Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536805027613/hg6233sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536805027613/hg6233Isup2.hkl |
CCDC reference: 287591
Key indicators
- Single-crystal X-ray study
- T = 90 K
- Mean (C-C) = 0.004 Å
- R factor = 0.049
- wR factor = 0.109
- Data-to-parameter ratio = 15.8
checkCIF/PLATON results
No syntax errors found
Alert level C PLAT410_ALERT_2_C Short Intra H...H Contact H10 .. H19 .. 1.98 Ang.
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 1 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 0 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion
A mixture of benzo[4,5]imidazo[2,1-b]thiazol-3-one (0.02 mol) and naphthaldehyde (0.02 mol) was stirred under reflux in CH3COONa/CH3COOH solution (40 ml) for 90 min. After cooling and filtration, the title compound was recrystallized from acetic acid. A quantity of (I) (15 mg) was dissolved in trichloromethane (20 ml) and the solution kept at room temperature for 7 d. Slow solvent evaporation gave yellow single crystals of (I) suitable for X-ray analysis (m.p. 486–488 K). Spectroscopic analysis: 1H NMR (Frequency?, Medium?, δ, p.p.m.): 7.27–7.71 (m, 11H, ArH), 7.42 (s, 1H, –CH).
H atoms were positioned geometrically, with C—H = 0.93–0.98 Å, and refined in a riding model, with Uiso(H) = 1.5Ueq(carrier).
Data collection: SMART (Bruker, 1997); cell refinement: SMART; data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL.
Fig. 1. The molecular structure of (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. | |
Fig. 2. Please provide caption. |
C20H12N2OS | F(000) = 680 |
Mr = 328.38 | Dx = 1.496 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 894 reflections |
a = 6.8627 (16) Å | θ = 3.0–25.4° |
b = 7.9031 (19) Å | µ = 0.23 mm−1 |
c = 27.010 (6) Å | T = 90 K |
β = 95.406 (4)° | Plate, yellow |
V = 1458.4 (6) Å3 | 0.04 × 0.04 × 0.01 mm |
Z = 4 |
Bruker SMART CCD area-detector diffractometer | 3432 independent reflections |
Radiation source: fine-focus sealed tube | 1989 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.071 |
ϕ and ω scans | θmax = 27.9°, θmin = 2.7° |
Absorption correction: multi-scan (SADABS; Bruker, 1997) | h = −8→8 |
Tmin = 0.980, Tmax = 0.998 | k = −10→8 |
8139 measured reflections | l = −28→35 |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.049 | w = 1/[σ2(Fo2) + (0.0394P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.109 | (Δ/σ)max < 0.001 |
S = 0.95 | Δρmax = 0.34 e Å−3 |
3432 reflections | Δρmin = −0.35 e Å−3 |
217 parameters |
C20H12N2OS | V = 1458.4 (6) Å3 |
Mr = 328.38 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 6.8627 (16) Å | µ = 0.23 mm−1 |
b = 7.9031 (19) Å | T = 90 K |
c = 27.010 (6) Å | 0.04 × 0.04 × 0.01 mm |
β = 95.406 (4)° |
