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The title compound, C6H8NO+·H2PO4, consists of 2-(hy­droxy­methyl)­pyridinium and di­hydrogen­phosphate ions. The di­hydrogen­phosphate moieties are linked into chains by pairs of P—O—H...O—P hydrogen bonds. The 2-(hydroxy­methyl)­pyridinium cations are connected to the di­hydrogen­phosphate units by O—H...O and N—H...O hydrogen bonds. Weak π–π interactions help to determine the interchain packing.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103011077/av1139sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270103011077/av1139Isup2.hkl
Contains datablock I

CCDC reference: 217145

Comment top

During the synthesis of metal phosphates templated by organic amines (Cheetham et al., 1999), amine phosphates may occur as unexpected by-products and may also act as intermediates in the formation of open-framework structures (Oliver et al., 1998; Neeraj et al., 1999; Rao et al., 2000). In addition, they show interesting crystal-packing motifs controlled by the interplay of N—H···O and O—H···O hydrogen bonds (Demir et al., 2002). Here we describe the structure of 2-methanolpyridinium dihydrogenphosphate, (C6H8NO)(H2PO4), (I) (Fig. 1).

The pyridine ring is essentially planar (for atoms N1 and C1–C6, the r.m.s. deviation from the best least-squares plane is 0.009 Å), and the bond distances and angles in the cation are comparable to those seen for the neutral molecule coordinated to metal ions (Yilmaz et al., 2002a,b). Similar geometrical parameters were also observed in (C6H8NO)[RuCl3(C6H6NO)(NO)] (Suzuki et al., 1999) in which the organic moiety acts as both an O—H deprotonated (N,O)-ligand to ruthenium and an N—H protonated counter-ion.

For the dihydrogen phosphate group, the protonated P—O vertices (O3 and O4) show their expected lengthening relative to the other P—O bonds (O1 and O2), which are of similar length as a result of delocalization of the negative charge between them.

The crystal packing is shown in Figs. 2 and 3. The dihydrogen phosphate anions are linked by relatively strong, roughly parallel, pairs of P—O—H···O—P and P—O···H—O—P hydrogen bonds, thus creating a polymeric chain that propagates along [001]. Along the chain, these bonds alternate between P—O3—H3···O2—P and P—O2···H3—O2—P pairs, and P—O4—H4···O1—P and P—O1···H4—O4—P pairs. By comparison, in N-(2-hydroxyethyl)-ethylenediammonium hydrogen phosphate monohydrate (Demir et al., 2002), infinite chains of HPO4 groups are linked by a single P—O—H···O—P connection, while in triethanolammonium dihydrogenphosphate (Demir et al., 2003), the [H2PO4] moieties are connected by alternating single and double P—O—H···O—P hydrogen-bond links.

In (I), the 2-methanolpyridinium cations are pendant to the phosphate chains; each (C6H8NO)+ cation is bonded to its neighbouring (H2PO4) unit by both an N1—H1···O1 and an O5—H5···O2 hydrogen bond. The first of these links (Table 2) may be acute because of a weak intramolecular N1—H1···O5 bond [d(N—H) = 0.89 Å, d(H···O) = 2.40 Å, d(N···O) = 2.736 (2) Å and θ(N—H····O) = 103°].

Adjacent chains interact via van der Waals forces and relatively weak ππ ring-stacking interactions [ring–centroid separation = 3.829 Å; the adjacent ring is generated by the symmetry operator (-x, −y, 1 − z)]. The pattern of ππ stacking (Fig. 2) between adjacent chains results in a head-to-tail configuration for the participating 2-methanolpyridinium cations, although it is not clear that the ππ interaction by itself actually drives this motif. This configuration resuls in extended (110) sheets (Fig. 3). If it is not an artefact of crystal packing, a weak C4—H14···O3 bond (Table 2) provides further cohesion between neighbouring chains in the (110) sheets.

Experimental top

H3PO4 (0.814 ml, 12 mmol; aq. 85% wt) was added dropwise to an aqueous solution (20 ml) of ethylene glycol (20%) with 2-methanolpyridine (1.012 ml, 10 mmol) and stirred for 2 h at 323 K. The resulting mixture was left to crystallize at room temperature. The colourless transparent crystals of (I) that resulted from the mixture were washed with a small amount of water and acetone, and dried in air.

Refinement top

Hydroxyl and amine H atoms were found in difference maps and were refined by allowing them to ride in these positions. H atoms bonded to C atoms were placed in calculated positions 0.97 Å from their parent atoms and modelled as riding. The Uiso(H) values were constrained to be 1.2Ueq of the parent atom in all cases.

