N-[Phen­yl(piperidin-1-yl)meth­yl]-1,3,4-thia­diazol-2-amine

In the crystal structure of the title compound, C₁₄H₁₈N₄S, there is a chiral C atom with a tetra­hedral configuration which connects two N atoms from piperidine and 2-amino-1,3,4-thia­diazole groups, one C atom from the benzene ring, and one H atom. A centrosymmetric dimer is constructed by a pair of chiral mol­ecules of types S and R via inter­molecular N—H...N hydrogen bonds, forming an S²₂(8) ring. In addition, C—H...N weak inter­actions link the dimers into an infinite supramolecular sheet.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.053
• wR factor = 0.123
• Data-to-parameter ratio = 20.3

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT322_ALERT_2_C Check Hybridisation of  S1     in Main Residue .          ?

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K
PLAT793_ALERT_1_G Check the Absolute Configuration of C3     .....          S

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   3 ALERT level G = General alerts; check

   4 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
   0 ALERT type 5 Informative message, check

---

S1. Comment

Aminals, which are usually used as protecting groups for aldehydes (Jurčík & Wilhelm, 2004) in organic syntheses, can be either of open-chain or cyclic form. However, a few crystal structures of the open-chain aminals are reported yet (Wu et al., 1998). In this work, we intended to prepare Schiff ligand using benzaldehyde and primary amine in the presence of piperidine as a catalyst (Dawood et al., 2005; Fleita et al., 2005). But the result product was characterized structurally to be an open-chain aminal N-(phenyl (piperidin-1-yl)methyl)-1,3,4-thiadiazol-2-amine (I) with a chiral carbon as shown in the scheme.

As shown in Fig.1, the title compound I contains a chiral carbon atom C3 showing a tetrahedral configuration that connects the N3 atom from 2-amino-1,3,4-thiadiazole, N4 atom from piperidine, C2 atom from benzene ring and H3A atom. The piperidine ring adopts a normal chair conformation. Atoms C1, C2, N1, N2 and S1 compose the thiadiazole ring which has an excellent coplanarity with tiny deviations (max. 0.0084 (14) to min. 0.0012 (12) Å) from its least-square plane. The dihedral angle between the benzene and thiadiazole planes is 56.23 (6) °. The torsion angles C2—N3—C3—N4 and C2—N3—C3—C4 are 50.70 (23) ° and 177.19 (17) °, respectively.

The bond angles around C3 are 108.45 (15) °, 109.49 (15) °, 115.22 (15) ° for N3—C3—N4, N3—C3—C4, N4—C3—C4, respectively, indicating the sp³ hybridization of C3. The bond lengths of C3—N3 and C3—N4 with 1.459 (3) Å and 1.469 (2) Å fall in the normal range of C—N single bond (1.470 Å) (Allen et al., 1987) and the C3—C4 bond length of 1.516 (3) Å comply exactly with the C—C single bond rule (about 1.51 Å) (Glusker et al., 1995). The C2—N3 (1.354 (2) Å) bond has partial double-bond character, which could be attributed to conjugation of the five-membered thiadiazole ring. Few crystal structures that have similar tetrahedral configuration of the carbon atom were reported (Khrustalev et al., 1998; Wu et al., 1998).

In the crystal structure of I, a pair of molecules with S and R configuration are linked into a dimer via N—H···N intermolecular hydrogen bonds containing a R²₂(8) ring (Bernstein et al., 1995) (Fig.2). Similarly, a dimer connected by a pair of molecules with S and R configuration via the C—H···O weak interaction can be seen in the compound N-[α-(N-Succimidyl)benzyl]selenamorpholine (Wu et al., 1998). The racemic dimer of I has a symmetric center, leading to the crystal with the centrosymmetric space group, though the individual molecule has chirality. The dimers are further connected into an infinite sheet along the axis a by C—H···N (3.416 (3) Å) weak hydrogen bonds as shown in Fig.3. Though the H-bond length is slightly longer than that of the general C—H···N hydrogen bonds (Berkovitch-Ylellin & Leiserowitz, 1984), it plays a major role in construction of the infinite sheet in I. However, quite a few much longer C—H···N bonds in the centrosymmetric dimers have been discussed, which are considered as an important synthon for the crystal engineering (Marjo et al. 1994; 2001).

