2-Amino-1,3-benzothia­zol-3-ium dihydrogen phosphate

The cation of the title compound, C₇H₇N₂S⁺·H₂PO₄⁻, is almost planar (r.m.s deviation = 0.017 Å for all non-H atoms). In the crystal structure, the cations and anions are connected by N—H...O and O—H...O hydrogen bonds, with π–π stacking inter­actions between neighbouring 1,3-thia­zole and benzene rings [centroid–centroid distance = 3.5711 (11) Å], forming a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.038
• wR factor = 0.096
• Data-to-parameter ratio = 16.5

checkCIF/PLATON results

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Alert level C
CRYSC01_ALERT_1_C The word below has not been recognised as a standard
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PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          2
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         21
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          6
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600         13

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          5

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

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
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S1. Comment

In recent years analogues and derivatives of heterocyclic compounds have attracted strong interest due to their useful biological and pharmacological properties. The substituted benzothiazole derivatives have been reported to possess good antibacterial and antifungal activities. Several of its metal complexes have also displayed potent anti-neoplastic, anti-viral and anti-tumour activities (Malik et al., 2010; Sinha & Tiwari, 1986). In the present paper, the structure of 2-amino-1,3-benzothiazol-3-ium dihydrogen phosphate has been determined as part of a research program involving the synthesis and biological evaluation of sulfur containing compounds.

In the cation of the title compound (I), (Fig. 1), the 1,3-benzothiazol-3-ium ring system (S1/N1/C1–C7) is almost planar (r.m.s deviation = 0.002 Å). In the anion, the bond lengths are P1—O1 = 1.5531 (16), P1—O4 = 1.5638 (17), P1—O2 = 1.5017 (12) and P1—O3 = 1.5024 (14) Å. These values are in full agreement with those found in such anions in other organic dihydrogenomonophosphates [Gholivand et al., 2007; Mrad et al., 2009]. The phosphorus atom has a slightly distorted tetrahedral coordination.

In the crystal structure, the cation and anion components are connected by intermolecular N—H···O and O—H···O hydrogen bonds (Table 1, Fig. 2), with π-π stacking interactions between neighbouring 1,3-thiazole and benzene rings [Cg1···Cg2^v= 3.5711 (11) Å; symmetry code: (v) x, 1/2 - y, 1/2 + z; Cg1 and Cg2 are the centroids of the S1/N1/C1/C6/C7 1,3-thiazole and C1–C6 benzene rings, repectively], forming a three-dimensional supramolecular network.

Related literature

For the structural parameters of some organic dihydrogenomonophosphates, see: Gholivand et al. (2007); Mrad et al. (2009). For the biological and pharmacological properties of heterocyclic compounds, see: Malik et al. (2010); Sinha & Tiwari (1986). For the synthesis, see: Thomas et al. (2003).

S2. Experimental

The title compound was synthesized using the method of Thomas et al. (2003), but with few modifications as follows. 0.1 mole of aniline and 9 ml of concentrated hydrochloric acid were taken in a round bottom flask equipped with reflux condenser, as the insoluble white precipitates of aniline hydrochloride were formed, 25 ml of distilled water was added and the reactants were heated for 35 min. After cooling at room temperature 0.1 moles of sodium thiocyanate were added and the mixture was further refluxed and stirred for 5 h. The resulting mixture was then cooled at room temperature and off-white crystalline solid of phenylthiourea separated out.

0.07 moles of phenyl thiourea were dissolved in 70 ml chloroform in a three-necked round bottom flask equipped with reflux condenser, the whole apparatus was fitted in an ice bath. 0.07 M of bromine in 70 ml of chloroform was added drop wise in a period of 2 h in the reaction mixture. The temperature was maintained at 277 K. After the addition of bromine, the mixture was stirred at room temperature for 4 h and was further refluxed for about 3 h until the evolution of hydrogen bromide stopped. On moderate cooling solid separated out filtered and washed with sulfur dioxide water (10 ml conc. H₂SO₄ in 50 ml water). The filtrate was neutralized with aqueous ammonia (25%). Precipitates of 2-aminobenzothiazole separated out. Filtered and washed thoroughly with water and re-crystallized in ethanol.

Then 0.001 moles of 2-aminobenzothiazole in 3 ml of methanol and 1–2 drops of o-phosphoric acid were added in a round bottom flask. The reaction mixture was refluxed for 8–10 h with continuous stirring. On gradual cooling crystalline solid separated out. Filtered and washed the solid with water and recrystallized in methanol to yield the final product.

