1,4-Dimethyl­piperazine-1,4-diium bis­(hexa­fluoro­phosphate) dihydrate

Sun, S.-W.

doi:10.1107/S1600536812017229

organic compounds

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Volume 68| Part 5| May 2012| Page o1514

doi:10.1107/S1600536812017229

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1,4-Dimethylpiperazine-1,4-diium bis(hexafluorophosphate) dihydrate

Su-Wen Sun ^a ^*

^aCollege of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, People's Republic of China
^*Correspondence e-mail: sunsuwen_5127@163.com

(Received 29 March 2012; accepted 18 April 2012; online 25 April 2012)

In the title hydrated molecular salt, C₆H₁₆N₂⁺·2PF₆⁻·2H₂O, the complete 1,4-dimethylpiperazine-1,4-diium dication is generated by crystallographic inversion symmetry and both C—N bonds are in equatorial orientations. In the crystal, the components are linked by O—H⋯F and N—H⋯O hydrogen bonds but there are no direct links between cations and anions.

Related literature

For background to molecular ferroelectrics, see: Fu et al. (2009 ); Ye et al. (2006 ).

Experimental

Crystal data

C₆H₁₆N₂⁺·2PF₆⁻·2H₂O
M_r = 442.18
Monoclinic, P 2₁ /n
a = 8.1382 (16) Å
b = 6.3666 (13) Å
c = 15.758 (3) Å
β = 99.55 (3)°
V = 805.1 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.40 mm⁻¹
T = 293 K
0.30 × 0.30 × 0.20 mm

Data collection

Rigaku Mercury CCD diffractometer
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005 ) T_min = 0.489, T_max = 1.000
8084 measured reflections
1849 independent reflections
1093 reflections with I > 2σ(I)
R_int = 0.079

Refinement

R[F² > 2σ(F²)] = 0.068
wR(F²) = 0.163
S = 1.06
1849 reflections
122 parameters
3 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.37 e Å⁻³
Δρ_min = −0.36 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯F6ⁱ	0.85 (1)	2.18 (2)	3.008 (5)	167 (5)
O1—H2⋯F3ⁱⁱ	0.84 (1)	2.42 (4)	2.923 (5)	119 (4)
N1—H3⋯O1ⁱⁱⁱ	0.88 (4)	1.98 (4)	2.814 (4)	159 (4)
Symmetry codes: (i) $[-x+{\script{3\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) x, y-1, z.

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812017229/hb6717sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812017229/hb6717Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812017229/hb6717Isup3.cml

checkCIF report

Comment top

Dielectric constant measurements of compounds as a function of temperature is the basic methods to find the materials which possess potential ferroelectric phase changes (Fu et al.,2009;Ye et al.,2006).The dielectric constant of the title compound has been measured, but showed no dielectric disuniformity in the range 120–385 K (mp. 393–402 K)

The asymmetric unit of the title compound is shown in Fig. 1. crystallized in the monoclinic P2(1)/n space group, The crystal packing Fig. 2 features O—H···F and N—H···O hydrogen bonds(O1—H1··· F6, O1—H2···F3, N1—H3···O1) between the C₆H₁₆N₂⁺ cations and PF₆^- anions and H₂O (see; Table 1).

Related literature top

For background to molecular ferroelectrics, see: Fu et al. (2009); Ye et al. (2006).

Experimental top

1,4-Dimethyl-piperazine (0.57 g) and an excess of hexafluorophosphoric acid (0.95 g) were dissolved in methanol without any precipitation under stirring at the ambient temperature. Colourless blocks of the title compound were obtained by slow evaporation at room temperature over two days.

Computing details top

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. T The molecular structure of the title compound, showing the atomic numbering scheme with 30% probability displacement ellipsoids.
	Fig. 2. A view of the packing of the title compound, stacking along the b axis. Dashed lines indicate hydrogen bonds.

1,4-Dimethylpiperazine-1,4-diium bis(hexafluorophosphate) dihydrate top

Crystal data top

C₆H₁₆N₂⁺·2PF₆⁻·2H₂O	Z = 2
M_r = 442.18	F(000) = 448
Monoclinic, P2₁/n	D_x = 1.824 Mg m⁻³
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71073 Å
a = 8.1382 (16) Å	θ = 3.0–27.5°
b = 6.3666 (13) Å	µ = 0.40 mm⁻¹
c = 15.758 (3) Å	T = 293 K
β = 99.55 (3)°	Block, colorless
V = 805.1 (3) Å³	0.30 × 0.30 × 0.20 mm

