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In the title compound, 2C10H10N3+·C4O42−·2H2O, the squarate dianion is centrosymmetric. The organic cation shows an unusual, approximately symmetrical, intra­molecular N...H...N hydrogen bond. The other hydrogen bonds are conventional N—H...O and O—H...O links, resulting in chains.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S160053680703139X/hb2459sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S160053680703139X/hb2459Isup2.hkl
Contains datablock I

CCDC reference: 657666

Key indicators

  • Single-crystal X-ray study
  • T = 297 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.043
  • wR factor = 0.122
  • Data-to-parameter ratio = 15.0

checkCIF/PLATON results

No syntax errors found



Alert level A PLAT353_ALERT_3_A Long N-H Bond (0.87A) N1 - H1A ... 1.41 Ang.
Author Response: There is a symmetrical intra-molecular hydrogen bond between the N1 and N3 atoms.

PLAT353_ALERT_3_A Long    N-H Bond (0.87A)   N3     -   H1A    ...       1.28 Ang.
Author Response: There is a symmetrical intra-molecular hydrogen bond between the N1 and N3 atoms.

PLAT771_ALERT_2_A Suspect N-H Bond in CIF:      N1     -H1A     ..       1.41 Ang.
Author Response: There is a symmetrical intra-molecular hydrogen bond between the N1 and N3 atoms.

Alert level C PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low ....... 0.97 PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings Differ .... ? PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ .... ? PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............ 2.00 Ratio
Alert level G PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints ....... 2
3 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 4 ALERT level C = Check and explain 1 ALERT level G = General alerts; check 3 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 4 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

Comment top

Squaric acid, H2Sq, is a very strong dibasic acid and has been studied for potential application to xerographic photoreceptors, organic solar cells and optical recording (Seitz & Imming, 1992; Liebeskind et al., 1993). It is also a useful tool for constructing crystalline architecture because of its rigid and flat four-membered ring framework (Reetz et al., 1994). Squaric acid (H2Sq) can be found in three forms, viz. (a) as uncharged H2Sq, (b) as the HSq- monoanion and (c) as Sq2- dianions on deprotonation by amines. These forms have been observed to crystallize with various types of hydrogen bonding, as summarized by Bertolasi et al. (2001). Our ongoing research on metallic and organic salts of squaric acid (Uçar et al., 2004; Uçar et al., 2005; Köroglu et al., 2005), we have synthesized the title compounds, (I), in which the dianion form of squaric acid is observed.

Each squaric acid molecule donates both its H atoms to the pyridine N atom of two 2,2'dipyridylamine molecules, forming the bis(2,2'dipyridiniumamine) squarate dihydrate salt. The C4O42- anion is centrosymmetric. (Fig. 1). The most noteworthy aspect of the structure of (I) concerns the hydrogen bonding (Table 1). Intermolecular hydrogen bonding is conventional (in terms of geometry), with each of the H atoms being donated. However, the N—H···N intramolecular hydrogen bond associated with the pyridine nitrogen atoms has much more unusual behaviour. The freely refined N—H bond length of 1.28 (2)Å is very long for an N—H covalent bond, which would be expected to be around 0.87Å in an X-ray crystallographic analysis. Consequently, the H···N distance is 1.42 (2) Å, whic is rather short. Given that the overall N···N distance is relatively short at 2.586 (2) Å, these values indicate a strong hydrogen bond, which nevertheles display unusual disorder or thermal motion. A difference Fourier map (Fig. 2; Farrugia, 1999) of the electron density associated with this H atom shows this to be smeared out between the dipyridinium N atoms, with the maximum lying closer to the N3 atom. These type hydrogen bonds have been called "positive charge assisted hydrogen bonds (N+—H···N or N···H—N+)" by Gilli and co-workers [Gilli et al., 1994; Bertolasi et al., 1996; Gilli & Gilli, 2000;] and found in organic amines and carboxylic acids [Steiner et al., 2000; Mathew et al., 2002].

In the crystal of (I), both intermolecular H bonds and van der Waals interactions combine to stabilize the extended structure (Fig. 3). The crystal water molecule and amine nitrogen atom link cations to dianions, acting as hydrogen-bond donors to the squarate oxygen atoms. These interactions mediate the formation of chains in the ac plane (Fig. 3) and adjacent chains are linked by van der Waals interactions.