Bruker SMART CCD area-detector diffractometer | 3432 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 1997) | 1989 reflections with I > 2σ(I) |
Tmin = 0.980, Tmax = 0.998 | Rint = 0.071 |
8139 measured reflections |
R[F2 > 2σ(F2)] = 0.049 | 0 restraints |
wR(F2) = 0.109 | H-atom parameters constrained |
S = 0.95 | Δρmax = 0.34 e Å−3 |
3432 reflections | Δρmin = −0.35 e Å−3 |
217 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | −0.1244 (4) | 0.3340 (3) | −0.02914 (9) | 0.0133 (6) | |
C2 | −0.3138 (4) | 0.3939 (3) | −0.03455 (10) | 0.0157 (5) | |
H2 | −0.4016 | 0.3755 | −0.0099 | 0.019* | |
C3 | −0.3695 (4) | 0.4823 (3) | −0.07788 (10) | 0.0176 (6) | |
H3 | −0.4989 | 0.5257 | −0.0833 | 0.021* | |
C4 | −0.2387 (4) | 0.5086 (3) | −0.11379 (10) | 0.0179 (6) | |
H4 | −0.2811 | 0.5710 | −0.1429 | 0.022* | |
C5 | −0.0492 (4) | 0.4466 (3) | −0.10822 (10) | 0.0175 (6) | |
H5 | 0.0378 | 0.4639 | −0.1331 | 0.021* | |
C6 | 0.0087 (4) | 0.3581 (3) | −0.06499 (9) | 0.0136 (6) | |
C7 | 0.1659 (4) | 0.2148 (3) | −0.00776 (9) | 0.0135 (6) | |
C8 | −0.0527 (4) | 0.1745 (3) | 0.05420 (9) | 0.0138 (6) | |
C9 | 0.1285 (3) | 0.0860 (3) | 0.07529 (9) | 0.0122 (5) | |
C10 | 0.1329 (4) | 0.0146 (3) | 0.12013 (9) | 0.0134 (6) | |
H10 | 0.0130 | 0.0217 | 0.1349 | 0.016* | |
C11 | 0.2890 (4) | −0.0722 (3) | 0.15048 (9) | 0.0147 (6) | |
C12 | 0.4650 (3) | −0.1119 (3) | 0.13241 (9) | 0.0156 (6) | |
H12 | 0.4853 | −0.0806 | 0.0993 | 0.019* | |
C13 | 0.6139 (4) | −0.1967 (3) | 0.16119 (10) | 0.0181 (6) | |
H13 | 0.7330 | −0.2221 | 0.1475 | 0.022* | |
C14 | 0.5897 (4) | −0.2433 (3) | 0.20888 (10) | 0.0187 (6) | |
H14 | 0.6913 | −0.3020 | 0.2281 | 0.022* | |
C15 | 0.4137 (4) | −0.2045 (3) | 0.22993 (9) | 0.0160 (6) | |
C16 | 0.3897 (4) | −0.2469 (3) | 0.28003 (10) | 0.0192 (6) | |
H16 | 0.4924 | −0.3041 | 0.2993 | 0.023* | |
C17 | 0.2235 (4) | −0.2077 (3) | 0.30112 (10) | 0.0200 (6) | |
H17 | 0.2111 | −0.2353 | 0.3349 | 0.024* | |
C18 | 0.0699 (4) | −0.1259 (3) | 0.27235 (10) | 0.0181 (6) | |
H18 | −0.0477 | −0.1003 | 0.2867 | 0.022* | |
C19 | 0.0878 (4) | −0.0830 (3) | 0.22412 (9) | 0.0156 (6) | |
H19 | −0.0179 | −0.0272 | 0.2056 | 0.019* | |
C20 | 0.2595 (4) | −0.1192 (3) | 0.20084 (9) | 0.0139 (6) | |
N1 | 0.1914 (3) | 0.2805 (3) | −0.05031 (8) | 0.0158 (5) | |
N2 | −0.0187 (3) | 0.2406 (3) | 0.00826 (7) | 0.0125 (5) | |
O1 | −0.2052 (2) | 0.1884 (2) | 0.07316 (6) | 0.0177 (4) | |
S1 | 0.31774 (9) | 0.09958 (8) | 0.03509 (2) | 0.01514 (17) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0160 (14) | 0.0107 (13) | 0.0126 (13) | −0.0044 (11) | −0.0020 (10) | −0.0005 (11) |
C2 | 0.0148 (13) | 0.0133 (13) | 0.0193 (14) | −0.0026 (12) | 0.0026 (10) | −0.0026 (12) |
C3 | 0.0159 (14) | 0.0143 (14) | 0.0216 (16) | −0.0001 (11) | −0.0033 (12) | −0.0032 (12) |
C4 | 0.0226 (16) | 0.0107 (14) | 0.0194 (15) | −0.0013 (12) | −0.0037 (12) | 0.0043 (11) |
