A second polymorph of 2-amino­pyridinium di­hydrogenphosphate

In the title compound, β-C₅H₇N₂⁺·H₂PO₄⁻, the tetra­hedral dihydrogenphosphate moieties are linked into double chains by O—H⋯O hydrogen bonds, and the organic species cross­link the chains into sheets by way of N—H⋯O bonds. The resulting structure is quite different from that of the previously described α polymorph of this stoichiometry [Czapla, Dacko & Waskowska (2003). J. Phys. Condens. Matter, 15, 3793–3803].

Comment

Ammonium phosphates can function as inter­mediates or by-products in the formation of open-framework metal phosphates templated by organic amines (Oliver et al., 1998; Neeraj et al., 1999; Rao et al., 2000). They show inter­esting crystal packing motifs, strongly influenced by the inter­play of N—H⋯O and O—H⋯O hydrogen bonds (Demir et al., 2002). We describe here the structure of the title compound, β-(C₅H₇N₂)(H₂PO₄), (I) (Fig. 1), which was obtained accidentally in the hydro­thermal preparation of a 2-amino­pyridinium-templated zincophosphate at 443 K. Compound (I) is a polymorph of a quite different structure of the same stoichiometry (Czapla et al., 2003), hereafter denoted α-(C₅H₇N₂)(H₂PO₄).

In the tetra­hedral dihydrogenphosphate group in (I), the protonated P—O vertices (O1 and O2) show the expected lengthening (Table 1) relative to the other P—O bonds (O3 and O4), which are of similar length as a result of delocalization of the negative charge between them. The pyridine ring is essentially planar (for atoms N1 and C1–C5 the r.m.s. deviation from the least-squares plane is 0.004 Å) and its bond distances and angles are normal.

The crystal packing in (I) is shown in Figs. 2 and 3. In addition to electrostatic forces, hydrogen bonds appear to be a key factor in establishing this structure. The dihydrogen­phos­phate anions are linked into double chains by way of P—O—H⋯O—P bonds (Table 2), such that every anion acts as a donor for two hydrogen bonds and an acceptor for two hydrogen bonds. In graph-set notation (Bernstein et al., 1995), an R₃³(12) loop arises for every triplet of connected tetra­hedra. The P1⋯P1ⁱ and P1⋯P1ⁱⁱ separations are 4.5260 (14) and 4.5357 (17) Å, respectively (see Table 2 for symmetry codes). The chains propagate along [010], generated by the 2₁ screw axis.

(Di)hydrogen­phos­phate chains can show a surprising variety of hydrogen-bonding motifs. In N-(2-hydroxy­ethyl)­ethyl­ene­di­ammonium hydrogen­phos­phate mono­hydrate (Demir et al., 2002), infinite chains of HPO₄²⁻ groups are linked by single P—O—H⋯O—P connections, whilst 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 1,3-diam­inium hydrogenphosphate hydrate (Kamoun et al., 1991), single phosphate/water chains occur, whereas 1,3-diaminium bis­(di­hydrogen­phosphate) (Kamoun et al., 1992; Marsh, 2004) contains a double tetra­hedral chain different from that seen in (I), in which the fundamental symmetry is that of inversion.

In (I), the organic species inter­acts with the inorganic chains by way of three N—H⋯O bonds. Two of these bonds are to a single adjacent H₂PO₄⁻ tetra­hedron, and the third is to a similar species displaced in the a direction. These inter­actions result in (001) sheets that inter­act with each other by van der Waals forces. In contrast to the distinctive π–π stacking inter­actions between closely associated pairs of 2-amino­pyridinium rings in the zincophosphate framework {(C₅H₇N₂)[Zn(HPO₄)(H₂PO₄)]·H₂O}_n, synthesized at room temperature (Yilmaz et al., 2005), there are no significant π–π stacking forces in (I).

