6-(4-Hydroxy­benzyl­amino)purin-3-ium chloride: a protonated form of para-topoline

The structure of the title compound, C₁₂H₁₂N₅O⁺·Cl⁻, comprises a 6-(4-hydroxy­benzyl­amino)purinium cation and a chloride anion. The cation exists as the N3-H tautomer. Inter­molecular N—H...N hydrogen bonds connect cations into centrosymmetric dimers, with an N...N distance of 2.821 (2) Å. Furthermore, the secondary structure is stabilized by O—H...Cl and N—H...Cl hydrogen bonds, weak nonbonding inter­atomic contacts of the types C—H...Cl [3.1652 (4) Å] and C—H...C [2.897 (2) Å], and π–π stacking inter­actions [3.357 (4) Å].

Key indicators

• Single-crystal X-ray study
• T = 110 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.030
• wR factor = 0.082
• Data-to-parameter ratio = 12.1

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.93
PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent .....          ?

Alert level G
ABSTM02_ALERT_3_G  When printed, the submitted absorption T values will be
            replaced by the scaled T values. Since the ratio of scaled T's
            is identical to the ratio of reported T values, the scaling
            does not imply a change to the absorption corrections used in
            the study.
            Ratio of Tmax expected/reported      0.925
            Tmax scaled      0.925 Tmin scaled      0.861

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 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

The structure of the title compound (I) was determined within the framework of our systematic crystallographic investigations of plant growth hormones, called cytokinins, derived from 6-benzylaminopurine (Trávníček et al., 1997, 2004, 2005; Trávníček & Matiková-Maľarová, 2006; and Maloň et al., 2001, 2002).

The molecular structure of (I) contains a 6-(4-hydroxybenzylamino)purinium cation and a chloride anion (Fig. 1). The cation exists as the N3-protonated N7 tautomer and contains three different aromatic ring systems, i.e. benzene, pyrimidine and imidazole. Each of these deviates slightly from planarity, with maximum deviations from the least-squares planes being 0.005 (2) Å for C12, 0.007 (2) Å for C2 and 0.002 (2) Å for C8 (Brandenburg, 2006). The dihedral angle between benzene ring and purine skeleton is 65.32 (4)°, whilst the pyrimidine and imidazole rings are nearly co-planar with their dihedral angle being only 0.61 (4)A%. The interatomic parameters in (I) are comparable to those found for similar N3-protonated N7 tautomers of 6-benzylaminopurine derivatives (Trávníček et al. 2004). The N-H···N hydrogen bonds connect two cations into centrosymmetric dimers in the bc plane (Fig. 2, Table 1). The cations and chloride anions are connected via hydrogen bonds of the type N-H···Cl and O-H···Cl (Fig. 2 and 3). Moreover, π-π stacking interactions between purine rings of neighbouring molecules [C5···C8ⁱⁱⁱ = 3.357 (4) Å; symmetry code: (iii) -1+x, y, z] together with the C—H···Cl and C—H···C contacts contribute to the stabilization of the secondary structure (Fig. 3) [C8···Cl1^iv = 3.1652 (4) Å, C9···C6^v = 2.897 (2) Å; symmetry codes: (iv) 1-x, 1-y, 1-z; (v) 1+x, y, z].

Related literature

For similar structures of the protonated forms of aromatic cytokinins derived from 6-benzylaminopurine, see: Maloň et al. (2001, 2002); Trávníček et al. (1997, 2004, 2005); Trávníček & Matiková-Maľarová (2006).

S2. Experimental

A few colorless crystals of the title compound (I) were obtained from the mother liquor, as a by-product, during the synthesis of a Ru complex under acidic conditions (conc. HCl).

S3. Refinement

All H atoms of were located in difference maps and refined using a riding model, with C–H distances = 0.95–0.99 Å and N–H = 0.88 Å, and with U_iso(H) = 1.2U_eq(C,N). The O–H atom was refined freely.

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2002); cell refinement: CrysAlis RED (Oxford Diffraction, 2002); data reduction: CrysAlis RED (Oxford Diffraction, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997) and DIAMOND (Brandenburg, 2006).

Figures

	Fig. 1. A view of the molecular structure of (I) showing atom labelling. Non-H atoms are drawn with the 50% probability displacement ellipsoids.
	Fig. 2. Part of the crystal structure of (I), viewed along the a axis, showing the hydrogen bonding as dashed lines.
	Fig. 3. Part of the crystal structure of (I), viewed along the c axis, showing non-bonding and π-stacking interactions (dashed lines). Most of the H-atoms have been omitted for clarity.