The packing diagram of I shown in Fig.4 indicates that the infinite sheets are aligned in the ac plane along the axis a and stacked along the axis b. There are no more significant weak interactions between the sheets.

Related literature

For related literature, see: Allen et al. (1987); Berkovitch-Ylellin & Leiserowitz (1984); Bernstein et al. (1995); Dawood et al. (2005); Fleita et al. (2005); Glusker et al. (1995); Jurčík & Wilhelm (2004); Khrustalev et al. (1998); Marjo et al. (1994, 2001); Wu et al. (1998).

S2. Experimental

2-Amino-1,3,4-thiadiazole (28 mmol, 2.5 g) and benzaldehyde (2.5 ml) were added in a 100 ml round-bottom flask, and 20 ml e thanol as solvent. The mixture was stirred at 80 ° for 1 hr. Then several drops of piperidine were added into the reaction mixture, which was continuously stirred for 3 hrs at 80 °. After reduced pressure distillation and recrystallization, the yellow product (0.088 g, yield 32.16%) was isolated from the solution. IR (KBr, cm^-1): 1618(C=N), 1021(C—N), 3306(N—H). Analysis calculated for C₁₄H₁₈N₄S: C 61.28%, H 6.61%, N 20.42%; Found C 60.75%, H 6.776%, N 20.64%.

S3. Refinement

All the H atoms were treated as riding-model, with N—H=0.86 Å, C—H=0.93–0.98 Å, and their U_iso=1.2U_eq(carrier atom).

Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXTL (Sheldrick, 2001); program(s) used to refine structure: SHELXTL (Sheldrick, 2001); molecular graphics: DIAMOND (Brandenburg, 2001); software used to prepare material for publication: SHELXTL (Sheldrick, 2001).

Figures

	Fig. 1. ORTEP drawing of I with the atom-numbering scheme, showing 50% probability displacement ellipsoids.
	Fig. 2. The centrosymmetric dimer composed by S and R molecules via intermolecular N—H···N hydrogen bonds shown with blue dashed line.
	Fig. 3. Infinite sheets connected by weak intermolecular C—H···N interactions shown with green dashed line.
	Fig. 4. Packing diagram of I viewed along the axis b (hydrogen bonds are shown as dashed lines).

N-[Phenyl(piperidin-1-yl)methyl]-1,3,4-thiadiazol-2-amine

Crystal data

C14H18N4S	F(000) = 1168
Mr = 274.38	Dx = 1.290 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 13043 reflections
a = 19.165 (4) Å	θ = 1.8–28.3°
b = 6.4232 (13) Å	µ = 0.22 mm^−1
c = 23.093 (5) Å	T = 293 K
β = 96.19 (3)°	Block, pale yellow
V = 2826.2 (10) Å^3	0.37 × 0.32 × 0.26 mm
Z = 8

Data collection

Brucker SMART Apex CCD diffractometer	3498 independent reflections
Radiation source: fine-focus sealed tube	2435 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.042
phi and ω scans	θmax = 28.3°, θmin = 1.8°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −25→25
Tmin = 0.923, Tmax = 0.945	k = −8→8
12197 measured reflections	l = −30→30