The structure of (I) is quite different from that of α-(C₅H₇N₂)(H₂PO₄) (Czapla et al., 2003), which contains a three-dimensional supramolecular array of H₂PO₄⁻ groups encapsulating the organic moieties in pseudo-channels in space group C2/c. In addition to one well defined P—O—H⋯O—P hydrogen bond, α-(C₅H₇N₂)(H₂PO₄) contains two short [2.469 (2) and 2.471 (2) Å] inversion-symmetry-generated pairs of O atoms with which the other dihydrogen­phos­phate H atoms are associated. These could represent symmetric O⋯H⋯O bonds (i.e. the H atom occupying the inversion centre) or disordered O—H⋯O and O⋯H—O bonds (i.e. a double potential well with the H atom shifted away from the inversion centre). The H atoms associated with the short O⋯O pairs were not located in the X-ray study, but on the basis of the physical properties of α-(C₅H₇N₂)(H₂PO₄), Czapla et al. (2003) suggested that a double potential well was more likely. α-(C₅H₇N₂)(H₂PO₄) shows a ferroelectric to paraelectric phase transition at 104 K, which is probably associated with rearrangements of the H atoms. We are now investigating this system further to try to clarify this situation.

Although the connectivities of the dihydrogenphosphate tetra­hedra are completely different, the α and β forms of (C₅H₇N₂)(H₂PO₄) both contain three similar N—H⋯O inter­actions [for the α form, mean H⋯O = 2.02 Å and mean N⋯O = 2.882 (2) Å; for the β form, mean H⋯O = 1.98 Å and mean N⋯O = 2.849 (6) Å]. The β form is slightly more dense than the α form (ρ = 1.580 and 1.557 Mg m⁻³, respectively), perhaps suggesting that it is the more stable form, even though a visual comparison of the structures suggests that van der Waals inter­actions are more prevalent in the β form.

Figure 1 A view of (I), showing 50% probability displacement ellipsoids. Hydrogen bonds are indicated by dashed bonds.

Figure 2 A detail of (I) in a polyhedral representation, showing the connectivity of the dihydrogenphosphate units into [010] chains by way of O—H⋯O hydrogen bonds (H⋯O portion shaded). Symmetry codes are as in Table 2.

Figure 3 A view down [010] of the unit-cell packing in (I). O—H⋯O and N—H⋯O hydrogen bonds are shown with the H⋯O portion shaded.

Experimental

A 0.41 ml aliquot of H₃PO₄ (6 mmol, aqueous, 85 wt%) was mixed with an aqueous suspension (10 ml) of ZnO (0.163 g, 2 mmol) and a clear solution was obtained. An aqueous solution (10 ml) of 2-amino­pyridine (0.188 g, 2 mmol) was added to this solution dropwise. The resulting mixture was transferred to a 45 ml Teflon-lined stainless steel reaction vessel, heated at 443 K for 60 h and then cooled to room temperature. Colourless crystals of (I) were isolated by vacuum filtration, washed with a small amount of water and dried in air. All crystals obtained were of the β form (yield 38%). Direct reaction of phospho­ric acid and 2-amino­pyridine in the absence of ZnO yields the α polymorph, as reported by Czapla et al. (2003).

Crystal data

• C₅H₇N₂⁺·H₂PO₄⁻

• M_r = 192.11

• Monoclinic, P 2₁

• a = 9.0502 (12) Å

• b = 4.5260 (3) Å

• c = 9.9697 (11) Å

• β = 98.576 (4)°

• V = 403.80 (7) ų

• Z = 2

• D_x = 1.580 Mg m⁻³

• Mo Kα radiation

• Cell parameters from 928 reflections

• θ = 2.9–27.5°

• μ = 0.32 mm⁻¹

• T = 120 (2) K

• Rod, colourless

• 0.32 × 0.08 × 0.06 mm

Data collection

• Nonius KappaCCD diffractometer

• ω and φ scans

• Absorption correction: multi-scan(SADABS; Bruker, 2003)T_min = 0.905, T_max = 0.978

• 3961 measured reflections

• 1719 independent reflections

• 1206 reflections with I > 2σ(I)