S3. Refinement

Hydroxyl H atoms and H atoms on N atoms were located in a difference Fourier map and refined as riding in their as-found relative positions, with U_iso(H) = 1.5U_eq(O) and U_iso(H) = 1.2U_eq(N). The distances O—H and N—H were restrained to 0.83 and 0.86 Å, respectively. H atoms bonded to C atoms were positioned geometrically and refined using a riding model, [C—–H = 0.93 Å and U_iso(H) = 1.2U_eq(C)].

Computing details

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2009).

Figures

	Fig. 1. A view of the title molecule. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. Packing diagram viewed down the c axis. Only H atoms involved in hydrogen bonding are shown.

2-Amino-1,3-benzothiazol-3-ium dihydrogen phosphate

Crystal data

C7H7N2S^+·H2PO4^−	F(000) = 512
Mr = 248.20	Dx = 1.622 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2983 reflections
a = 12.3915 (4) Å	θ = 2.6–27.1°
b = 10.1572 (3) Å	µ = 0.47 mm^−1
c = 8.3159 (2) Å	T = 296 K
β = 103.775 (1)°	Rod, off-white
V = 1016.56 (5) Å^3	0.25 × 0.09 × 0.07 mm
Z = 4

Data collection

Bruker APEXII CCD diffractometer	1938 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.033
Graphite monochromator	θmax = 28.3°, θmin = 3.2°
φ and ω scans	h = −13→16
9333 measured reflections	k = −8→13
2490 independent reflections	l = −11→8

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)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.096	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0508P)^2 + 0.1064P] where P = (Fo^2 + 2Fc^2)/3
2490 reflections	(Δ/σ)max = 0.001
151 parameters	Δρmax = 0.31 e Å^−3
5 restraints	Δρmin = −0.26 e Å^−3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement on F² for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating -R-factor-obs 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
S1	0.35481 (4)	0.35955 (5)	1.06135 (6)	0.0400 (2)
N1	0.28028 (14)	0.13298 (14)	0.95775 (19)	0.0362 (5)
N2	0.43880 (16)	0.12254 (17)	1.1731 (2)	0.0460 (6)
C1	0.23286 (16)	0.35055 (18)	0.9039 (2)	0.0363 (6)
C2	0.16650 (19)	0.4518 (2)	0.8240 (3)	0.0494 (7)
C3	0.07398 (19)	0.4193 (2)	0.7023 (3)	0.0555 (8)
C4	0.04759 (19)	0.2898 (2)	0.6589 (3)	0.0525 (7)
C5	0.11376 (17)	0.1882 (2)	0.7386 (2)	0.0436 (6)
C6	0.20561 (15)	0.22026 (17)	0.8625 (2)	0.0340 (6)
C7	0.36161 (16)	0.18903 (19)	1.0689 (2)	0.0350 (5)
P1	0.31052 (4)	0.78446 (4)	0.06814 (5)	0.0321 (2)
O1	0.21014 (12)	0.72357 (14)	0.12333 (17)	0.0448 (5)
O2	0.26558 (12)	0.87196 (11)	−0.07803 (14)	0.0396 (4)
O3	0.38850 (12)	0.84982 (13)	0.21213 (15)	0.0441 (4)
O4	0.37402 (14)	0.66563 (15)	0.01419 (16)	0.0497 (5)
H1	0.271 (2)	0.0479 (16)	0.948 (3)	0.0600*
H2	0.18390	0.53930	0.85170	0.0590*
H3	0.02810	0.48600	0.64790	0.0670*
H4	−0.01510	0.27070	0.57560	0.0630*
H5	0.09680	0.10090	0.70950	0.0520*
H6	0.4904 (18)	0.164 (2)	1.242 (3)	0.0600*
H7	0.430 (2)	0.0391 (17)	1.184 (3)	0.0600*
H8	0.228 (2)	0.690 (3)	0.214 (2)	0.0750*
H9	0.379 (2)	0.663 (3)	−0.080 (2)	0.0750*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0424 (3)	0.0331 (3)	0.0412 (3)	−0.0075 (2)	0.0035 (2)	−0.0034 (2)
N1	0.0421 (9)	0.0296 (8)	0.0326 (8)	−0.0059 (7)	0.0007 (7)	0.0004 (6)
N2	0.0446 (10)	0.0425 (9)	0.0417 (10)	−0.0074 (8)	−0.0079 (8)	0.0031 (8)
C1	0.0357 (10)	0.0384 (10)	0.0352 (9)	−0.0013 (8)	0.0092 (8)	−0.0010 (8)
C2	0.0530 (13)	0.0418 (11)	0.0525 (12)	0.0090 (10)	0.0110 (10)	0.0023 (10)
C3	0.0512 (13)	0.0605 (14)	0.0515 (13)	0.0172 (11)	0.0055 (10)	0.0062 (11)
C4	0.0370 (11)	0.0749 (16)	0.0409 (11)	0.0027 (11)	0.0000 (9)	0.0000 (10)
C5	0.0400 (11)	0.0500 (11)	0.0383 (10)	−0.0081 (9)	0.0043 (8)	−0.0034 (9)
C6	0.0347 (10)	0.0382 (10)	0.0290 (9)	−0.0026 (8)	0.0074 (7)	0.0013 (7)
C7	0.0371 (10)	0.0350 (9)	0.0321 (9)	−0.0055 (8)	0.0068 (8)	0.0006 (7)
P1	0.0371 (3)	0.0314 (3)	0.0236 (2)	0.0020 (2)	−0.0009 (2)	0.0029 (2)
O1	0.0399 (8)	0.0585 (9)	0.0308 (7)	−0.0073 (7)	−0.0021 (6)	0.0036 (6)
O2	0.0562 (9)	0.0307 (6)	0.0256 (6)	0.0059 (6)	−0.0027 (6)	0.0010 (5)
O3	0.0462 (8)	0.0503 (8)	0.0292 (7)	−0.0127 (6)	−0.0038 (6)	0.0042 (6)
O4	0.0685 (10)	0.0476 (8)	0.0334 (7)	0.0263 (7)	0.0128 (7)	0.0122 (7)