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)] = 0.053	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.123	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0421P)^2 + 2.0932P] where P = (Fo^2 + 2Fc^2)/3
3498 reflections	(Δ/σ)max < 0.001
172 parameters	Δρmax = 0.30 e Å^−3
0 restraints	Δρmin = −0.31 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
C1	0.04886 (11)	0.7153 (4)	0.02158 (10)	0.0546 (6)
H1	0.0013	0.6832	0.0172	0.066*
C2	0.16299 (9)	0.8538 (3)	0.04207 (8)	0.0355 (4)
C3	0.22536 (9)	1.1632 (3)	0.08492 (8)	0.0358 (4)
H3A	0.2056	1.2599	0.0547	0.043*
C4	0.30084 (10)	1.2265 (3)	0.10260 (8)	0.0357 (4)
C5	0.32101 (11)	1.4303 (4)	0.09465 (9)	0.0458 (5)
H5	0.2888	1.5248	0.0768	0.055*
C6	0.38900 (13)	1.4956 (4)	0.11311 (11)	0.0574 (6)
H6	0.4027	1.6313	0.1060	0.069*
C7	0.43584 (12)	1.3587 (4)	0.14187 (11)	0.0579 (7)
H7	0.4806	1.4035	0.1559	0.069*
C8	0.41645 (11)	1.1554 (4)	0.14985 (10)	0.0562 (6)
H8	0.4486	1.0618	0.1682	0.067*
C9	0.34917 (10)	1.0900 (4)	0.13062 (9)	0.0462 (5)
H9	0.3363	0.9527	0.1366	0.055*
C10	0.15910 (12)	1.3749 (4)	0.14777 (11)	0.0532 (6)
H10A	0.1445	1.4540	0.1128	0.064*
H10B	0.1989	1.4454	0.1687	0.064*
C11	0.09907 (14)	1.3638 (4)	0.18571 (12)	0.0663 (7)
H11A	0.0879	1.5030	0.1981	0.080*
H11B	0.0578	1.3074	0.1631	0.080*
C12	0.11794 (14)	1.2292 (5)	0.23849 (11)	0.0673 (7)
H12A	0.0770	1.2119	0.2594	0.081*
H12B	0.1541	1.2976	0.2643	0.081*
C13	0.14385 (12)	1.0186 (4)	0.22176 (10)	0.0557 (6)
H13A	0.1054	0.9408	0.2013	0.067*
H13B	0.1607	0.9417	0.2566	0.067*
C14	0.20278 (11)	1.0409 (4)	0.18299 (9)	0.0452 (5)
H14A	0.2430	1.1065	0.2047	0.054*
H14B	0.2170	0.9042	0.1708	0.054*
N1	0.09394 (9)	0.6053 (3)	−0.00162 (8)	0.0490 (5)