C5 | 0.0208 (15) | 0.0153 (14) | 0.0168 (15) | −0.0027 (12) | 0.0025 (11) | −0.0011 (11) |
C6 | 0.0149 (14) | 0.0112 (13) | 0.0147 (14) | −0.0011 (11) | 0.0015 (11) | 0.0002 (11) |
C7 | 0.0130 (13) | 0.0132 (14) | 0.0141 (14) | −0.0015 (11) | 0.0009 (10) | 0.0009 (11) |
C8 | 0.0155 (14) | 0.0124 (14) | 0.0133 (14) | −0.0044 (11) | 0.0003 (11) | −0.0014 (10) |
C9 | 0.0100 (13) | 0.0146 (14) | 0.0121 (13) | −0.0022 (11) | 0.0017 (10) | 0.0001 (11) |
C10 | 0.0125 (13) | 0.0116 (13) | 0.0164 (14) | −0.0014 (11) | 0.0029 (10) | −0.0045 (11) |
C11 | 0.0170 (14) | 0.0123 (14) | 0.0145 (14) | −0.0016 (11) | −0.0007 (11) | −0.0008 (11) |
C12 | 0.0170 (14) | 0.0142 (14) | 0.0153 (14) | −0.0005 (12) | −0.0003 (11) | −0.0035 (11) |
C13 | 0.0134 (14) | 0.0206 (15) | 0.0204 (15) | 0.0033 (12) | 0.0017 (11) | −0.0013 (12) |
C14 | 0.0126 (14) | 0.0176 (15) | 0.0245 (15) | 0.0027 (11) | −0.0058 (11) | −0.0003 (12) |
C15 | 0.0160 (14) | 0.0145 (14) | 0.0171 (14) | −0.0017 (11) | −0.0008 (11) | −0.0023 (11) |
C16 | 0.0250 (16) | 0.0148 (15) | 0.0167 (15) | 0.0018 (12) | −0.0037 (12) | 0.0016 (11) |
C17 | 0.0276 (16) | 0.0188 (15) | 0.0138 (14) | −0.0064 (13) | 0.0026 (12) | −0.0002 (12) |
C18 | 0.0157 (14) | 0.0206 (16) | 0.0183 (15) | 0.0005 (12) | 0.0029 (11) | −0.0033 (12) |
C19 | 0.0123 (13) | 0.0175 (14) | 0.0162 (14) | −0.0009 (12) | −0.0032 (10) | −0.0009 (12) |
C20 | 0.0175 (14) | 0.0097 (14) | 0.0141 (14) | −0.0012 (11) | −0.0011 (10) | −0.0027 (11) |
N1 | 0.0129 (12) | 0.0168 (12) | 0.0177 (12) | −0.0011 (10) | 0.0013 (9) | −0.0003 (10) |
N2 | 0.0129 (11) | 0.0116 (11) | 0.0130 (12) | −0.0006 (9) | 0.0005 (9) | 0.0007 (9) |
O1 | 0.0142 (10) | 0.0227 (11) | 0.0165 (10) | 0.0008 (8) | 0.0021 (8) | 0.0016 (8) |
S1 | 0.0125 (3) | 0.0175 (4) | 0.0155 (3) | 0.0014 (3) | 0.0015 (2) | 0.0018 (3) |
C1—C2 | 1.379 (3) | C10—C11 | 1.458 (3) |
C1—N2 | 1.397 (3) | C10—H10 | 0.9500 |
C1—C6 | 1.405 (3) | C11—C12 | 1.380 (3) |
C2—C3 | 1.386 (3) | C11—C20 | 1.442 (3) |
C2—H2 | 0.9500 | C12—C13 | 1.396 (3) |
C3—C4 | 1.398 (4) | C12—H12 | 0.9500 |
C3—H3 | 0.9500 | C13—C14 | 1.365 (4) |
C4—C5 | 1.385 (3) | C13—H13 | 0.9500 |
C4—H4 | 0.9500 | C14—C15 | 1.416 (3) |
C5—C6 | 1.387 (3) | C14—H14 | 0.9500 |
C5—H5 | 0.9500 | C15—C16 | 1.419 (4) |
C6—N1 | 1.418 (3) | C15—C20 | 1.426 (3) |
C7—N1 | 1.288 (3) | C16—C17 | 1.358 (4) |
C7—N2 | 1.392 (3) | C16—H16 | 0.9500 |
C7—S1 | 1.740 (3) | C17—C18 | 1.406 (4) |
C8—O1 | 1.212 (3) | C17—H17 | 0.9500 |
C8—N2 | 1.386 (3) | C18—C19 | 1.363 (3) |
C8—C9 | 1.493 (3) | C18—H18 | 0.9500 |
C9—C10 | 1.334 (3) | C19—C20 | 1.416 (3) |
C9—S1 | 1.773 (2) | C19—H19 | 0.9500 |
C2—C1—N2 | 132.7 (2) | C11—C12—C13 | 122.1 (2) |
C2—C1—C6 | 123.2 (2) | C11—C12—H12 | 119.0 |
N2—C1—C6 | 104.1 (2) | C13—C12—H12 | 119.0 |
C1—C2—C3 | 116.4 (2) | C14—C13—C12 | 120.5 (2) |
C1—C2—H2 | 121.8 | C14—C13—H13 | 119.8 |
C3—C2—H2 | 121.8 | C12—C13—H13 | 119.8 |
