Ferroelastic n-butyl­ammonium dihydrogen­phosphate

Crystals of n-butyl­ammonium di­hydrogenphosphate, C₄H₉NH₃⁺·H₂PO₄^-, reveal ferroelasticity at room temperature and a number of phase transitions when heated up to approximately 373 K. Some of these phase transitions show hysteresis effects. All atoms except two H atoms exist in pairs linked by the lost symmetry operations derived from the prototypic space group P2/b2₁/n2₁/a. Each of these two different H atoms is involved in an asymmetric hydrogen bond between an oxy­gen pair. Ferroelastic switching is concomitant with jumps of these hydrogen species from donor to acceptor O atoms. The studied structure belongs to the structural family of n-hexyl- to n-decyl­ammonium di­hydrogenphosphates and differs by localization of alternating layers from n-propyl- and n-pentyl­ammonium di­hydrogenphosphates. The studied crystal was slightly twinned; the minor domain constituted approximately 2%.

Computing details

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: JANA98 (Petříček & Dušek, 1998); program(s) used to solve structure: SHELX86 (Sheldrick, 1985); program(s) used to refine structure: JANA2000 (Petříček & Dušek, 2000); molecular graphics: PICTUR (Dušek, 1993); software used to prepare material for publication: JANA98.

n-butylammonium dihydrogenphosphate

Crystal data

C4H9NH3^+H2PO4^−	F(000) = 736
Mr = 171.13	Dx = 1.382 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 9.1481 (9) Å	Cell parameters from 25 reflections
b = 24.877 (2) Å	θ = 13–14°
c = 7.225 (1) Å	µ = 0.30 mm^−1
β = 90.82 (1)°	T = 292 K
V = 1644.0 (4) Å^3	Plate, colourless
Z = 8	0.45 × 0.30 × 0.12 mm

Data collection

Enraf-Nonius CAD-4-MACHIII-PC diffractometer	θmax = 27°
ω–2θ scans	h = −11→11
3844 measured reflections	k = 0→31
3574 independent reflections	l = 0→9
2828 reflections with I > 3σ(I)	3 standard reflections every 3600 min
Rint = 0.008	intensity decay: 2.0%

Refinement

Refinement on F	0 constraints
Least-squares matrix: full with fixed elements per cycle	H atoms treated by a mixture of independent and constrained refinement
R[F > 3σ(F)] = 0.031	w = 1/[σ^2(Fo) + 0.0001(Fo)^2]
wR(F) = 0.042	(Δ/σ)max = 0.01
S = 2.13	Δρmax = 0.47 e Å^−3
3574 reflections	Δρmin = −0.43 e Å^−3
295 parameters	Extinction correction: Becker & Coppens (1974) type I, Lorentz. iso.
42 restraints	Extinction coefficient: 0.000102 (5)

Special details

Refinement. The structure is a superstucture and a ferroelastic structure as well which can be related to the prototypic space group P 2/b 21/n 21/a

The structure was refined as a twin. domain fraction f: calculated from the refinement: 0.022 (4) calculated from 33 pairs of measured intensities of well separated intense reflections (0,0,-4) belonging to each domain. (The intensities of these reflections were collected at different azimuthal angles): 0.023 (1)

