6-[(R)-(2-Hy­droxy-1-phenyl­eth­yl)amino­methyl­idene]-4-(2-phenyl­diazen-1-yl)cyclohexa-2,4-dien-1-one

The title chiral photochromic Schiff base compound, C₂₁H₁₉N₃O₂, was synthesized from (R)-(−)-2-phenyl­glycinol and salicyl­aldehyde of azo­benzene derivative. The mol­ecule exhibits the keto–amine tautomeric form and displays characteristic features of azo­benzene derivatives. The diazenyl group adopts a trans (E) conformation, with N=N bond length of 1.260 (2) Å. The hy­droxy group is involved in an inter­molecular O—H...O hydrogen bond.

Key indicators

• Single-crystal X-ray study
• T = 103 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.031
• wR factor = 0.074
• Data-to-parameter ratio = 14.9

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT029_ALERT_3_B _diffrn_measured_fraction_theta_full value Low .      0.959 Note

Alert level C
PLAT480_ALERT_4_C Long H...A H-Bond Reported H11    ..  O2      ..       2.62 Ang.
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         10 Report
PLAT915_ALERT_3_C No Flack x Check Done: Low Friedel Pair Coverage         78 %
PLAT934_ALERT_3_C Number of (Iobs-Icalc)/SigmaW > 10 Outliers ....          1 Check

Alert level G
PLAT007_ALERT_5_G Number of Unrefined Donor-H Atoms ..............          1 Report
PLAT066_ALERT_1_G Predicted and Reported Tmin&Tmax Range Identical          ? Check
PLAT791_ALERT_4_G The Model has Chirality at C9      (Chiral SPGR)          R Verify
PLAT910_ALERT_3_G Missing # of FCF Reflection(s) Below Theta(Min)           1 Note
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600         73 Note
PLAT978_ALERT_2_G Number C-C Bonds with Positive Residual Density.          4 Note

   0 ALERT level A = Most likely a serious problem - resolve or explain
   1 ALERT level B = A potentially serious problem, consider carefully
   4 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   6 ALERT level G = General information/check it is not something unexpected

   1 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
   5 ALERT type 3 Indicator that the structure quality may be low
   3 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

---

Computing details

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2014); data reduction: SAINT (Bruker, 2014); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

6-[(R)-(2-Hydroxy-1-phenylethyl)aminomethylidene]-4-(2-phenyldiazen-1-yl)cyclohexa-2,4-dien-1-one

Crystal data

C21H19N3O2	F(000) = 364
Mr = 345.39	Dx = 1.330 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
a = 9.0503 (7) Å	Cell parameters from 3069 reflections
b = 5.9762 (5) Å	θ = 2.3–27.7°
c = 16.3508 (12) Å	µ = 0.09 mm^−1
β = 102.732 (1)°	T = 103 K
V = 862.61 (12) Å^3	Prism, orange
Z = 2	0.15 × 0.09 × 0.08 mm

Data collection

Bruker APEXII diffractometer	3542 independent reflections
Radiation source: fine-focus sealed tube	3408 reflections with I > 2σ(I)
Detector resolution: 8.3333 pixels mm^-1	Rint = 0.014
φ and ω scans	θmax = 27.7°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Bruker, 2014)	h = −6→11
Tmin = 0.987, Tmax = 0.993	k = −7→7
4779 measured reflections	l = −20→13

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.031	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.074	w = 1/[σ^2(Fo^2) + (0.0306P)^2 + 0.2577P] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max < 0.001
3542 reflections	Δρmax = 0.24 e Å^−3
238 parameters	Δρmin = −0.20 e Å^−3
1 restraint	Absolute structure: Flack parameter not reliable here
Primary atom site location: structure-invariant direct methods

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. All H atoms were located on difference Fourier maps but C-bound and N-bound H atoms were con­strained using a riding model [C—H = 0.93 Å andU_iso(H) = 1.2U_eq(C) for aromatic H atoms, C—H = 0.98 Å andU_iso(H) = 1.2U_eq(C) for the methine H atom, and N—H = 0.86 Å andU_iso(H) = 1.2U_eq(N)]. The coordinates of the hydroxy H atom were freely refined but its isotropic displacement parameter was considered as 1.5U_eq(O).