Geometric parameters (Å, º)

S1—C1	1.7504 (19)	N2—H7	0.862 (18)
S1—C7	1.735 (2)	N2—H6	0.86 (2)
P1—O3	1.5024 (14)	C1—C6	1.389 (3)
P1—O1	1.5531 (16)	C1—C2	1.384 (3)
P1—O2	1.5017 (12)	C2—C3	1.377 (3)
P1—O4	1.5638 (17)	C3—C4	1.382 (3)
O1—H8	0.809 (19)	C4—C5	1.385 (3)
O4—H9	0.801 (17)	C5—C6	1.380 (3)
N1—C6	1.386 (2)	C2—H2	0.9300
N1—C7	1.323 (2)	C3—H3	0.9300
N2—C7	1.314 (3)	C4—H4	0.9300
N1—H1	0.873 (16)	C5—H5	0.9300
S1···O4^i	3.1497 (16)	C1···C7^xi	3.547 (3)
S1···N1	2.5519 (16)	C1···C5^iii	3.469 (3)
S1···O3^ii	3.2897 (15)	C4···C6^xi	3.496 (3)
S1···C5^iii	3.664 (2)	C5···S1^xi	3.664 (2)
S1···C6^iii	3.5429 (18)	C5···C1^xi	3.469 (3)
P1···O2^iv	3.5032 (13)	C6···C4^iii	3.496 (3)
P1···H6^v	2.87 (2)	C6···C7^xi	3.577 (3)
P1···H8^vi	2.890 (16)	C6···S1^xi	3.5429 (18)
P1···H9^iv	2.896 (17)	C7···C6^iii	3.577 (3)
P1···H1^vii	2.857 (17)	C7···C1^iii	3.547 (3)
P1···H7^vii	3.02 (2)	C3···H3^xii	3.0400
O1···O2^iv	2.6017 (18)	C3···H5^xiii	3.0300
O2···N1^vii	2.6693 (18)	C5···H3^xiv	3.0000
O2···P1^vi	3.5032 (13)	H1···P1^x	2.857 (17)
O2···O1^vi	2.6017 (18)	H1···O2^x	1.800 (16)
O3···N2^vii	2.875 (2)	H1···H7	2.43 (3)
O3···S1^v	3.2897 (15)	H2···O4^i	2.7400
O3···N2^v	3.138 (2)	H2···O1^i	2.8900
O3···O4^iv	2.5654 (18)	H3···C5^xiii	3.0000
O4···S1^viii	3.1497 (16)	H3···H3^xii	2.4100
O4···O3^vi	2.5654 (18)	H3···H5^xiii	2.4600
O4···N2^v	3.076 (2)	H3···C3^xii	3.0400
O1···H4^ix	2.6300	H4···O1^xv	2.6300
O1···H2^viii	2.8900	H5···H3^xiv	2.4600
O2···H8^vi	1.795 (18)	H5···C3^xiv	3.0300
O2···H1^vii	1.799 (16)	H6···O4^ii	2.31 (2)
O3···H7^vii	2.018 (18)	H6···O3^ii	2.39 (2)
O3···H9^iv	1.765 (17)	H6···P1^ii	2.87 (2)
O3···H6^v	2.39 (2)	H7···O3^x	2.018 (18)
O4···H6^v	2.31 (2)	H7···H1	2.43 (3)
O4···H2^viii	2.7400	H7···P1^x	3.02 (2)
N1···O2^x	2.6693 (18)	H8···P1^iv	2.890 (16)
N1···S1	2.5519 (16)	H8···O2^iv	1.795 (19)
N2···O3^ii	3.138 (2)	H9···P1^vi	2.896 (17)
N2···O4^ii	3.076 (2)	H9···O3^vi	1.765 (17)