• R_int = 0.090

• θ_max = 27.6°

• h = −11 → 11

• k = −5 → 5

• l = −10 → 13

Refinement

• Refinement on F²

• R[F² > 2σ(F²)] = 0.060

• wR(F²) = 0.137

• S = 1.03

• 1719 reflections

• 116 parameters

• H-atom parameters constrained

• w = 1/[σ²(F_o²) + (0.0472P)² + 0.0857P] where P = (F_o² + 2F_c²)/3

• (Δ/σ)_max < 0.001

• Δρ_max = 0.36 e Å⁻³

• Δρ_min = −0.44 e Å⁻³

• Extinction correction: SHELXL97

• Extinction coefficient: 0.061 (11)

• Absolute structure: Flack (1983), 672 Friedel pairs

• Flack parameter: 0.3 (2)

Table 1
Selected interatomic distances (Å)

P1—O3	1.514 (3)
P1—O4	1.521 (3)
P1—O1	1.552 (3)
P1—O2	1.560 (4)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O4^i	0.80 (3)	1.83 (4)	2.544 (4)	149 (5)
O2—H2⋯O3^ii	0.86 (3)	1.69 (3)	2.552 (5)	174 (5)
N1—H7⋯O3	0.88	1.82	2.676 (5)	165
N2—H8⋯O4	0.88	2.08	2.963 (5)	179
N2—H9⋯O4^iii	0.88	2.05	2.908 (5)	166
Symmetry codes: (i) x, y+1, z; (ii) ; (iii) .

The O-bound H atoms were found in difference maps and their positions were refined with the O—H distance restrained to 0.82 (4) Å. Other H atoms were placed in idealized locations (C—H = 0.95 Å and N—H = 0.88 Å) and refined as riding atoms. The constraint U_iso(H) = 1.2U_eq(carrier) was applied in all cases. The refined value of the Flack (1983) parameter was not definitive. A refinement of the opposite (inverted) absolute structure gave a value of 0.6 (2).

Data collection: COLLECT (Nonius, 1998); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and ATOMS (Shape Software, 2002); software used to prepare material for publication: SHELXL97.

Supporting information

S1. Comment

Ammonium phosphates can function as intermediates or by-products in the formation of open-framework metal phosphates templated by organic amines (Oliver et al., 1998; Neeraj et al., 1999; Rao et al., 2000). They show interesting crystal packing motifs, strongly influenced by the interplay of N—H···O and O—H···O hydrogen bonds (Demir et al., 2002). We describe here the structure of the title compound, β-(C₅H₇N₂)(H₂PO₄), (I) (Fig. 1), which was obtained accidentally in the hydrothermal preparation of a 2-aminopyridinium-templated zincophosphate at 443 K. Compound (I) is a polymorph of a quite different structure of the same stoichiometry (Czapla et al., 2003), hereafter known as α-(C₅H₇N₂)(H₂PO₄).

In the tetrahedral dihydrogenphosphate group in (I), the protonated P—O vertices (O1 and O2) show the expected lengthening (Table 1) relative to the other P—O bonds (O3 and O4), which are of similar length as a result of delocalization of the negative charge between them. The pyridine ring is essentially planar (for atoms N1 and C1–C5, the r.m.s. deviation from the least-squares plane is 0.004 Å), and its bond distances and angles are normal.

The crystal packing in (I) is shown in Figs. 2 and 3. In addition to electrostatic forces, hydrogen bonds appear to be a key factor in establishing this structure. The dihydrogenphosphate anions are linked into double chains by way of P—O—H···O—P bonds (Table 2), such that every anion acts as a donor for two hydrogen bonds and an acceptor for two hydrogen bonds. In graph-set notation (Bernstein et al., 1995), an R³₃(12) loop arises for every triplet of connected tetrahedra. The P1···P1ⁱ (see Table 2 for symmetry code) and P1···P1ⁱⁱ separations are 4.5260 (14) and 4.5357 (17) Å, respectively. The chains propagate along [010], generated by the 2₁ screw axis.

(Di)hydrogenphosphate chains can show a surprising variety of hydrogen-bonding motifs. In N-(2-hydroxyethyl)ethylenediammonium hydrogenphosphate monohydrate (Demir et al., 2002), infinite chains of HPO₄²⁻ groups are linked by single P—O—H···O—P connections, whilst 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 1,3-diaminium hydrogenphosphate hydrate (Kamoun et al., 1991), single phosphate/water chains occur, whereas in 1,3-diaminium bis(dihydrogenphosphate) (Kamoun et al., 1992; Marsh, 2004), a different kind of double tetrahedral chain arises from the one seen in (I), in which the fundamental symmetry is that of inversion.