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

	x	y	z	Uiso*/Ueq
O1	0.52800 (14)	−0.2877 (3)	0.43795 (9)	0.0208 (3)
H8	0.522 (3)	−0.406 (5)	0.4000 (16)	0.031*
O2	0.47218 (16)	0.3639 (2)	0.32957 (8)	0.0208 (3)
N1	0.74880 (17)	0.2803 (3)	0.01627 (9)	0.0173 (3)
N2	0.66505 (18)	0.1391 (3)	0.04115 (9)	0.0184 (3)
N3	0.34194 (17)	−0.0234 (3)	0.32052 (9)	0.0158 (3)
H3	0.3524	0.1072	0.3431	0.019*
C1	0.9597 (2)	0.0884 (4)	−0.17739 (12)	0.0210 (4)
H1	1.01	0.048	−0.219	0.025*
C2	0.9847 (2)	0.2973 (4)	−0.13999 (12)	0.0218 (4)
H19	1.0508	0.3976	−0.1568	0.026*
C3	0.9102 (2)	0.3558 (3)	−0.07716 (11)	0.0183 (4)
H18	0.9263	0.4958	−0.0519	0.022*
C4	0.81138 (19)	0.2051 (3)	−0.05196 (11)	0.0163 (4)
C5	0.6113 (2)	0.2097 (3)	0.11202 (11)	0.0170 (4)
C6	0.5257 (2)	0.0588 (3)	0.14488 (11)	0.0166 (4)
H15	0.5008	−0.0779	0.1182	0.02*
C7	0.4750 (2)	0.1084 (3)	0.21870 (11)	0.0158 (4)
C8	0.3900 (2)	−0.0539 (3)	0.25210 (11)	0.0161 (4)
H12	0.3677	−0.1886	0.2236	0.019*
C9	0.27104 (19)	−0.1981 (3)	0.36140 (11)	0.0150 (4)
H11	0.2624	−0.3331	0.3266	0.018*
C10	0.1132 (2)	−0.1343 (3)	0.37080 (11)	0.0166 (4)
C11	0.0294 (2)	−0.2918 (4)	0.40452 (12)	0.0210 (4)
H7	0.0719	−0.4302	0.422	0.025*
C12	−0.1174 (2)	−0.2432 (4)	0.41213 (12)	0.0235 (4)
H6	−0.1721	−0.3486	0.4351	0.028*
C13	−0.1823 (2)	−0.0378 (4)	0.38554 (12)	0.0238 (4)
H2	−0.281	−0.0063	0.3897	0.029*
C14	−0.0994 (2)	0.1195 (4)	0.35286 (13)	0.0245 (4)
H5	−0.1423	0.2578	0.3355	0.029*
C15	0.0482 (2)	0.0720 (4)	0.34567 (12)	0.0210 (4)
H4	0.1034	0.1792	0.3239	0.025*
C16	0.3771 (2)	−0.2510 (3)	0.44649 (11)	0.0187 (4)
H9	0.3756	−0.1272	0.4847	0.022*
H10	0.3409	−0.3832	0.4703	0.022*
C17	0.5143 (2)	0.3177 (3)	0.26138 (11)	0.0164 (4)
C18	0.6022 (2)	0.4711 (3)	0.22420 (11)	0.0182 (4)
H14	0.6292	0.6084	0.2499	0.022*
C19	0.6472 (2)	0.4208 (3)	0.15215 (11)	0.0174 (4)
H13	0.702	0.5254	0.1289	0.021*
C20	0.7848 (2)	−0.0038 (3)	−0.09025 (11)	0.0180 (4)
H16	0.7177	−0.1037	−0.0741	0.022*