N2···O3^x	2.875 (2)
C1—S1—C7	90.04 (9)	C1—C2—C3	118.06 (19)
O2—P1—O4	109.85 (7)	C2—C3—C4	121.6 (2)
O3—P1—O4	107.32 (8)	C3—C4—C5	120.5 (2)
O1—P1—O2	107.83 (8)	C4—C5—C6	118.07 (19)
O1—P1—O3	110.41 (8)	C1—C6—C5	121.24 (17)
O1—P1—O4	105.70 (8)	N1—C6—C1	112.22 (15)
O2—P1—O3	115.33 (7)	N1—C6—C5	126.55 (17)
P1—O1—H8	112.5 (18)	N1—C7—N2	123.59 (18)
P1—O4—H9	118 (2)	S1—C7—N1	112.46 (13)
C6—N1—C7	114.70 (15)	S1—C7—N2	123.95 (15)
C7—N1—H1	123.5 (16)	C3—C2—H2	121.00
C6—N1—H1	121.7 (16)	C1—C2—H2	121.00
H6—N2—H7	120 (2)	C4—C3—H3	119.00
C7—N2—H6	119.8 (14)	C2—C3—H3	119.00
C7—N2—H7	119.0 (17)	C3—C4—H4	120.00
C2—C1—C6	120.50 (18)	C5—C4—H4	120.00
S1—C1—C6	110.54 (13)	C4—C5—H5	121.00
S1—C1—C2	128.96 (15)	C6—C5—H5	121.00
C7—S1—C1—C2	178.1 (2)	S1—C1—C2—C3	179.72 (17)
C7—S1—C1—C6	−1.63 (15)	C6—C1—C2—C3	−0.5 (3)
C1—S1—C7—N2	−178.14 (18)	C2—C1—C6—N1	−178.75 (18)
C1—S1—C7—N1	1.89 (15)	C2—C1—C6—C5	1.6 (3)
C6—N1—C7—N2	178.35 (18)	C1—C2—C3—C4	−0.5 (4)
C7—N1—C6—C5	−179.97 (19)	C2—C3—C4—C5	0.6 (4)
C7—N1—C6—C1	0.4 (2)	C3—C4—C5—C6	0.5 (3)
C6—N1—C7—S1	−1.7 (2)	C4—C5—C6—C1	−1.5 (3)
S1—C1—C6—N1	1.0 (2)	C4—C5—C6—N1	178.86 (19)
S1—C1—C6—C5	−178.61 (15)

Symmetry codes: (i) x, y, z+1; (ii) −x+1, y−1/2, −z+3/2; (iii) x, −y+1/2, z+1/2; (iv) x, −y+3/2, z+1/2; (v) −x+1, y+1/2, −z+3/2; (vi) x, −y+3/2, z−1/2; (vii) x, y+1, z−1; (viii) x, y, z−1; (ix) −x, y+1/2, −z+1/2; (x) x, y−1, z+1; (xi) x, −y+1/2, z−1/2; (xii) −x, −y+1, −z+1; (xiii) −x, y+1/2, −z+3/2; (xiv) −x, y−1/2, −z+3/2; (xv) −x, y−1/2, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O2^x	0.873 (16)	1.800 (16)	2.6693 (18)	174 (3)
N2—H6···O3^ii	0.86 (2)	2.39 (2)	3.138 (2)	147 (2)
N2—H6···O4^ii	0.86 (2)	2.31 (2)	3.076 (2)	149.3 (19)
N2—H7···O3^x	0.862 (18)	2.018 (18)	2.875 (2)	172 (2)
O1—H8···O2^iv	0.809 (19)	1.795 (19)	2.6017 (18)	175 (3)
O4—H9···O3^vi	0.801 (17)	1.765 (17)	2.5654 (18)	178 (3)

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