Related literature top

For related literature, see: Bertolasi et al. (1996, 2001); Farrugia (1999); Gilli & Gilli (2000); Gilli et al. (1994); Köroglu et al. (2005); Liebeskind et al. (1993); Mathew et al. (2002); Reetz et al. (1994); Seitz & Imming (1992); Steiner et al. (2000); Uçar et al. (2004, 2005).

Experimental top

Compound (I) was prepared by mixing squaric acid and 2,2'dipyridilamine in a 1:2 molar ratio in a mixed solution of methanol and water (1:1 v/v, 50 ml), with stirring at 333 K for 1 h. Crystals of (I) were obtained by slow evaporation of the solvent in about a week. The crystals wre filtered off, washed with methanol and dried in vacuo.

Refinement top

H atoms attached to C atoms and amine N atoms were placed in calculated positions (N—H = 0.86 Å, C—H = 0.93 Å) and refined as riding with Uiso(H) = 1.2Ueq(C). The remaining H atoms were located in a difference map. The H atoms of water molecule were refined with the O—H distance restrained to 0.82 (2) Å.

Structure description top

Squaric acid, H2Sq, is a very strong dibasic acid and has been studied for potential application to xerographic photoreceptors, organic solar cells and optical recording (Seitz & Imming, 1992; Liebeskind et al., 1993). It is also a useful tool for constructing crystalline architecture because of its rigid and flat four-membered ring framework (Reetz et al., 1994). Squaric acid (H2Sq) can be found in three forms, viz. (a) as uncharged H2Sq, (b) as the HSq- monoanion and (c) as Sq2- dianions on deprotonation by amines. These forms have been observed to crystallize with various types of hydrogen bonding, as summarized by Bertolasi et al. (2001). Our ongoing research on metallic and organic salts of squaric acid (Uçar et al., 2004; Uçar et al., 2005; Köroglu et al., 2005), we have synthesized the title compounds, (I), in which the dianion form of squaric acid is observed.

Each squaric acid molecule donates both its H atoms to the pyridine N atom of two 2,2'dipyridylamine molecules, forming the bis(2,2'dipyridiniumamine) squarate dihydrate salt. The C4O42- anion is centrosymmetric. (Fig. 1). The most noteworthy aspect of the structure of (I) concerns the hydrogen bonding (Table 1). Intermolecular hydrogen bonding is conventional (in terms of geometry), with each of the H atoms being donated. However, the N—H···N intramolecular hydrogen bond associated with the pyridine nitrogen atoms has much more unusual behaviour. The freely refined N—H bond length of 1.28 (2)Å is very long for an N—H covalent bond, which would be expected to be around 0.87Å in an X-ray crystallographic analysis. Consequently, the H···N distance is 1.42 (2) Å, whic is rather short. Given that the overall N···N distance is relatively short at 2.586 (2) Å, these values indicate a strong hydrogen bond, which nevertheles display unusual disorder or thermal motion. A difference Fourier map (Fig. 2; Farrugia, 1999) of the electron density associated with this H atom shows this to be smeared out between the dipyridinium N atoms, with the maximum lying closer to the N3 atom. These type hydrogen bonds have been called "positive charge assisted hydrogen bonds (N+—H···N or N···H—N+)" by Gilli and co-workers [Gilli et al., 1994; Bertolasi et al., 1996; Gilli & Gilli, 2000;] and found in organic amines and carboxylic acids [Steiner et al., 2000; Mathew et al., 2002].

In the crystal of (I), both intermolecular H bonds and van der Waals interactions combine to stabilize the extended structure (Fig. 3). The crystal water molecule and amine nitrogen atom link cations to dianions, acting as hydrogen-bond donors to the squarate oxygen atoms. These interactions mediate the formation of chains in the ac plane (Fig. 3) and adjacent chains are linked by van der Waals interactions.

For related literature, see: Bertolasi et al. (1996, 2001); Farrugia (1999); Gilli & Gilli (2000); Gilli et al. (1994); Köroglu et al. (2005); Liebeskind et al. (1993); Mathew et al. (2002); Reetz et al. (1994); Seitz & Imming (1992); Steiner et al. (2000); Uçar et al. (2004, 2005).