C21	0.8596 (2)	−0.0612 (3)	−0.15289 (11)	0.0203 (4)
H17	0.8428	−0.2005	−0.1786	0.024*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0164 (6)	0.0203 (7)	0.0247 (7)	0.0002 (6)	0.0027 (5)	−0.0014 (6)
O2	0.0251 (7)	0.0181 (7)	0.0216 (7)	−0.0001 (6)	0.0100 (6)	−0.0037 (5)
N1	0.0174 (7)	0.0173 (8)	0.0167 (7)	0.0003 (7)	0.0028 (6)	0.0009 (6)
N2	0.0185 (7)	0.0203 (9)	0.0166 (7)	0.0007 (7)	0.0041 (6)	0.0013 (6)
N3	0.0159 (7)	0.0126 (8)	0.0198 (7)	−0.0002 (6)	0.0056 (6)	−0.0016 (6)
C1	0.0166 (9)	0.0301 (11)	0.0164 (8)	0.0030 (8)	0.0040 (7)	0.0016 (8)
C2	0.0176 (9)	0.0277 (11)	0.0201 (9)	−0.0037 (8)	0.0040 (7)	0.0038 (8)
C3	0.0173 (9)	0.0175 (10)	0.0186 (9)	−0.0024 (8)	0.0004 (7)	0.0011 (7)
C4	0.0136 (8)	0.0190 (9)	0.0152 (8)	0.0015 (7)	0.0008 (7)	0.0023 (7)
C5	0.0154 (8)	0.0179 (9)	0.0171 (8)	0.0020 (8)	0.0022 (7)	0.0001 (7)
C6	0.0162 (8)	0.0160 (9)	0.0171 (8)	0.0002 (7)	0.0022 (7)	−0.0010 (7)
C7	0.0140 (8)	0.0157 (9)	0.0169 (8)	0.0019 (7)	0.0020 (7)	0.0015 (7)
C8	0.0136 (8)	0.0173 (9)	0.0164 (8)	0.0024 (7)	0.0012 (6)	−0.0007 (7)
C9	0.0158 (8)	0.0133 (9)	0.0170 (8)	−0.0002 (7)	0.0060 (7)	−0.0003 (7)
C10	0.0159 (8)	0.0205 (9)	0.0138 (8)	−0.0008 (7)	0.0041 (7)	−0.0029 (7)
C11	0.0219 (9)	0.0193 (9)	0.0221 (9)	−0.0006 (8)	0.0055 (7)	0.0009 (8)
C12	0.0220 (9)	0.0276 (12)	0.0229 (10)	−0.0067 (9)	0.0090 (8)	0.0000 (8)
C13	0.0155 (9)	0.0345 (12)	0.0216 (9)	0.0011 (9)	0.0050 (7)	−0.0042 (9)
C14	0.0208 (9)	0.0248 (11)	0.0278 (10)	0.0053 (9)	0.0055 (8)	0.0006 (9)
C15	0.0204 (9)	0.0211 (10)	0.0222 (9)	0.0007 (8)	0.0064 (7)	0.0020 (8)
C16	0.0175 (8)	0.0205 (10)	0.0179 (9)	0.0005 (8)	0.0038 (7)	−0.0013 (7)
C17	0.0133 (8)	0.0170 (10)	0.0184 (8)	0.0039 (7)	0.0026 (7)	0.0012 (7)
C18	0.0173 (9)	0.0135 (9)	0.0228 (9)	0.0005 (8)	0.0025 (7)	−0.0015 (8)
C19	0.0155 (8)	0.0157 (9)	0.0208 (9)	−0.0004 (7)	0.0037 (7)	0.0029 (7)
C20	0.0165 (9)	0.0195 (10)	0.0176 (8)	−0.0008 (8)	0.0029 (7)	0.0028 (7)
C21	0.0212 (9)	0.0201 (10)	0.0184 (9)	0.0020 (8)	0.0016 (7)	−0.0001 (8)