Data collection top

Rigaku Mercury CCD diffractometer	1849 independent reflections
Radiation source: fine-focus sealed tube	1093 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.079
ω scans	θ_max = 27.5°, θ_min = 3.0°
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	h = −10→10
T_min = 0.489, T_max = 1.000	k = −8→8
8084 measured reflections	l = −20→20

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.068	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.163	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ²(F_o²) + (0.0542P)² + 0.8793P] where P = (F_o² + 2F_c²)/3
1849 reflections	(Δ/σ)_max < 0.001
122 parameters	Δρ_max = 0.37 e Å⁻³
3 restraints	Δρ_min = −0.36 e Å⁻³

Crystal data top

C₆H₁₆N₂⁺·2PF₆⁻·2H₂O	V = 805.1 (3) Å³
M_r = 442.18	Z = 2
Monoclinic, P2₁/n	Mo Kα radiation
a = 8.1382 (16) Å	µ = 0.40 mm⁻¹
b = 6.3666 (13) Å	T = 293 K
c = 15.758 (3) Å	0.30 × 0.30 × 0.20 mm
β = 99.55 (3)°

Data collection top

Rigaku Mercury CCD diffractometer	1849 independent reflections
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	1093 reflections with I > 2σ(I)
T_min = 0.489, T_max = 1.000	R_int = 0.079
8084 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.068	3 restraints
wR(F²) = 0.163	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	Δρ_max = 0.37 e Å⁻³
1849 reflections	Δρ_min = −0.36 e Å⁻³
122 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

	x	y	z	U_iso*/U_eq
P1	0.95245 (13)	0.08087 (17)	0.17417 (6)	0.0411 (3)
F2	0.8739 (4)	0.0534 (5)	0.25799 (19)	0.0871 (10)
F5	1.0375 (4)	0.1087 (5)	0.09153 (17)	0.0832 (10)
F3	0.7745 (3)	0.1086 (5)	0.1178 (2)	0.0921 (11)
F4	0.9416 (4)	−0.1629 (4)	0.1595 (2)	0.0809 (9)
F6	1.1318 (4)	0.0484 (6)	0.22919 (18)	0.0884 (11)
F1	0.9643 (5)	0.3248 (5)	0.1878 (2)	0.1043 (13)
N1	0.1232 (4)	0.0309 (5)	0.4452 (2)	0.0373 (8)
C3	0.1606 (5)	−0.0920 (6)	0.5267 (2)	0.0430 (10)
H3A	0.2412	−0.2008	0.5206	0.052*
H3B	0.2089	0.0001	0.5733	0.052*
C2	−0.0059 (5)	0.1900 (6)	0.4520 (2)	0.0418 (10)
H2A	−0.0324	0.2650	0.3979	0.050*
H2B	0.0370	0.2908	0.4963	0.050*
C1	0.2776 (5)	0.1300 (7)	0.4226 (3)	0.0585 (13)
H1A	0.2493	0.2095	0.3704	0.088*
H1B	0.3561	0.0223	0.4144	0.088*
H1C	0.3262	0.2215	0.4683	0.088*
O1	0.0661 (4)	0.6583 (5)	0.34880 (19)	0.0503 (8)
H1	0.144 (4)	0.639 (9)	0.320 (3)	0.09 (2)*
H2	−0.027 (3)	0.648 (9)	0.317 (3)	0.11 (2)*
H3	0.092 (5)	−0.064 (7)	0.406 (3)	0.050 (12)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
P1	0.0418 (6)	0.0436 (6)	0.0374 (6)	0.0029 (5)	0.0049 (4)	0.0021 (5)
F2	0.106 (3)	0.100 (2)	0.0671 (19)	0.0070 (19)	0.0484 (18)	0.0093 (17)
F5	0.081 (2)	0.123 (3)	0.0512 (17)	0.0102 (18)	0.0271 (15)	0.0156 (16)
F3	0.0463 (17)	0.120 (3)	0.102 (2)	0.0144 (17)	−0.0091 (16)	0.036 (2)
F4	0.091 (2)	0.0488 (17)	0.100 (2)	0.0019 (15)	0.0079 (18)	−0.0138 (15)
F6	0.0546 (18)	0.129 (3)	0.0720 (19)	−0.0122 (17)	−0.0164 (15)	0.0205 (19)
F1	0.141 (3)	0.0461 (19)	0.135 (3)	−0.0075 (18)	0.052 (3)	−0.0085 (18)
N1	0.0398 (19)	0.0371 (19)	0.0347 (18)	−0.0072 (14)	0.0053 (14)	−0.0064 (15)
C3	0.042 (2)	0.043 (2)	0.042 (2)	0.0057 (18)	−0.0009 (17)	0.0016 (18)
C2	0.055 (3)	0.034 (2)	0.036 (2)	0.0004 (18)	0.0031 (18)	0.0050 (17)
C1	0.054 (3)	0.065 (3)	0.060 (3)	−0.023 (2)	0.021 (2)	−0.009 (2)
O1	0.052 (2)	0.0492 (19)	0.0513 (18)	−0.0009 (15)	0.0137 (17)	−0.0023 (14)