N2	0.16140 (8)	0.6861 (3)	0.00967 (7)	0.0416 (4)
N3	0.22363 (8)	0.9548 (3)	0.05965 (7)	0.0392 (4)
H3	0.2628	0.8935	0.0558	0.047*
N4	0.17963 (8)	1.1657 (3)	0.13202 (7)	0.0363 (4)
S1	0.08167 (3)	0.92670 (10)	0.06149 (3)	0.0541 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0336 (11)	0.0644 (16)	0.0659 (15)	−0.0092 (11)	0.0054 (10)	−0.0167 (13)
C2	0.0304 (9)	0.0406 (12)	0.0364 (10)	0.0000 (8)	0.0075 (8)	−0.0015 (9)
C3	0.0324 (10)	0.0383 (11)	0.0370 (10)	0.0016 (8)	0.0052 (7)	0.0011 (8)
C4	0.0319 (10)	0.0396 (12)	0.0365 (10)	−0.0016 (8)	0.0076 (8)	−0.0011 (9)
C5	0.0453 (12)	0.0435 (13)	0.0494 (12)	−0.0042 (10)	0.0089 (9)	0.0028 (10)
C6	0.0537 (14)	0.0545 (15)	0.0662 (15)	−0.0178 (12)	0.0161 (12)	−0.0036 (12)
C7	0.0346 (12)	0.080 (2)	0.0605 (15)	−0.0159 (12)	0.0097 (10)	−0.0121 (13)
C8	0.0328 (11)	0.0731 (18)	0.0625 (14)	0.0059 (11)	0.0033 (10)	0.0005 (13)
C9	0.0375 (11)	0.0448 (13)	0.0566 (13)	0.0011 (10)	0.0059 (9)	0.0012 (11)
C10	0.0536 (13)	0.0432 (14)	0.0643 (15)	0.0062 (11)	0.0138 (11)	−0.0052 (11)
C11	0.0590 (15)	0.0577 (17)	0.0864 (19)	0.0124 (13)	0.0276 (14)	−0.0149 (15)
C12	0.0619 (16)	0.084 (2)	0.0593 (15)	−0.0026 (15)	0.0229 (12)	−0.0147 (15)
C13	0.0516 (13)	0.0710 (18)	0.0465 (13)	−0.0033 (12)	0.0135 (10)	0.0045 (12)
C14	0.0405 (11)	0.0532 (14)	0.0422 (11)	0.0046 (10)	0.0051 (9)	0.0040 (10)
N1	0.0367 (9)	0.0574 (13)	0.0535 (11)	−0.0115 (8)	0.0076 (8)	−0.0126 (9)
N2	0.0325 (9)	0.0469 (11)	0.0462 (9)	−0.0061 (8)	0.0079 (7)	−0.0079 (8)
N3	0.0282 (8)	0.0428 (10)	0.0474 (9)	−0.0012 (7)	0.0076 (7)	−0.0098 (8)
N4	0.0327 (8)	0.0370 (10)	0.0397 (9)	0.0038 (7)	0.0066 (7)	−0.0017 (7)
S1	0.0301 (3)	0.0621 (4)	0.0712 (4)	−0.0023 (3)	0.0102 (2)	−0.0233 (3)