Geometric parameters (Å, º)

O1—C16	1.420 (2)	C9—C10	1.519 (2)
O1—H8	0.93 (3)	C9—C16	1.539 (2)
O2—C17	1.285 (2)	C9—H11	0.98
N1—N2	1.260 (2)	C10—C15	1.388 (3)
N1—C4	1.430 (2)	C10—C11	1.397 (3)
N2—C5	1.416 (2)	C11—C12	1.392 (3)
N3—C8	1.299 (2)	C11—H7	0.93
N3—C9	1.462 (2)	C12—C13	1.389 (3)
N3—H3	0.86	C12—H6	0.93
C1—C2	1.387 (3)	C13—C14	1.381 (3)
C1—C21	1.393 (3)	C13—H2	0.93
C1—H1	0.93	C14—C15	1.396 (3)
C2—C3	1.392 (3)	C14—H5	0.93
C2—H19	0.93	C15—H4	0.93
C3—C4	1.394 (3)	C16—H9	0.97
C3—H18	0.93	C16—H10	0.97
C4—C20	1.394 (3)	C17—C18	1.434 (3)
C5—C6	1.373 (3)	C18—C19	1.362 (3)
C5—C19	1.426 (3)	C18—H14	0.93
C6—C7	1.414 (2)	C19—H13	0.93
C6—H15	0.93	C20—C21	1.390 (3)
C7—C8	1.420 (3)	C20—H16	0.93
C7—C17	1.438 (3)	C21—H17	0.93
C8—H12	0.93
C16—O1—H8	105.7 (16)	C11—C10—C9	118.38 (17)
N2—N1—C4	114.28 (15)	C12—C11—C10	120.44 (19)
N1—N2—C5	113.82 (15)	C12—C11—H7	119.8
C8—N3—C9	123.89 (16)	C10—C11—H7	119.8
C8—N3—H3	118.1	C13—C12—C11	120.19 (19)
C9—N3—H3	118.1	C13—C12—H6	119.9
C2—C1—C21	120.29 (18)	C11—C12—H6	119.9
C2—C1—H1	119.9	C14—C13—C12	119.62 (18)
C21—C1—H1	119.9	C14—C13—H2	120.2
C1—C2—C3	119.54 (19)	C12—C13—H2	120.2
C1—C2—H19	120.2	C13—C14—C15	120.4 (2)
C3—C2—H19	120.2	C13—C14—H5	119.8
C2—C3—C4	120.17 (19)	C15—C14—H5	119.8
C2—C3—H18	119.9	C10—C15—C14	120.42 (19)
C4—C3—H18	119.9	C10—C15—H4	119.8
C3—C4—C20	120.31 (17)	C14—C15—H4	119.8
C3—C4—N1	114.70 (17)	O1—C16—C9	111.39 (14)
C20—C4—N1	124.95 (16)	O1—C16—H9	109.4
C6—C5—N2	116.70 (17)	C9—C16—H9	109.4
C6—C5—C19	119.47 (17)	O1—C16—H10	109.4
N2—C5—C19	123.76 (17)	C9—C16—H10	109.4
C5—C6—C7	120.89 (18)	H9—C16—H10	108.0
C5—C6—H15	119.6	O2—C17—C18	121.93 (17)
C7—C6—H15	119.6	O2—C17—C7	121.24 (17)
C6—C7—C8	119.36 (17)	C18—C17—C7	116.84 (16)
C6—C7—C17	120.28 (17)	C19—C18—C17	121.69 (18)
C8—C7—C17	120.31 (16)	C19—C18—H14	119.2
N3—C8—C7	123.23 (18)	C17—C18—H14	119.2
N3—C8—H12	118.4	C18—C19—C5	120.78 (17)
C7—C8—H12	118.4	C18—C19—H13	119.6
N3—C9—C10	112.59 (15)	C5—C19—H13	119.6