Computing details top

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing 50% probabilty displacement ellipsoids (arbitrary spheres for the H atoms). Symmetry code: (i) 1 - x, 1 - y, -z. Dashed lines indicate the hydrogen bonds.
[Figure 2] Fig. 2. A difference Fourier map of the electron density associated with the intramolecular N···H···N interaction. The diffuse nature of the electron density is clear, with the largest concentration of electron density located closer to the atom N3 than atom N1.
[Figure 3] Fig. 3. The hydrogen-bonding and van der Waals interactions of (I) in the unit cell (dashed lines indicate the hydrogen bonds).
Bis[2-(2-pyridylamino)pyridinium] squarate dihydrate top
Crystal data top
2C10H10N3+·C4O42·2H2OZ = 1
Mr = 492.50F(000) = 258.0
Triclinic, P1Dx = 1.477 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71069 Å
a = 8.072 (2) ÅCell parameters from 1875 reflections
b = 8.493 (3) Åθ = 2.6–27.8°
c = 8.833 (2) ŵ = 0.11 mm1
α = 74.34 (3)°T = 297 K
β = 87.26 (2)°Block, colourless
γ = 71.85 (4)°0.35 × 0.24 × 0.18 mm
V = 553.6 (3) Å3
Data collection top
Stoe IPDS II
diffractometer
2634 independent reflections
Radiation source: fine-focus sealed tube2027 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.035
Detector resolution: 6.67 pixels mm-1θmax = 28.2°, θmin = 2.6°
ω scansh = 910
Absorption correction: integration
(X-RED32; Stoe & Cie, 2002)
k = 1111
Tmin = 0.947, Tmax = 0.981l = 1111
6024 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.044H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.122 w = 1/[σ2(Fo2) + (0.0672P)2 + 0.0549P]
where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max < 0.001
2634 reflectionsΔρmax = 0.27 e Å3
176 parametersΔρmin = 0.20 e Å3
2 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.079 (12)
Crystal data top
2C10H10N3+·C4O42·2H2Oγ = 71.85 (4)°
Mr = 492.50V = 553.6 (3) Å3
Triclinic, P1Z = 1
a = 8.072 (2) ÅMo Kα radiation
b = 8.493 (3) ŵ = 0.11 mm1
c = 8.833 (2) ÅT = 297 K
α = 74.34 (3)°0.35 × 0.24 × 0.18 mm
β = 87.26 (2)°
Data collection top
Stoe IPDS II
diffractometer
2634 independent reflections
Absorption correction: integration
(X-RED32; Stoe & Cie, 2002)
2027 reflections with I > 2σ(I)
Tmin = 0.947, Tmax = 0.981Rint = 0.035
6024 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0442 restraints
wR(F2) = 0.122H atoms treated by a mixture of independent and constrained refinement
S = 1.02Δρmax = 0.27 e Å3
2634 reflectionsΔρmin = 0.20 e Å3
176 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
C10.1787 (2)0.0003 (2)0.20087 (18)0.0525 (4)
H10.18560.08170.10860.063*
C20.1266 (2)0.1349 (2)0.1916 (2)0.0562 (4)
H20.10190.14680.09420.067*
C30.1108 (2)0.2539 (2)0.3286 (2)0.0518 (4)
H30.07320.34570.32430.062*
C40.15007 (19)0.23637 (18)0.46912 (19)0.0440 (3)
H40.13870.31450.56250.053*
C50.20815 (17)0.09827 (17)0.47064 (16)0.0372 (3)
C60.30437 (17)0.05217 (16)0.63285 (16)0.0367 (3)
C70.3349 (2)0.05677 (19)0.78463 (17)0.0436 (3)
H70.32590.03100.87100.052*
C80.3784 (2)0.1927 (2)0.8039 (2)0.0519 (4)
H80.39750.19900.90480.062*
C90.3944 (2)0.3214 (2)0.6754 (2)0.0535 (4)
H90.42460.41420.68840.064*
C100.3654 (2)0.30938 (19)0.5314 (2)0.0495 (4)
H100.37600.39540.44400.059*
C110.38626 (17)0.57812 (16)0.05777 (14)0.0344 (3)
C120.43433 (18)0.42336 (17)0.07214 (15)0.0371 (3)
N10.22009 (17)0.01827 (15)0.33788 (14)0.0430 (3)
N20.25340 (16)0.07779 (14)0.60874 (13)0.0392 (3)
H2A0.24930.15740.69170.047*
N30.32133 (16)0.17666 (14)0.50969 (14)0.0415 (3)
O10.24748 (14)0.67258 (13)0.12805 (13)0.0494 (3)
O20.35589 (16)0.33000 (16)0.15768 (15)0.0639 (4)