Geometric parameters (Å, º)

C1—N1	1.278 (3)	C8—H8	0.9300
C1—S1	1.721 (2)	C9—H9	0.9300
C1—H1	0.9300	C10—N4	1.457 (3)
C2—N2	1.310 (3)	C10—C11	1.521 (3)
C2—N3	1.354 (2)	C10—H10A	0.9700
C2—S1	1.7321 (19)	C10—H10B	0.9700
C3—N3	1.459 (3)	C11—C12	1.506 (4)
C3—N4	1.469 (2)	C11—H11A	0.9700
C3—C4	1.516 (3)	C11—H11B	0.9700
N1—N2	1.392 (2)	C12—C13	1.506 (4)
C3—H3A	0.9800	C12—H12A	0.9700
C4—C5	1.383 (3)	C12—H12B	0.9700
C4—C9	1.384 (3)	C13—C14	1.522 (3)
C5—C6	1.391 (3)	C13—H13A	0.9700
C5—H5	0.9300	C13—H13B	0.9700
C6—C7	1.376 (4)	C14—N4	1.453 (3)
C6—H6	0.9300	C14—H14A	0.9700
C7—C8	1.375 (4)	C14—H14B	0.9700
C7—H7	0.9300	N3—H3	0.8600
C8—C9	1.383 (3)
N1—C1—S1	115.87 (16)	C11—C10—H10A	109.7
C1—S1—C2	86.27 (10)	N4—C10—H10B	109.7
N1—C1—H1	122.1	C11—C10—H10B	109.7
S1—C1—H1	122.1	H10A—C10—H10B	108.2
C1—N1—N2	111.82 (18)	C12—C11—C10	111.3 (2)
C2—N2—N1	112.18 (16)	C12—C11—H11A	109.4
N2—C2—N3	122.09 (17)	C10—C11—H11A	109.4
N2—C2—S1	113.84 (14)	C12—C11—H11B	109.4
N3—C2—S1	124.04 (15)	C10—C11—H11B	109.4
N3—C3—N4	108.45 (15)	H11A—C11—H11B	108.0
N3—C3—C4	109.49 (16)	C11—C12—C13	111.4 (2)
N4—C3—C4	115.22 (15)	C11—C12—H12A	109.3
N3—C3—H3A	107.8	C13—C12—H12A	109.3
N4—C3—H3A	107.8	C11—C12—H12B	109.3
C4—C3—H3A	107.8	C13—C12—H12B	109.3
C5—C4—C9	118.63 (19)	H12A—C12—H12B	108.0
C5—C4—C3	119.38 (18)	C12—C13—C14	110.7 (2)
C9—C4—C3	121.81 (19)	C12—C13—H13A	109.5
C4—C5—C6	120.7 (2)	C14—C13—H13A	109.5
C4—C5—H5	119.6	C12—C13—H13B	109.5
C6—C5—H5	119.6	C14—C13—H13B	109.5
C7—C6—C5	119.7 (2)	H13A—C13—H13B	108.1
C7—C6—H6	120.1	N4—C14—C13	110.32 (17)
C5—C6—H6	120.1	N4—C14—H14A	109.6
C8—C7—C6	120.0 (2)	C13—C14—H14A	109.6
C8—C7—H7	120.0	N4—C14—H14B	109.6
C6—C7—H7	120.0	C13—C14—H14B	109.6
C7—C8—C9	120.1 (2)	H14A—C14—H14B	108.1
C7—C8—H8	120.0	C2—N3—C3	122.75 (16)
C9—C8—H8	120.0	C2—N3—H3	118.6
C8—C9—C4	120.7 (2)	C3—N3—H3	118.6
C8—C9—H9	119.6	C14—N4—C10	111.94 (17)
C4—C9—H9	119.6	C14—N4—C3	116.06 (15)
N4—C10—C11	110.0 (2)	C10—N4—C3	113.18 (17)
N4—C10—H10A	109.7
N3—C3—C4—C5	141.88 (18)	S1—C2—N2—N1	0.0 (2)
N4—C3—C4—C5	−95.6 (2)	C1—N1—N2—C2	0.9 (3)
N3—C3—C4—C9	−43.1 (2)	N2—C2—N3—C3	166.71 (18)
N4—C3—C4—C9	79.4 (2)	S1—C2—N3—C3	−15.3 (3)
C9—C4—C5—C6	1.6 (3)	N4—C3—N3—C2	50.7 (2)
C3—C4—C5—C6	176.75 (19)	C4—C3—N3—C2	177.19 (17)
C4—C5—C6—C7	−2.9 (3)	C13—C14—N4—C10	60.6 (2)
C5—C6—C7—C8	3.1 (4)	C13—C14—N4—C3	−167.42 (18)
C6—C7—C8—C9	−2.0 (4)	C11—C10—N4—C14	−60.0 (2)
C7—C8—C9—C4	0.8 (4)	C11—C10—N4—C3	166.59 (18)
C5—C4—C9—C8	−0.6 (3)	N3—C3—N4—C14	67.3 (2)
C3—C4—C9—C8	−175.6 (2)	C4—C3—N4—C14	−55.8 (2)
N4—C10—C11—C12	55.3 (3)	N3—C3—N4—C10	−161.30 (16)
C10—C11—C12—C13	−52.4 (3)	C4—C3—N4—C10	75.6 (2)
C11—C12—C13—C14	52.5 (3)	N1—C1—S1—C2	1.3 (2)
C12—C13—C14—N4	−56.0 (3)	N2—C2—S1—C1	−0.68 (17)
S1—C1—N1—N2	−1.5 (3)	N3—C2—S1—C1	−178.81 (19)
N3—C2—N2—N1	178.19 (18)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3···N2^i	0.86	2.27	2.999 (2)	143
C1—H1···N1^ii	0.93	2.60	3.416 (3)	147

Symmetry codes: (i) −x+1/2, −y+3/2, −z; (ii) −x, −y+1, −z.