Computing details top

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97; molecular graphics: ORTEP-3 (Farrugia, 1997) and ATOMS (Dowty, 1999); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The asymmetric unit of (C6H8NO)(H2PO4), with displacement ellipsoids shown at the 50% probability level. H atoms are shown as spheres of arbitrary radii.
[Figure 2] Fig. 2. Part of the structure of (C6H8NO)(H2PO4), showing the connectivity of the dihydrogen phosphate units (yellow tetrahedra) into [001] chains via pairs of O—H···O hydrogen bonds (H···O portion coloured green). Each organic moiety is pendant to a particular [H2PO4] group. Adjacent chains interact via weak ππ stacking interactions (orange lines). [C blue, N green, O red, H grey (sphere radii arbitrary)].
[Figure 3] Fig. 3. The unit-cell packing in (C6H8NO)(H2PO4), viewed along [001]. All H atoms bound to C atoms (except atom H14) have been omitted for clarity. Atom and bond colours are as in Fig. 2, with H14···O3 bonds coloured yellow.
2-(Hydroxymethyl)pyridinium dihydrogenphosphate top
Crystal data top
C6H8NO+·H2O4PZ = 2
Mr = 207.12F(000) = 216
Triclinic, P1Dx = 1.608 Mg m3
a = 7.8826 (4) ÅMo Kα radiation, λ = 0.71073 Å
b = 8.0041 (4) ÅCell parameters from 2793 reflections
c = 8.2092 (5) Åθ = 2.8–30.0°
α = 65.5050 (1)°µ = 0.31 mm1
β = 69.5660 (1)°T = 293 K
γ = 69.0370 (1)°Chunk, colourless
V = 427.67 (4) Å30.39 × 0.37 × 0.28 mm
Data collection top
Bruker SMART1000 CCD
diffractometer
2447 independent reflections
Radiation source: fine-focus sealed tube2150 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.012
ω scansθmax = 30.0°, θmin = 2.8°
Absorption correction: multi-scan
SADABS (Bruker, 1999)
h = 911
Tmin = 0.884, Tmax = 0.918k = 1011
3828 measured reflectionsl = 711
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.039Hydrogen site location: geom and difmap
wR(F2) = 0.115H-atom parameters constrained
S = 1.08 w = 1/[σ2(Fo2) + (0.0759P)2 + 0.0416P]
where P = (Fo2 + 2Fc2)/3
2447 reflections(Δ/σ)max < 0.001
118 parametersΔρmax = 0.44 e Å3
0 restraintsΔρmin = 0.45 e Å3
Crystal data top
C6H8NO+·H2O4Pγ = 69.0370 (1)°
Mr = 207.12V = 427.67 (4) Å3
Triclinic, P1Z = 2
a = 7.8826 (4) ÅMo Kα radiation
b = 8.0041 (4) ŵ = 0.31 mm1
c = 8.2092 (5) ÅT = 293 K
α = 65.5050 (1)°0.39 × 0.37 × 0.28 mm
β = 69.5660 (1)°
Data collection top
Bruker SMART1000 CCD
diffractometer
2447 independent reflections
Absorption correction: multi-scan
SADABS (Bruker, 1999)
2150 reflections with I > 2σ(I)
Tmin = 0.884, Tmax = 0.918Rint = 0.012
3828 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0390 restraints
wR(F2) = 0.115H-atom parameters constrained
S = 1.08Δρmax = 0.44 e Å3
2447 reflectionsΔρmin = 0.45 e Å3
118 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
P10.45065 (4)0.54983 (4)0.24996 (4)0.03134 (12)
O10.31579 (14)0.49693 (16)0.43426 (13)0.0418 (2)
O20.35888 (14)0.68249 (14)0.09334 (13)0.0386 (2)
O30.5794 (2)0.36271 (17)0.21248 (16)0.0627 (4)
H30.59600.33940.11280.075*
O40.58419 (15)0.64905 (16)0.25971 (14)0.0434 (3)
H40.61420.59890.35460.052*
O50.01745 (16)0.26015 (17)0.79348 (16)0.0475 (3)
H50.10260.25730.83540.057*
N10.02109 (16)0.27950 (16)0.45168 (16)0.0365 (2)
H10.06770.35750.50770.044*
C10.0273 (2)0.3218 (2)0.2730 (2)0.0421 (3)
H110.06180.42300.21790.051*
C20.1649 (2)0.2158 (2)0.1728 (2)0.0463 (3)
H120.17160.24490.04900.056*
C30.2941 (2)0.0643 (2)0.2591 (2)0.0492 (4)
H130.38900.00910.19310.059*
C40.2820 (2)0.0222 (2)0.4431 (2)0.0450 (3)
H140.36640.08180.50220.054*
C50.14358 (19)0.13548 (18)0.53948 (19)0.0358 (3)
C60.1239 (2)0.1018 (2)0.7392 (2)0.0454 (3)
H150.06600.00290.81490.054*
H160.24740.06530.76100.054*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
P10.0339 (2)0.03528 (19)0.02256 (17)0.00207 (12)0.00855 (12)0.01146 (13)
O10.0375 (5)0.0597 (6)0.0270 (4)0.0162 (4)0.0073 (4)0.0099 (4)
O20.0399 (5)0.0437 (5)0.0275 (4)0.0023 (4)0.0131 (4)0.0138 (4)
O30.0929 (10)0.0465 (6)0.0406 (6)0.0238 (6)0.0372 (6)0.0239 (5)
O40.0442 (6)0.0541 (6)0.0307 (5)0.0193 (5)0.0113 (4)0.0049 (4)
O50.0411 (6)0.0600 (7)0.0482 (6)0.0098 (5)0.0120 (5)0.0255 (5)
N10.0359 (6)0.0378 (5)0.0339 (5)0.0067 (4)0.0091 (4)0.0116 (4)
C10.0456 (8)0.0418 (7)0.0333 (7)0.0088 (6)0.0112 (6)0.0073 (5)
C20.0547 (9)0.0467 (8)0.0326 (7)0.0135 (6)0.0063 (6)0.0113 (6)
C30.0497 (8)0.0466 (8)0.0465 (8)0.0073 (6)0.0033 (7)0.0216 (7)
C40.0443 (8)0.0372 (7)0.0487 (8)0.0044 (5)0.0140 (6)0.0121 (6)
C50.0377 (6)0.0341 (6)0.0362 (6)0.0116 (5)0.0115 (5)0.0078 (5)
C60.0499 (8)0.0492 (8)0.0390 (7)0.0093 (6)0.0188 (6)0.0123 (6)
Geometric parameters (Å, º) top
P1—O11.5054 (10)C1—C21.368 (2)
P1—O21.5072 (9)C1—H110.9300
P1—O31.5634 (11)C2—C31.385 (2)
P1—O41.5668 (11)C2—H120.9300
O3—H30.8694C3—C41.380 (2)
O4—H40.7908C3—H130.9300
O5—C61.3982 (19)C4—C51.387 (2)
O5—H50.8924C4—H140.9300
N1—C51.3346 (16)C5—C61.506 (2)
N1—C11.3488 (18)C6—H150.9700
N1—H10.8897C6—H160.9700
O1—P1—O2114.29 (6)C3—C2—H12120.6
O1—P1—O3108.06 (7)C4—C3—C2120.03 (15)
O2—P1—O3111.68 (5)C4—C3—H13120.0
O1—P1—O4109.44 (6)C2—C3—H13120.0
O2—P1—O4107.44 (6)C3—C4—C5119.73 (14)
O3—P1—O4105.57 (7)C3—C4—H14120.1
P1—O3—H3123.7C5—C4—H14120.1
P1—O4—H4111.0N1—C5—C4118.41 (13)
C6—O5—H5109.9N1—C5—C6118.60 (13)
C5—N1—C1123.12 (13)C4—C5—C6122.99 (13)
C5—N1—H1121.1O5—C6—C5113.43 (12)
C1—N1—H1115.7O5—C6—H15108.9
N1—C1—C2119.92 (14)C5—C6—H15108.9
N1—C1—H11120.0O5—C6—H16108.9
C2—C1—H11120.0C5—C6—H16108.9
C1—C2—C3118.75 (14)H15—C6—H16107.7
C1—C2—H12120.6
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O2i0.871.672.5386 (14)173
O4—H4···O1ii0.791.782.5667 (14)176
O5—H5···O2iii0.891.832.7071 (15)165
N1—H1···O1iii0.891.892.7172 (16)153
N1—H1···O50.892.402.7358 (16)103
C4—H14···O3iv0.932.523.3472 (19)148
Symmetry codes: (i) x+1, y+1, z; (ii) x+1, y+1, z+1; (iii) x, y+1, z+1; (iv) x+1, y, z+1.