The twinning matrix is given in _diffrn_reflns_transf_matrix_ items

The H atoms except of those which are bonded to the O atoms were restrained by the distfix and anglefix functions of JANA2000: The values for distfix were 0.90(0.022) A ng. for N—H distances. The values for distfix were 0.95(0.03) A ng. for methyl-H distances. The values for distfix were 0.95(0.013) A ng. for methylene-H distances. The values for anglefix were 109.4 (1) °.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P1	0.09616 (3)	0.31130 (1)	0.25570 (3)	0.02211 (8)
O11	−0.02452 (9)	0.35502 (3)	0.2316 (1)	0.0366 (3)
O21	0.12834 (8)	0.30119 (3)	0.45762 (9)	0.0328 (2)
O31	0.22298 (7)	0.32869 (3)	0.1409 (1)	0.0316 (2)
O41	0.03056 (8)	0.25712 (3)	0.1798 (1)	0.0323 (2)
P2	0.59217 (3)	0.30782 (1)	0.26224 (3)	0.02258 (8)
O12	0.48010 (9)	0.35479 (3)	0.2623 (1)	0.0362 (3)
O22	0.62777 (9)	0.29711 (3)	0.0537 (1)	0.0358 (2)
O32	0.72505 (7)	0.32664 (3)	0.3659 (1)	0.0338 (2)
O42	0.52538 (8)	0.25686 (3)	0.33826 (9)	0.0305 (2)
N1	0.1798 (1)	0.68108 (4)	0.2670 (1)	0.0303 (3)
C11	0.0939 (1)	0.63077 (5)	0.2473 (2)	0.0339 (3)
C21	0.1884 (1)	0.58152 (5)	0.2530 (2)	0.0392 (4)
C31	0.0989 (2)	0.53041 (6)	0.2444 (2)	0.0557 (5)
C41	0.1873 (2)	0.47947 (6)	0.2484 (3)	0.0712 (7)
N2	0.6888 (1)	0.68074 (4)	0.2279 (1)	0.0292 (3)
C12	0.5990 (1)	0.63154 (5)	0.2477 (2)	0.0337 (3)
C22	0.6903 (1)	0.58153 (5)	0.2457 (2)	0.0386 (4)
C32	0.5977 (2)	0.53107 (6)	0.2545 (2)	0.0557 (5)
C42	0.6833 (2)	0.47948 (6)	0.2513 (3)	0.0703 (7)
H1n1	0.222 (1)	0.6829 (4)	0.377 (1)	0.041 (3)*
H2n1	0.116 (1)	0.7074 (4)	0.251 (1)	0.041 (3)*
H3n1	0.247 (1)	0.6823 (4)	0.179 (1)	0.033 (3)*
H1c11	0.029 (1)	0.6313 (5)	0.348 (1)	0.048 (4)*
H2c11	0.039 (1)	0.6339 (5)	0.136 (1)	0.047 (4)*
H1c21	0.252 (1)	0.5836 (6)	0.149 (1)	0.070 (5)*
H2c21	0.245 (1)	0.5823 (5)	0.365 (1)	0.052 (4)*
H1c31	0.037 (1)	0.5308 (6)	0.347 (1)	0.075 (5)*
H2c31	0.043 (1)	0.5320 (6)	0.135 (1)	0.073 (5)*
H1c41	0.254 (2)	0.4773 (7)	0.147 (2)	0.120 (8)*
H2c41	0.123 (2)	0.4512 (6)	0.241 (2)	0.094 (6)*
H3c41	0.239 (2)	0.4770 (7)	0.359 (2)	0.118 (8)*
H1n2	0.754 (1)	0.6827 (4)	0.322 (1)	0.035 (3)*
H2n2	0.631 (1)	0.7089 (4)	0.231 (1)	0.042 (3)*
H3n2	0.736 (1)	0.6800 (4)	0.122 (1)	0.038 (3)*
H1c12	0.550 (1)	0.6354 (5)	0.361 (1)	0.050 (4)*
H2c12	0.528 (1)	0.6326 (5)	0.149 (1)	0.050 (4)*
H1c22	0.744 (1)	0.5821 (6)	0.134 (1)	0.065 (4)*