C2—C3—C4 | 121.2 (2) | C13—C14—C15 | 120.3 (2) |
C2—C3—H3 | 119.4 | C13—C14—H14 | 119.8 |
C4—C3—H3 | 119.4 | C15—C14—H14 | 119.8 |
C5—C4—C3 | 122.0 (2) | C14—C15—C16 | 120.8 (2) |
C5—C4—H4 | 119.0 | C14—C15—C20 | 119.8 (2) |
C3—C4—H4 | 119.0 | C16—C15—C20 | 119.4 (2) |
C4—C5—C6 | 117.5 (2) | C17—C16—C15 | 121.6 (2) |
C4—C5—H5 | 121.2 | C17—C16—H16 | 119.2 |
C6—C5—H5 | 121.2 | C15—C16—H16 | 119.2 |
C5—C6—C1 | 119.7 (2) | C16—C17—C18 | 119.2 (2) |
C5—C6—N1 | 129.0 (2) | C16—C17—H17 | 120.4 |
C1—C6—N1 | 111.3 (2) | C18—C17—H17 | 120.4 |
N1—C7—N2 | 115.0 (2) | C19—C18—C17 | 120.8 (2) |
N1—C7—S1 | 133.0 (2) | C19—C18—H18 | 119.6 |
N2—C7—S1 | 112.05 (17) | C17—C18—H18 | 119.6 |
O1—C8—N2 | 124.7 (2) | C18—C19—C20 | 121.9 (2) |
O1—C8—C9 | 127.0 (2) | C18—C19—H19 | 119.1 |
N2—C8—C9 | 108.3 (2) | C20—C19—H19 | 119.1 |
C10—C9—C8 | 119.4 (2) | C19—C20—C15 | 117.1 (2) |
C10—C9—S1 | 128.8 (2) | C19—C20—C11 | 124.3 (2) |
C8—C9—S1 | 111.72 (17) | C15—C20—C11 | 118.6 (2) |
C9—C10—C11 | 131.5 (2) | C7—N1—C6 | 103.5 (2) |
C9—C10—H10 | 114.3 | C8—N2—C7 | 117.3 (2) |
C11—C10—H10 | 114.3 | C8—N2—C1 | 136.6 (2) |
C12—C11—C20 | 118.7 (2) | C7—N2—C1 | 106.1 (2) |
C12—C11—C10 | 121.9 (2) | C7—S1—C9 | 90.68 (12) |
C20—C11—C10 | 119.4 (2) | ||
N2—C1—C2—C3 | −179.4 (3) | C18—C19—C20—C15 | 0.6 (4) |
C6—C1—C2—C3 | −0.4 (4) | C18—C19—C20—C11 | −178.0 (2) |
C1—C2—C3—C4 | −0.1 (4) | C14—C15—C20—C19 | −179.6 (2) |
C2—C3—C4—C5 | 0.8 (4) | C16—C15—C20—C19 | −0.6 (3) |
C3—C4—C5—C6 | −0.9 (4) | C14—C15—C20—C11 | −0.9 (4) |
C4—C5—C6—C1 | 0.4 (4) | C16—C15—C20—C11 | 178.0 (2) |
C4—C5—C6—N1 | 179.3 (2) | C12—C11—C20—C19 | 178.7 (2) |
C2—C1—C6—C5 | 0.3 (4) | C10—C11—C20—C19 | −1.6 (4) |
N2—C1—C6—C5 | 179.5 (2) | C12—C11—C20—C15 | 0.1 (4) |
C2—C1—C6—N1 | −178.8 (2) | C10—C11—C20—C15 | 179.8 (2) |
N2—C1—C6—N1 | 0.4 (3) | N2—C7—N1—C6 | −0.1 (3) |
O1—C8—C9—C10 | −1.3 (4) | S1—C7—N1—C6 | −179.5 (2) |
N2—C8—C9—C10 | 178.6 (2) | C5—C6—N1—C7 | −179.2 (3) |
O1—C8—C9—S1 | −179.3 (2) | C1—C6—N1—C7 | −0.2 (3) |
N2—C8—C9—S1 | 0.7 (3) | O1—C8—N2—C7 | 179.2 (2) |
C8—C9—C10—C11 | −177.0 (2) | C9—C8—N2—C7 | −0.7 (3) |
S1—C9—C10—C11 | 0.5 (4) | O1—C8—N2—C1 | 0.0 (5) |
C9—C10—C11—C12 | −8.0 (4) | C9—C8—N2—C1 | −179.9 (3) |
C9—C10—C11—C20 | 172.3 (3) | N1—C7—N2—C8 | −179.1 (2) |
C20—C11—C12—C13 | 0.4 (4) | S1—C7—N2—C8 | 0.4 (3) |
C10—C11—C12—C13 | −179.3 (2) | N1—C7—N2—C1 | 0.4 (3) |
C11—C12—C13—C14 | −0.1 (4) | S1—C7—N2—C1 | 179.86 (17) |
C12—C13—C14—C15 | −0.7 (4) | C2—C1—N2—C8 | −2.1 (5) |
C13—C14—C15—C16 | −177.7 (2) | C6—C1—N2—C8 | 178.8 (3) |
C13—C14—C15—C20 | 1.2 (4) | C2—C1—N2—C7 | 178.7 (3) |
C14—C15—C16—C17 | 178.7 (2) | C6—C1—N2—C7 | −0.4 (2) |
C20—C15—C16—C17 | −0.2 (4) | N1—C7—S1—C9 | 179.4 (3) |
C15—C16—C17—C18 | 1.2 (4) | N2—C7—S1—C9 | 0.01 (19) |
C16—C17—C18—C19 | −1.3 (4) | C10—C9—S1—C7 | −178.1 (3) |