6-(4-Hydroxybenzylamino)purin-3-ium chloride

Crystal data

C12H12N5O^+·Cl^−	F(000) = 576
Mr = 277.72	Dx = 1.513 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 10605 reflections
a = 4.2503 (1) Å	θ = 3.0–31.9°
b = 25.5022 (7) Å	µ = 0.31 mm^−1
c = 11.3995 (3) Å	T = 110 K
β = 99.457 (3)°	Prism, colourless
V = 1218.82 (5) Å^3	0.40 × 0.35 × 0.25 mm
Z = 4

Data collection

Oxford Diffraction Xcalibur2 CCD diffractometer	2132 independent reflections
Radiation source: Enhance (Mo) X-ray Source	2034 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.009
Detector resolution: 8.361 pixels mm^-1	θmax = 25.0°, θmin = 3.0°
rotation method, ω scans	h = −4→5
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2002)	k = −30→30
Tmin = 0.931, Tmax = 1.000	l = −13→13
10101 measured reflections

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)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.082	H atoms treated by a mixture of independent and constrained refinement
S = 1.16	w = 1/[σ^2(Fo^2) + (0.0385P)^2 + 0.7626P] where P = (Fo^2 + 2Fc^2)/3
2132 reflections	(Δ/σ)max < 0.001
176 parameters	Δρmax = 0.29 e Å^−3
0 restraints	Δρmin = −0.17 e Å^−3

Special details

Experimental. Absorption correction: CrysAlis RED (Oxford Diffraction) empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.

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
O1	0.4740 (3)	0.12382 (4)	0.66975 (11)	0.0232 (3)
Cl1	0.36116 (9)	0.412050 (15)	0.42073 (3)	0.02078 (14)
N1	0.9597 (3)	0.37404 (5)	0.85376 (12)	0.0175 (3)
N3	0.7284 (3)	0.43903 (5)	0.96037 (12)	0.0176 (3)
H3A	0.7130	0.4535	1.0293	0.021*
N6	0.8406 (3)	0.36780 (5)	0.64812 (11)	0.0160 (3)
H6A	0.7363	0.3799	0.5805	0.019*
N7	0.3877 (3)	0.46270 (5)	0.66656 (11)	0.0166 (3)
H7A	0.3524	0.4572	0.5893	0.020*
N9	0.3541 (3)	0.49887 (5)	0.84217 (12)	0.0174 (3)
C2	0.9189 (4)	0.39766 (6)	0.95251 (14)	0.0188 (3)
H2A	1.0344	0.3843	1.0247	0.023*
C4	0.5601 (4)	0.45766 (6)	0.85696 (14)	0.0161 (3)
C5	0.5878 (4)	0.43435 (6)	0.75049 (13)	0.0154 (3)
C6	0.7962 (4)	0.39114 (6)	0.74745 (14)	0.0153 (3)
C8	0.2564 (4)	0.50041 (6)	0.72518 (14)	0.0183 (3)
H8A	0.1091	0.5256	0.6871	0.022*
C9	1.0543 (4)	0.32272 (6)	0.64404 (14)	0.0172 (3)
H9A	1.2364	0.3258	0.7101	0.021*
H9B	1.1404	0.3238	0.5685	0.021*
C10	0.8926 (4)	0.27056 (6)	0.65340 (14)	0.0162 (3)
C11	0.9549 (4)	0.24111 (6)	0.75725 (14)	0.0193 (3)
H11A	1.0938	0.2547	0.8241	0.023*
C12	0.8174 (4)	0.19219 (6)	0.76476 (14)	0.0197 (3)
H12A	0.8646	0.1723	0.8359	0.024*
C13	0.6111 (4)	0.17244 (6)	0.66816 (14)	0.0177 (3)
C14	0.5451 (4)	0.20129 (6)	0.56378 (14)	0.0189 (3)
H14A	0.4039	0.1878	0.4973	0.023*
C15	0.6868 (4)	0.24985 (6)	0.55734 (14)	0.0176 (3)
H15A	0.6422	0.2694	0.4856	0.021*
H1W	0.467 (6)	0.1153 (10)	0.739 (2)	0.044 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0367 (7)	0.0164 (6)	0.0162 (6)	−0.0072 (5)	0.0040 (5)	0.0014 (5)
Cl1	0.0259 (2)	0.0208 (2)	0.0155 (2)	0.00258 (15)	0.00303 (16)	−0.00167 (14)
N1	0.0188 (7)	0.0159 (7)	0.0181 (7)	0.0002 (5)	0.0040 (5)	0.0001 (5)
N3	0.0213 (7)	0.0174 (7)	0.0146 (6)	0.0007 (5)	0.0041 (5)	−0.0017 (5)
N6	0.0183 (7)	0.0141 (6)	0.0158 (6)	0.0002 (5)	0.0031 (5)	−0.0008 (5)
N7	0.0210 (7)	0.0145 (6)	0.0140 (6)	−0.0001 (5)	0.0021 (5)	0.0000 (5)
N9	0.0207 (7)	0.0137 (6)	0.0182 (7)	0.0011 (5)	0.0041 (5)	−0.0010 (5)
C2	0.0199 (8)	0.0186 (8)	0.0179 (8)	0.0001 (6)	0.0032 (6)	0.0013 (6)
C4	0.0172 (8)	0.0143 (8)	0.0174 (8)	−0.0031 (6)	0.0050 (6)	−0.0009 (6)
C5	0.0166 (8)	0.0137 (8)	0.0162 (8)	−0.0033 (6)	0.0032 (6)	−0.0001 (6)
C6	0.0150 (8)	0.0130 (7)	0.0184 (8)	−0.0046 (6)	0.0042 (6)	0.0001 (6)
C8	0.0208 (8)	0.0135 (8)	0.0206 (8)	0.0014 (6)	0.0035 (6)	0.0006 (6)
C9	0.0175 (8)	0.0155 (8)	0.0198 (8)	0.0012 (6)	0.0064 (6)	−0.0023 (6)
C10	0.0158 (8)	0.0153 (8)	0.0187 (8)	0.0027 (6)	0.0068 (6)	−0.0022 (6)
C11	0.0216 (8)	0.0191 (8)	0.0162 (8)	0.0011 (6)	0.0001 (6)	−0.0033 (6)
C12	0.0269 (9)	0.0174 (8)	0.0146 (8)	0.0032 (6)	0.0028 (6)	0.0027 (6)
C13	0.0217 (8)	0.0147 (8)	0.0178 (8)	0.0010 (6)	0.0067 (6)	−0.0009 (6)
C14	0.0221 (8)	0.0194 (8)	0.0146 (7)	−0.0008 (6)	0.0012 (6)	−0.0022 (6)
C15	0.0210 (8)	0.0173 (8)	0.0149 (7)	0.0021 (6)	0.0039 (6)	0.0022 (6)