In (I), the organic species interacts with the inorganic chains by way of three N—H···O bonds. Two of these bonds are to a single adjacent H₂PO₄⁻ tetrahedron, and the third is to a similar species displaced in the a direction. These interactions result in (001) sheets that interact with each other by van der Waals forces. In contrast to the distinctive π–π stacking interactions between closely associated pairs of 2-aminopyridinium rings in the zincophosphate framework {(C₅H₇N₂)[Zn(HPO₄)(H₂PO₄)]^.H₂O}_n, synthesized at room temperature (Yilmaz et al., 2005), there are no significant π–π stacking forces in (I).

The structure of (I) is quite different from that of α-(C₅H₇N₂)(H₂PO₄) (Czapla et al., 2003), which contains a three-dimensional supramolecular array of H₂PO₄⁻ groups encapsulating the organic moieties in pseudo-channels in space group C2/c. In addition to one well defined P—O—H···O—P hydrogen bond, α-(C₅H₇N₂)(H₂PO₄) contains two short [2.469 (2) and 2.471 (2) Å] inversion-symmetry-generated pairs of O atoms with which the other dihydrogenphosphate H atoms are associated. These could represent symmetric O···H···O bonds (i.e. the H atom occupying the inversion centre), or disordered O—H···O and O···H—O bonds (i.e. a double potential well with the H atom shifted away from the inversion centre). The H atoms associated with the short O···O pairs were not located in the X-ray study, but on the basis of the physical properties of α-(C₅H₇N₂)(H₂PO₄), Czapla et al. (2003) suggested that a double potential well was more likely. α-(C₅H₇N₂)(H₂PO₄) shows a ferroelectric to paraelectric phase transition at 104 K, which is probably associated with rearrangements of the H atoms. We are now investigating this system further to try to clarify this situation.

Although the connectivities of the dihydrogenphosphate tetrahedra are completely different, the α and β forms of (C₅H₇N₂)(H₂PO₄) both contain three similar N—H···O interactions [for the α form, mean H···O = 2.02 Å and mean N···O = 2.882 (2) Å; for the β form, mean H···O = 1.98 Å and mean N···O = 2.849 (6) Å]. β-(C₅H₇N₂)(H₂PO₄) is slightly more dense than α-(C₅H₇N₂)(H₂PO₄) (ρ = 1.580 and 1.557 Mg m⁻³, respectively), perhaps suggesting that it is the more stable form, even though a visual comparison of the structures suggests that van der Waals interactions are more prevalent in the β form.

S2. Experimental

A 0.41 ml aliquot of H₃PO₄ (6 mmol) (aqueous, 85 wt%) was mixed with an aqueous suspension (10 ml) of ZnO (0.163 g, 2 mmol) and a clear solution was obtained. An aqueous solution (10 ml) of 2-aminopyridine (0.188 g, 2 mmol) was added to this solution dropwise. The resulting mixture was transferred to a 45 ml Teflon-lined stainless steel reaction vessel, heated at 443 K for 60 h and then cooled to room temperature. Colorless crystals of (I) were isolated by vacuum filtration. They were washed with a small amount of water and dried in air. All crystals obtained were of the β form. Yield 38%. Direct reaction of phosphoric acid and 2-aminopyridine in the absence of ZnO yields the α polymorph, as reported by Czapla et al. (2003).

S3. Refinement

The O-bound H atoms were found in difference maps and their positions were refined with the O—H distance restrained to 0.82 (4) Å. Other H atoms were placed in idealized locations (C—H = 0.95 Å and N—H = 0.88 Å) and refined as riding atoms. The constraint U_iso(H) = 1.2U_eq(carrier) was applied in all cases. The refined value of the Flack (1983) parameter was not definitive. A refinement of the opposite (inverted) absolute structure gave a value of 0.6 (2).