O30.0043 (2)0.4689 (2)0.2011 (2)0.0858 (5)
H3A0.058 (3)0.426 (3)0.163 (3)0.088 (8)*
H3B0.105 (3)0.435 (3)0.171 (3)0.095 (8)*
H1A0.282 (3)0.132 (2)0.392 (2)0.064 (5)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0580 (10)0.0630 (10)0.0364 (7)0.0161 (8)0.0007 (7)0.0158 (7)
C20.0512 (9)0.0726 (11)0.0480 (9)0.0113 (8)0.0037 (7)0.0297 (8)
C30.0442 (8)0.0512 (8)0.0648 (10)0.0109 (7)0.0037 (7)0.0270 (7)
C40.0410 (8)0.0397 (7)0.0498 (8)0.0097 (6)0.0012 (6)0.0125 (6)
C50.0327 (7)0.0379 (7)0.0375 (7)0.0040 (5)0.0010 (5)0.0123 (5)
C60.0325 (6)0.0347 (6)0.0405 (7)0.0050 (5)0.0017 (5)0.0126 (5)
C70.0462 (8)0.0453 (7)0.0390 (7)0.0134 (6)0.0009 (6)0.0116 (6)
C80.0545 (9)0.0564 (9)0.0519 (9)0.0162 (7)0.0005 (7)0.0269 (7)
C90.0591 (10)0.0446 (8)0.0655 (10)0.0202 (7)0.0059 (8)0.0249 (7)
C100.0568 (9)0.0376 (7)0.0554 (9)0.0172 (7)0.0075 (7)0.0124 (6)
C110.0396 (7)0.0343 (6)0.0293 (6)0.0137 (5)0.0012 (5)0.0055 (5)
C120.0409 (7)0.0361 (6)0.0326 (6)0.0146 (5)0.0004 (5)0.0031 (5)
N10.0483 (7)0.0452 (6)0.0355 (6)0.0138 (5)0.0023 (5)0.0116 (5)
N20.0465 (7)0.0348 (6)0.0340 (6)0.0124 (5)0.0001 (5)0.0052 (4)
N30.0472 (7)0.0363 (6)0.0398 (6)0.0117 (5)0.0026 (5)0.0101 (5)
O10.0410 (6)0.0464 (6)0.0497 (6)0.0138 (5)0.0091 (5)0.0074 (4)
O20.0490 (7)0.0599 (7)0.0655 (8)0.0244 (5)0.0033 (5)0.0200 (6)
O30.0617 (9)0.1184 (13)0.1131 (13)0.0447 (9)0.0245 (9)0.0735 (11)
Geometric parameters (Å, º) top
C1—N11.333 (2)C8—C91.380 (2)
C1—C21.358 (3)C8—H80.9300
C1—H10.9300C9—C101.340 (2)
C2—C31.382 (3)C9—H90.9300
C2—H20.9300C10—N31.3441 (19)
C3—C41.353 (2)C10—H100.9300
C3—H30.9300C11—O11.2335 (17)
C4—C51.395 (2)C11—C12i1.4440 (19)
C4—H40.9300C11—C121.4511 (17)
C5—N11.3366 (18)C12—O21.2426 (16)
C5—N21.3596 (18)C12—C11i1.4440 (19)
C6—N31.3323 (18)N1—H1A1.415 (19)
C6—N21.3605 (18)N2—H2A0.8600
C6—C71.388 (2)N3—H1A1.28 (2)
C7—C81.360 (2)O3—H3A0.832 (17)
C7—H70.9300O3—H3B0.834 (17)
N1—C1—C2122.13 (16)C10—C9—H9120.8
N1—C1—H1118.9C8—C9—H9120.8
C2—C1—H1118.9C9—C10—N3121.90 (15)
C1—C2—C3119.11 (15)C9—C10—H10119.0
C1—C2—H2120.4N3—C10—H10119.0
C3—C2—H2120.4O1—C11—C12i134.52 (12)
C4—C3—C2119.71 (15)O1—C11—C12134.30 (13)
C4—C3—H3120.1C12i—C11—C1291.18 (11)
C2—C3—H3120.1O1—C11—C11i179.69 (14)
C3—C4—C5118.45 (15)C12i—C11—C11i45.73 (8)
C3—C4—H4120.8C12—C11—C11i45.45 (8)
C5—C4—H4120.8O2—C12—C11i135.38 (13)
N1—C5—N2117.87 (12)O2—C12—C11135.79 (14)
N1—C5—C4121.56 (13)C11i—C12—C1188.82 (11)
N2—C5—C4120.57 (13)C1—N1—C5118.99 (13)
N3—C6—N2119.44 (13)C1—N1—H1A138.1 (8)
N3—C6—C7120.33 (13)C5—N1—H1A102.9 (8)
N2—C6—C7120.22 (12)C5—N2—C6128.48 (12)
C8—C7—C6118.39 (14)C5—N2—H2A115.8
C8—C7—H7120.8C6—N2—H2A115.8
C6—C7—H7120.8C6—N3—C10120.29 (13)
C7—C8—C9120.69 (15)C6—N3—H1A103.3 (8)
C7—C8—H8119.7C10—N3—H1A136.4 (8)
C9—C8—H8119.7H3A—O3—H3B108 (3)
C10—C9—C8118.38 (14)
N1—C1—C2—C32.0 (3)O1—C11—C12—C11i179.75 (19)
C1—C2—C3—C41.1 (2)C12i—C11—C12—C11i0.0
C2—C3—C4—C50.9 (2)C2—C1—N1—C50.8 (2)
C3—C4—C5—N12.1 (2)N2—C5—N1—C1179.13 (13)
C3—C4—C5—N2178.34 (13)C4—C5—N1—C11.3 (2)
N3—C6—C7—C81.4 (2)N1—C5—N2—C62.9 (2)
N2—C6—C7—C8177.22 (14)C4—C5—N2—C6176.63 (13)
C6—C7—C8—C91.0 (2)N3—C6—N2—C52.9 (2)
C7—C8—C9—C100.3 (3)C7—C6—N2—C5175.82 (13)
C8—C9—C10—N30.1 (3)N2—C6—N3—C10177.57 (13)
O1—C11—C12—O20.8 (3)C7—C6—N3—C101.1 (2)
C12i—C11—C12—O2178.9 (2)C9—C10—N3—C60.3 (2)
C11i—C11—C12—O2178.9 (2)
Symmetry code: (i) x+1, y+1, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2A···O1ii0.861.842.7008 (17)178
O3—H3A···O1iii0.83 (2)2.03 (2)2.8382 (19)163 (2)
N3—H1A···N11.28 (2)1.415 (19)2.5857 (18)147.8 (15)
O3—H3B···O20.83 (2)1.95 (2)2.765 (2)165 (3)
Symmetry codes: (ii) x, y1, z+1; (iii) x, y+1, z.