C17—C18—C19—C20 | 0.4 (4) | C8—C9—S1—C7 | −0.40 (19) |
Experimental details
Crystal data | |
Chemical formula | C20H12N2OS |
Mr | 328.38 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 90 |
a, b, c (Å) | 6.8627 (16), 7.9031 (19), 27.010 (6) |
β (°) | 95.406 (4) |
V (Å3) | 1458.4 (6) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.23 |
Crystal size (mm) | 0.04 × 0.04 × 0.01 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 1997) |
Tmin, Tmax | 0.980, 0.998 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8139, 3432, 1989 |
Rint | 0.071 |
(sin θ/λ)max (Å−1) | 0.658 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.049, 0.109, 0.95 |
No. of reflections | 3432 |
No. of parameters | 217 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.34, −0.35 |
Computer programs: SMART (Bruker, 1997), SMART, SAINT (Bruker, 1997), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 1997), SHELXTL.
C1—N2 | 1.397 (3) | C8—O1 | 1.212 (3) |
C1—C6 | 1.405 (3) | C8—N2 | 1.386 (3) |
C6—N1 | 1.418 (3) | C8—C9 | 1.493 (3) |
C7—N1 | 1.288 (3) | C9—C10 | 1.334 (3) |
C7—N2 | 1.392 (3) | C9—S1 | 1.773 (2) |
C7—S1 | 1.740 (3) | ||
N2—C1—C6 | 104.1 (2) | N2—C8—C9 | 108.3 (2) |
C1—C6—N1 | 111.3 (2) | C8—C9—S1 | 111.72 (17) |
N1—C7—N2 | 115.0 (2) | C7—N1—C6 | 103.5 (2) |
N1—C7—S1 | 133.0 (2) | C8—N2—C7 | 117.3 (2) |
N2—C7—S1 | 112.05 (17) | C8—N2—C1 | 136.6 (2) |
O1—C8—N2 | 124.7 (2) | C7—N2—C1 | 106.1 (2) |
O1—C8—C9 | 127.0 (2) | C7—S1—C9 | 90.68 (12) |
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Dihydroimidazoles are reported to exhibit diverse biological and pharmacological properties. Examples of these include vasodepressor, sympathomimetic, antihistaminic, histamine-like and cholinomimetic activity (Gilman & Goodman, 2001; Greenhill & Lue, 1993). Dihydroimidazoles, such as midaglizole, deriglidole and efaroxan, have been found to be potent antihyperglycaemic agents (Bihan et al., 1999). Thus, there has been considerable interest in the chemistry of dihydroimidazole and its derivatives in recent years. In this paper, the structure of the title compound, (I), is reported.
The molecular structure of (I) is illustrated in Fig. 1. The heterocyclic ring system is essentially planar, with a mean deviation of 0.0067 (3) Å. Selected bond lengths and angles are listed in Table 1. Taking account of the different substitution patterns, the geometry of the heterocyclic ring system compares favourably with that in the related compounds (2Z)-2-[(anthracen-9-yl)methylene]-5,6-dihydroimidazo[2,1-b]thiazol-3(2H)-one (Liang & Li, 2005) and 6-(4-chlorobenzylidene)-2,3-dihydroimidazo[2,1-b]thiazol-5(6H)-one (Karolak-Wojciechowska & Kiec-Kononowicz, 1991). The naphthalene ring system is planar to within 0.0135 (3) Å. The dihedral angle between the naphthalene plane and the heterocyclic ring system is 9.3 (3)°.