Computing details

Data collection: Collect (Nonius, 1998); cell refinement: HKL SCALEPACK (Otwinowski & Minor 1997); data reduction: HKL DENZO (Otwinowski & Minor 1997) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and ATOMS (Shape Software, 2002); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. A view of (I), showing 50% probability displacement ellipsoids. Hydrogen bonds are indicated by dashed lines.
	Fig. 2. A detail of (I) in a polyhedral representation, showing the connectivity of the dihydrogenphosphate units into [010] chains by way of O—H···O hydrogen bonds (H···O portion shaded). Symmetry codes as in Table 2.
	Fig. 3. A view down [010] of the unit cell packing in (I). O—H···O and N—H···O hydrogen bonds are shown with the H···O portion shaded.

β-2-aminopyridinium dihydrogenphosphate

Crystal data

C5H7N2^+·H2O4P^−	F(000) = 200
Mr = 192.11	Dx = 1.580 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 928 reflections
a = 9.0502 (12) Å	θ = 2.9–27.5°
b = 4.5260 (3) Å	µ = 0.32 mm^−1
c = 9.9697 (11) Å	T = 120 K
β = 98.576 (4)°	Rod, colourless
V = 403.80 (7) Å^3	0.32 × 0.08 × 0.06 mm
Z = 2

Data collection

Nonius KappaCCD diffractometer	1719 independent reflections
Radiation source: fine-focus sealed tube	1206 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.090
ω and ϕ scans	θmax = 27.6°, θmin = 3.3°
Absorption correction: multi-scan (SADABS; Bruker, 2003)	h = −11→11
Tmin = 0.905, Tmax = 0.978	k = −5→5
3961 measured reflections	l = −10→13

Refinement

Refinement on F^2	Hydrogen site location: difmap (O-H) and geom (others)
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.060	w = 1/[σ^2(Fo^2) + (0.0472P)^2 + 0.0857P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.137	(Δ/σ)max < 0.001
S = 1.03	Δρmax = 0.36 e Å^−3
1719 reflections	Δρmin = −0.44 e Å^−3
116 parameters	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
3 restraints	Extinction coefficient: 0.061 (11)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 672 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.3 (2)

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
P1	0.30651 (14)	0.5428 (2)	0.38054 (11)	0.0208 (3)
O1	0.2446 (4)	0.7884 (6)	0.2788 (3)	0.0262 (9)
H1	0.197 (6)	0.919 (9)	0.305 (5)	0.031*
O2	0.4496 (4)	0.4371 (7)	0.3245 (3)	0.0267 (8)
H2	0.517 (5)	0.350 (11)	0.381 (5)	0.032*
O3	0.3440 (4)	0.6596 (7)	0.5238 (3)	0.0239 (8)
O4	0.1919 (4)	0.2952 (6)	0.3713 (3)	0.0228 (8)
C1	0.3557 (6)	0.4974 (12)	0.8620 (5)	0.0324 (13)
H3	0.4380	0.6249	0.8568	0.039*
C2	0.3210 (7)	0.4233 (12)	0.9850 (6)	0.0359 (14)
H4	0.3769	0.4976	1.0662	0.043*
C3	0.1992 (6)	0.2325 (11)	0.9883 (5)	0.0328 (14)
H5	0.1722	0.1772	1.0733	0.039*
C4	0.1186 (6)	0.1248 (12)	0.8716 (5)	0.0362 (14)
H6	0.0366	−0.0041	0.8755	0.043*
C5	0.1588 (6)	0.2075 (9)	0.7446 (5)	0.0227 (11)
N1	0.2752 (5)	0.3933 (8)	0.7461 (4)	0.0249 (10)
H7	0.3002	0.4498	0.6681	0.030*
N2	0.0882 (5)	0.1089 (8)	0.6266 (4)	0.0288 (10)
H8	0.1177	0.1651	0.5503	0.035*
H9	0.0120	−0.0126	0.6247	0.035*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.0279 (7)	0.0180 (5)	0.0169 (6)	0.0000 (6)	0.0044 (5)	0.0007 (5)
O1	0.041 (2)	0.0169 (15)	0.0199 (19)	0.0072 (15)	0.0026 (17)	0.0010 (13)
O2	0.027 (2)	0.0339 (17)	0.0205 (19)	0.0081 (14)	0.0092 (16)	0.0065 (14)
O3	0.028 (2)	0.0269 (15)	0.0169 (18)	−0.0057 (14)	0.0026 (15)	−0.0006 (12)
O4	0.030 (2)	0.0150 (14)	0.025 (2)	−0.0006 (14)	0.0092 (16)	−0.0023 (12)
C1	0.036 (3)	0.035 (3)	0.024 (3)	−0.002 (3)	−0.002 (2)	−0.003 (2)
C2	0.044 (4)	0.043 (3)	0.019 (3)	0.010 (3)	0.002 (3)	0.003 (2)
C3	0.029 (3)	0.048 (3)	0.024 (3)	0.014 (3)	0.014 (3)	0.012 (2)
C4	0.037 (4)	0.041 (3)	0.034 (3)	0.005 (2)	0.017 (3)	0.012 (2)
C5	0.022 (3)	0.021 (2)	0.026 (3)	0.002 (2)	0.006 (2)	0.0027 (18)
N1	0.029 (3)	0.0294 (19)	0.018 (2)	0.0030 (19)	0.0091 (19)	0.0022 (17)
N2	0.031 (3)	0.031 (2)	0.026 (2)	−0.0086 (18)	0.0082 (19)	−0.0025 (17)

