6254 (4)	0.0468 (10)
N2	0.30480 (15)	0.7159 (7)	0.6911 (4)	0.0459 (10)
S1	0.28038 (5)	0.2798 (2)	0.52419 (16)	0.0649 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.042 (2)	0.050 (3)	0.052 (3)	0.004 (2)	−0.007 (3)	0.002 (3)
C2	0.047 (3)	0.074 (3)	0.066 (3)	0.007 (3)	0.002 (3)	−0.005 (4)
C3	0.045 (3)	0.086 (4)	0.064 (4)	0.010 (3)	0.010 (3)	0.012 (4)
C4	0.040 (3)	0.062 (3)	0.097 (4)	−0.002 (2)	0.010 (4)	0.009 (4)
C5	0.038 (2)	0.056 (3)	0.075 (3)	−0.004 (2)	−0.001 (3)	−0.006 (3)
C6	0.037 (2)	0.048 (3)	0.055 (3)	0.006 (2)	−0.006 (3)	0.005 (3)
C7	0.043 (2)	0.038 (3)	0.046 (3)	0.003 (2)	−0.007 (2)	0.010 (3)
C8	0.046 (2)	0.044 (3)	0.050 (3)	−0.007 (2)	−0.006 (2)	0.005 (2)
C9	0.052 (3)	0.059 (3)	0.075 (4)	0.004 (3)	−0.001 (3)	−0.012 (3)
C10	0.055 (3)	0.101 (4)	0.044 (3)	−0.016 (3)	0.002 (3)	−0.017 (3)
C11	0.041 (2)	0.049 (3)	0.044 (3)	−0.012 (2)	−0.002 (2)	0.016 (2)
C12	0.046 (3)	0.056 (3)	0.052 (3)	−0.009 (2)	0.007 (3)	0.001 (3)
C13	0.046 (3)	0.068 (4)	0.066 (4)	0.002 (3)	0.011 (3)	0.012 (3)
C14	0.041 (3)	0.063 (3)	0.078 (4)	−0.010 (3)	−0.004 (3)	0.009 (4)
C15	0.048 (3)	0.057 (3)	0.071 (4)	−0.011 (2)	−0.004 (3)	0.001 (3)
C16	0.043 (3)	0.044 (3)	0.058 (3)	−0.008 (2)	0.000 (2)	0.008 (3)
N1	0.0348 (18)	0.053 (2)	0.052 (2)	−0.0056 (18)	−0.0017 (19)	0.000 (2)
N2	0.0397 (19)	0.059 (3)	0.039 (2)	−0.0085 (19)	−0.0001 (19)	0.005 (2)
S1	0.0509 (6)	0.0467 (7)	0.0972 (11)	−0.0108 (6)	0.0043 (9)	−0.0094 (10)

Geometric parameters (Å, º)

C1—C6	1.381 (6)	C9—H9A	0.97
C1—C2	1.391 (7)	C9—H9B	0.97
C1—C9	1.496 (6)	C10—N2	1.450 (6)
C2—C3	1.377 (7)	C10—H10A	0.96
C2—H2	0.93	C10—H10B	0.96
C3—C4	1.370 (8)	C10—H10C	0.96
C3—H3	0.93	C11—C16	1.390 (6)
C4—C5	1.384 (7)	C11—C12	1.390 (7)
C4—H4	0.93	C11—N2	1.417 (6)
C5—C6	1.393 (5)	C12—C13	1.395 (6)
C5—H5	0.93	C12—H12	0.93
C6—N1	1.414 (5)	C13—C14	1.376 (7)
C7—N1	1.283 (5)	C13—H13	0.93
C7—N2	1.399 (6)	C14—C15	1.379 (7)
C7—C8	1.503 (6)	C14—H14	0.93
C8—C9	1.517 (6)	C15—C16	1.380 (5)
C8—S1	1.807 (4)	C15—H15	0.93
C8—H8	0.98	C16—S1	1.760 (5)
C6—C1—C2	119.7 (4)	C8—C9—H9B	109.6
C6—C1—C9	117.5 (4)	H9A—C9—H9B	108.1
C2—C1—C9	122.8 (5)	N2—C10—H10A	109.5
C3—C2—C1	120.6 (5)	N2—C10—H10B	109.5
C3—C2—H2	119.7	H10A—C10—H10B	109.5
C1—C2—H2	119.7	N2—C10—H10C	109.5
C4—C3—C2	119.6 (5)	H10A—C10—H10C	109.5
C4—C3—H3	120.2	H10B—C10—H10C	109.5
C2—C3—H3	120.2	C16—C11—C12	118.0 (4)
C3—C4—C5	120.7 (5)	C16—C11—N2	120.9 (4)
C3—C4—H4	119.6	C12—C11—N2	121.1 (4)
C5—C4—H4	119.6	C11—C12—C13	121.0 (5)
C4—C5—C6	119.7 (5)	C11—C12—H12	119.5
C4—C5—H5	120.1	C13—C12—H12	119.5
C6—C5—H5	120.1	C14—C13—C12	120.0 (5)
C1—C6—C5	119.6 (5)	C14—C13—H13	120
C1—C6—N1	123.0 (4)	C12—C13—H13	120
C5—C6—N1	117.3 (5)	C13—C14—C15	119.3 (5)
N1—C7—N2	118.0 (4)	C13—C14—H14	120.4
N1—C7—C8	123.7 (4)	C15—C14—H14	120.4
N2—C7—C8	118.2 (4)	C14—C15—C16	120.9 (5)
C7—C8—C9	110.4 (4)	C14—C15—H15	119.6
C7—C8—S1	112.6 (3)	C16—C15—H15	119.6
C9—C8—S1	107.8 (3)	C15—C16—C11	120.8 (4)
C7—C8—H8	108.7	C15—C16—S1	120.2 (4)
C9—C8—H8	108.7	C11—C16—S1	119.0 (3)
S1—C8—H8	108.7	C7—N1—C6	117.8 (4)
C1—C9—C8	110.4 (4)	C7—N2—C11	122.3 (4)
C1—C9—H9A	109.6	C7—N2—C10	116.6 (3)
C8—C9—H9A	109.6	C11—N2—C10	118.8 (4)
C1—C9—H9B	109.6	C16—S1—C8	97.8 (2)