Experimental details

Crystal data
Chemical formula2C10H10N3+·C4O42·2H2O
Mr492.50
Crystal system, space groupTriclinic, P1
Temperature (K)297
a, b, c (Å)8.072 (2), 8.493 (3), 8.833 (2)
α, β, γ (°)74.34 (3), 87.26 (2), 71.85 (4)
V3)553.6 (3)
Z1
Radiation typeMo Kα
µ (mm1)0.11
Crystal size (mm)0.35 × 0.24 × 0.18
Data collection
DiffractometerStoe IPDS II
Absorption correctionIntegration
(X-RED32; Stoe & Cie, 2002)
Tmin, Tmax0.947, 0.981
No. of measured, independent and
observed [I > 2σ(I)] reflections
6024, 2634, 2027
Rint0.035
(sin θ/λ)max1)0.665
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.044, 0.122, 1.02
No. of reflections2634
No. of parameters176
No. of restraints2
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.27, 0.20

Computer programs: X-AREA (Stoe & Cie, 2002), X-AREA, X-RED32 (Stoe & Cie, 2002), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEPIII (Farrugia, 1997), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2A···O1i0.861.842.7008 (17)178.0
O3—H3A···O1ii0.832 (17)2.031 (18)2.8382 (19)163 (2)
N3—H1A···N11.28 (2)1.415 (19)2.5857 (18)147.8 (15)
O3—H3B···O20.834 (17)1.951 (18)2.765 (2)165 (3)
Symmetry codes: (i) x, y1, z+1; (ii) x, y+1, z.
 

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