N3—C9—C16	108.09 (14)	C21—C20—C4	119.22 (18)
C10—C9—C16	111.93 (14)	C21—C20—H16	120.4
N3—C9—H11	108.0	C4—C20—H16	120.4
C10—C9—H11	108.0	C20—C21—C1	120.47 (19)
C16—C9—H11	108.0	C20—C21—H17	119.8
C15—C10—C11	118.95 (17)	C1—C21—H17	119.8
C15—C10—C9	122.66 (17)
C4—N1—N2—C5	176.27 (14)	C9—C10—C11—C12	−178.17 (17)
C21—C1—C2—C3	0.6 (3)	C10—C11—C12—C13	0.5 (3)
C1—C2—C3—C4	0.1 (3)	C11—C12—C13—C14	−1.1 (3)
C2—C3—C4—C20	−0.9 (3)	C12—C13—C14—C15	0.7 (3)
C2—C3—C4—N1	176.58 (16)	C11—C10—C15—C14	−1.0 (3)
N2—N1—C4—C3	−176.93 (16)	C9—C10—C15—C14	177.65 (18)
N2—N1—C4—C20	0.5 (2)	C13—C14—C15—C10	0.4 (3)
N1—N2—C5—C6	−176.78 (16)	N3—C9—C16—O1	−49.4 (2)
N1—N2—C5—C19	0.2 (2)	C10—C9—C16—O1	−173.93 (16)
N2—C5—C6—C7	175.99 (16)	C6—C7—C17—O2	−178.44 (17)
C19—C5—C6—C7	−1.1 (3)	C8—C7—C17—O2	−1.0 (3)
C5—C6—C7—C8	−178.38 (17)	C6—C7—C17—C18	1.6 (2)
C5—C6—C7—C17	−0.9 (3)	C8—C7—C17—C18	179.09 (17)
C9—N3—C8—C7	−172.05 (16)	O2—C17—C18—C19	179.68 (17)
C6—C7—C8—N3	178.53 (17)	C7—C17—C18—C19	−0.4 (3)
C17—C7—C8—N3	1.0 (3)	C17—C18—C19—C5	−1.6 (3)
C8—N3—C9—C10	−122.26 (18)	C6—C5—C19—C18	2.4 (3)
C8—N3—C9—C16	113.59 (19)	N2—C5—C19—C18	−174.51 (17)
N3—C9—C10—C15	−2.3 (2)	C3—C4—C20—C21	1.0 (3)
C16—C9—C10—C15	119.73 (19)	N1—C4—C20—C21	−176.29 (17)
N3—C9—C10—C11	176.36 (16)	C4—C20—C21—C1	−0.2 (3)
C16—C9—C10—C11	−61.6 (2)	C2—C1—C21—C20	−0.6 (3)
C15—C10—C11—C12	0.5 (3)

Hydrogen-bond geometry (Å, º)

Cg1 and Cg2 are the centroids of the C1–C4/C20/C21 and C5–C7/C17–C19 rings, respectively.

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3···O2	0.86	1.92	2.587 (2)	134
O1—H8···O2^i	0.93 (3)	1.79 (3)	2.708 (2)	168 (2)
C16—H9···O1^ii	0.97	2.45	3.355 (2)	156
C9—H11···O2^i	0.98	2.62	3.294 (2)	127
C14—H5···Cg2^iii	0.93	3.20	3.722 (2)	118
C8—H12···Cg1^iv	0.93	2.75	3.458 (2)	134
C20—H16···Cg2^iv	0.93	2.89	3.480 (2)	122
C3—H18···Cg1^v	0.93	3.02	3.711 (2)	132

Symmetry codes: (i) x, y−1, z; (ii) −x+1, y+1/2, −z+1; (iii) x−1, y, z; (iv) −x+1, y−1/2, −z; (v) −x+1, y+1/2, −z.