Geometric parameters (Å, º)

P1—O3	1.514 (3)	C2—H4	0.9500
P1—O4	1.521 (3)	C3—C4	1.367 (8)
P1—O1	1.552 (3)	C3—H5	0.9500
P1—O2	1.560 (4)	C4—C5	1.418 (7)
O1—H1	0.80 (3)	C4—H6	0.9500
O2—H2	0.86 (3)	C5—N2	1.329 (6)
C1—C2	1.352 (7)	C5—N1	1.346 (6)
C1—N1	1.356 (6)	N1—H7	0.8800
C1—H3	0.9500	N2—H8	0.8800
C2—C3	1.405 (8)	N2—H9	0.8800
O3—P1—O4	111.69 (18)	C4—C3—H5	119.3
O3—P1—O1	112.02 (18)	C2—C3—H5	119.3
O4—P1—O1	108.15 (19)	C3—C4—C5	119.4 (5)
O3—P1—O2	111.32 (19)	C3—C4—H6	120.3
O4—P1—O2	110.34 (18)	C5—C4—H6	120.3
O1—P1—O2	102.9 (2)	N2—C5—N1	119.4 (4)
P1—O1—H1	119 (4)	N2—C5—C4	123.2 (5)
P1—O2—H2	117 (4)	N1—C5—C4	117.3 (5)
C2—C1—N1	121.3 (5)	C5—N1—C1	123.1 (4)
C2—C1—H3	119.4	C5—N1—H7	118.4
N1—C1—H3	119.4	C1—N1—H7	118.4
C1—C2—C3	117.6 (5)	C5—N2—H8	120.0
C1—C2—H4	121.2	C5—N2—H9	120.0
C3—C2—H4	121.2	H8—N2—H9	120.0
C4—C3—C2	121.3 (5)
N1—C1—C2—C3	0.5 (8)	C3—C4—C5—N1	−0.7 (7)
C1—C2—C3—C4	0.1 (8)	N2—C5—N1—C1	−178.1 (4)
C2—C3—C4—C5	0.0 (8)	C4—C5—N1—C1	1.3 (7)
C3—C4—C5—N2	178.8 (5)	C2—C1—N1—C5	−1.3 (7)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O4^i	0.80 (3)	1.83 (4)	2.544 (4)	149 (5)
O2—H2···O3^ii	0.86 (3)	1.69 (3)	2.552 (5)	174 (5)
N1—H7···O3	0.88	1.82	2.676 (5)	165
N2—H8···O4	0.88	2.08	2.963 (5)	179
N2—H9···O4^iii	0.88	2.05	2.908 (5)	166

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