Geometric parameters (Å, º) top

P1—F2	1.569 (3)	C3—H3A	0.9700
P1—F4	1.570 (3)	C3—H3B	0.9700
P1—F1	1.569 (3)	C2—C3ⁱ	1.492 (6)
P1—F3	1.578 (3)	C2—H2A	0.9700
P1—F5	1.583 (3)	C2—H2B	0.9700
P1—F6	1.583 (3)	C1—H1A	0.9600
N1—C2	1.476 (5)	C1—H1B	0.9600
N1—C3	1.491 (5)	C1—H1C	0.9600
N1—C1	1.501 (5)	O1—H1	0.845 (10)
N1—H3	0.88 (4)	O1—H2	0.844 (10)
C3—C2ⁱ	1.492 (6)

F2—P1—F4	89.64 (18)	C1—N1—H3	106 (3)
F2—P1—F1	91.11 (18)	C2ⁱ—C3—N1	110.7 (3)
F4—P1—F1	179.25 (19)	C2ⁱ—C3—H3A	109.5
F2—P1—F3	91.30 (19)	N1—C3—H3A	109.5
F4—P1—F3	90.21 (18)	C2ⁱ—C3—H3B	109.5
F1—P1—F3	89.8 (2)	N1—C3—H3B	109.5
F2—P1—F5	178.11 (18)	H3A—C3—H3B	108.1
F4—P1—F5	90.61 (18)	N1—C2—C3ⁱ	111.5 (3)
F1—P1—F5	88.65 (19)	N1—C2—H2A	109.3
F3—P1—F5	90.57 (17)	C3ⁱ—C2—H2A	109.3
F2—P1—F6	89.52 (18)	N1—C2—H2B	109.3
F4—P1—F6	88.61 (18)	C3ⁱ—C2—H2B	109.3
F1—P1—F6	91.4 (2)	H2A—C2—H2B	108.0
F3—P1—F6	178.6 (2)	N1—C1—H1A	109.5
F5—P1—F6	88.61 (17)	N1—C1—H1B	109.5
C2—N1—C3	110.1 (3)	H1A—C1—H1B	109.5
C2—N1—C1	111.3 (3)	N1—C1—H1C	109.5
C3—N1—C1	111.5 (3)	H1A—C1—H1C	109.5
C2—N1—H3	113 (3)	H1B—C1—H1C	109.5
C3—N1—H3	104 (3)	H1—O1—H2	110 (2)

Symmetry code: (i) −x, −y, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···F6ⁱⁱ	0.85 (1)	2.18 (2)	3.008 (5)	167 (5)
O1—H2···F3ⁱⁱⁱ	0.84 (1)	2.42 (4)	2.923 (5)	119 (4)
N1—H3···O1^iv	0.88 (4)	1.98 (4)	2.814 (4)	159 (4)

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

Experimental details

Crystal data
Chemical formula	C₆H₁₆N₂⁺·2PF₆⁻·2H₂O
M_r	442.18
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	293
a, b, c (Å)	8.1382 (16), 6.3666 (13), 15.758 (3)
β (°)	99.55 (3)
V (Å³)	805.1 (3)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.40
Crystal size (mm)	0.30 × 0.30 × 0.20

Data collection
Diffractometer	Rigaku Mercury CCD diffractometer
Absorption correction	Multi-scan (CrystalClear; Rigaku, 2005)
T_min, T_max	0.489, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	8084, 1849, 1093
R_int	0.079
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.068, 0.163, 1.06
No. of reflections	1849
No. of parameters	122
No. of restraints	3
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.37, −0.36

Computer programs: CrystalClear (Rigaku, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···F6ⁱ	0.845 (10)	2.179 (15)	3.008 (5)	167 (5)
O1—H2···F3ⁱⁱ	0.844 (10)	2.42 (4)	2.923 (5)	119 (4)
N1—H3···O1ⁱⁱⁱ	0.88 (4)	1.98 (4)	2.814 (4)	159 (4)

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

Acknowledgements

The author is grateful to the starter fund of Southeast University for financial support to buy the X-ray diffractometer.

References

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