Geometric parameters (Å, º)

O1—C13	1.371 (2)	C4—C5	1.374 (2)
O1—H1W	0.83 (3)	C5—C6	1.418 (2)
N1—C2	1.313 (2)	C8—H8A	0.9500
N1—C6	1.366 (2)	C9—C10	1.509 (2)
N3—C2	1.342 (2)	C9—H9A	0.9900
N3—C4	1.360 (2)	C9—H9B	0.9900
N3—H3A	0.8800	C10—C15	1.389 (2)
N6—C6	1.320 (2)	C10—C11	1.390 (2)
N6—C9	1.4708 (19)	C11—C12	1.386 (2)
N6—H6A	0.8800	C11—H11A	0.9500
N7—C8	1.343 (2)	C12—C13	1.385 (2)
N7—C5	1.377 (2)	C12—H12A	0.9500
N7—H7A	0.8800	C13—C14	1.388 (2)
N9—C8	1.331 (2)	C14—C15	1.384 (2)
N9—C4	1.360 (2)	C14—H14A	0.9500
C2—H2A	0.9500	C15—H15A	0.9500
C13—O1—H1W	109.3 (17)	N7—C8—H8A	123.5
C2—N1—C6	119.64 (14)	N6—C9—C10	113.33 (12)
C2—N3—C4	117.00 (13)	N6—C9—H9A	108.9
C2—N3—H3A	121.5	C10—C9—H9A	108.9
C4—N3—H3A	121.5	N6—C9—H9B	108.9
C6—N6—C9	123.76 (13)	C10—C9—H9B	108.9
C6—N6—H6A	118.1	H9A—C9—H9B	107.7
C9—N6—H6A	118.1	C15—C10—C11	118.24 (15)
C8—N7—C5	106.86 (13)	C15—C10—C9	120.98 (14)
C8—N7—H7A	126.6	C11—C10—C9	120.74 (14)
C5—N7—H7A	126.6	C12—C11—C10	121.04 (15)
C8—N9—C4	103.62 (13)	C12—C11—H11A	119.5
N1—C2—N3	125.74 (15)	C10—C11—H11A	119.5
N1—C2—H2A	117.1	C13—C12—C11	119.76 (14)
N3—C2—H2A	117.1	C13—C12—H12A	120.1
N9—C4—N3	127.83 (14)	C11—C12—H12A	120.1
N9—C4—C5	111.82 (14)	O1—C13—C12	122.22 (14)
N3—C4—C5	120.35 (14)	O1—C13—C14	117.67 (14)
C4—C5—N7	104.70 (13)	C12—C13—C14	120.08 (15)
C4—C5—C6	120.17 (14)	C15—C14—C13	119.43 (15)
N7—C5—C6	135.12 (14)	C15—C14—H14A	120.3
N6—C6—N1	119.58 (14)	C13—C14—H14A	120.3
N6—C6—C5	123.32 (14)	C14—C15—C10	121.44 (14)
N1—C6—C5	117.09 (14)	C14—C15—H15A	119.3
N9—C8—N7	113.00 (14)	C10—C15—H15A	119.3
N9—C8—H8A	123.5

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N6—H6A···Cl1	0.88	2.36	3.2262 (14)	168
N7—H7A···Cl1	0.88	2.25	3.0709 (13)	156
N3—H3A···N9^i	0.88	1.96	2.8209 (18)	166
O1—H1W···Cl1^ii	0.83 (3)	2.30 (3)	3.1151 (13)	170 (2)

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