Experimental details

Crystal data
Chemical formulaC6H8NO+·H2O4P
Mr207.12
Crystal system, space groupTriclinic, P1
Temperature (K)293
a, b, c (Å)7.8826 (4), 8.0041 (4), 8.2092 (5)
α, β, γ (°)65.5050 (1), 69.5660 (1), 69.0370 (1)
V3)427.67 (4)
Z2
Radiation typeMo Kα
µ (mm1)0.31
Crystal size (mm)0.39 × 0.37 × 0.28
Data collection
DiffractometerBruker SMART1000 CCD
diffractometer
Absorption correctionMulti-scan
SADABS (Bruker, 1999)
Tmin, Tmax0.884, 0.918
No. of measured, independent and
observed [I > 2σ(I)] reflections
3828, 2447, 2150
Rint0.012
(sin θ/λ)max1)0.703
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.039, 0.115, 1.08
No. of reflections2447
No. of parameters118
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.44, 0.45

Computer programs: SMART (Bruker, 1999), SAINT (Bruker, 1999), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97, ORTEP-3 (Farrugia, 1997) and ATOMS (Dowty, 1999).

Selected bond lengths (Å) top
P1—O11.5054 (10)P1—O31.5634 (11)
P1—O21.5072 (9)P1—O41.5668 (11)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O2i0.871.672.5386 (14)172.7
O4—H4···O1ii0.791.782.5667 (14)175.6
O5—H5···O2iii0.891.832.7071 (15)165.2
N1—H1···O1iii0.891.892.7172 (16)153.0
C4—H14···O3iv0.932.523.3472 (19)147.8
Symmetry codes: (i) x+1, y+1, z; (ii) x+1, y+1, z+1; (iii) x, y+1, z+1; (iv) x+1, y, z+1.
 

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