H2c22	0.757 (1)	0.5813 (6)	0.350 (1)	0.061 (4)*
H1c32	0.542 (1)	0.5335 (6)	0.362 (1)	0.072 (5)*
H2c32	0.535 (1)	0.5324 (6)	0.151 (1)	0.077 (5)*
H1c42	0.746 (2)	0.4780 (7)	0.354 (2)	0.109 (8)*
H2c42	0.619 (2)	0.4524 (6)	0.258 (2)	0.096 (6)*
H3c42	0.738 (2)	0.4752 (7)	0.144 (2)	0.110 (8)*
HO11	−0.094 (1)	0.3474 (6)	0.275 (2)	0.047 (4)*
HO41	0.027 (2)	0.2529 (5)	0.051 (2)	0.070 (5)*
HO12	0.409 (1)	0.3463 (5)	0.229 (2)	0.047 (4)*
HO22	0.621 (2)	0.2580 (6)	0.019 (2)	0.100 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.0207 (1)	0.0272 (1)	0.0184 (1)	−0.00188 (9)	0.00103 (9)	0.00152 (9)
O11	0.0238 (4)	0.0377 (4)	0.0485 (5)	0.0028 (3)	0.0058 (4)	0.0112 (4)
O21	0.0430 (4)	0.0356 (4)	0.0196 (3)	−0.0047 (3)	−0.0024 (3)	0.0006 (3)
O31	0.0222 (3)	0.0465 (5)	0.0262 (4)	−0.0053 (3)	0.0030 (3)	0.0028 (3)
O41	0.0415 (4)	0.0337 (4)	0.0219 (4)	−0.0110 (3)	0.0024 (3)	−0.0024 (3)
P2	0.0210 (1)	0.0278 (1)	0.0189 (1)	−0.00172 (9)	−0.0007 (1)	−0.00028 (9)
O12	0.0231 (4)	0.0331 (4)	0.0523 (5)	0.0006 (3)	−0.0054 (4)	−0.0061 (4)
O22	0.0549 (5)	0.0330 (4)	0.0198 (3)	−0.0056 (4)	0.0065 (3)	0.0002 (3)
O32	0.0214 (3)	0.0509 (5)	0.0290 (4)	−0.0057 (3)	−0.0030 (3)	−0.0011 (3)
O42	0.0367 (4)	0.0338 (4)	0.0211 (3)	−0.0073 (3)	−0.0010 (3)	0.0035 (3)
N1	0.0303 (5)	0.0318 (5)	0.0289 (5)	0.0040 (4)	0.0003 (4)	0.0015 (4)
C11	0.0302 (6)	0.0387 (6)	0.0329 (6)	−0.0006 (4)	−0.0018 (5)	−0.0025 (5)
C21	0.0385 (6)	0.0342 (6)	0.0448 (7)	−0.0015 (5)	−0.0011 (5)	−0.0006 (5)
C31	0.0557 (9)	0.0419 (8)	0.070 (1)	−0.0122 (6)	0.0005 (8)	−0.0047 (7)
C41	0.105 (1)	0.0332 (8)	0.075 (1)	−0.0068 (8)	−0.002 (1)	−0.0029 (7)
N2	0.0298 (4)	0.0308 (5)	0.0270 (5)	0.0029 (4)	0.0006 (4)	−0.0007 (4)
C12	0.0293 (6)	0.0389 (6)	0.0330 (6)	−0.0029 (4)	0.0029 (5)	0.0025 (5)
C22	0.0380 (6)	0.0342 (6)	0.0436 (7)	−0.0028 (5)	0.0009 (5)	0.0025 (5)
C32	0.0567 (9)	0.0422 (8)	0.068 (1)	−0.0141 (6)	−0.0002 (8)	0.0022 (7)
C42	0.103 (1)	0.0346 (8)	0.073 (1)	−0.0112 (8)	0.003 (1)	0.0018 (7)

Geometric parameters (Å, º)

P1—O11	1.5576 (8)	C31—H1c31	0.94 (1)
P1—O21	1.5052 (7)	C31—H2c31	0.93 (1)
P1—O31	1.4996 (7)	C41—H1c41	0.97 (2)
P1—O41	1.5710 (8)	C41—H2c41	0.91 (2)
P2—O12	1.5546 (8)	C41—H3c41	0.92 (2)
P2—O22	1.5687 (7)	N2—H1n2	0.90 (1)
P2—O32	1.4940 (7)	N2—H2n2	0.88 (1)
P2—O42	1.5138 (7)	N2—H3n2	0.89 (1)
N1—C11	1.484 (1)	C12—H1c12	0.944 (9)
C11—N1	1.484 (1)	C12—H2c12	0.956 (9)
C11—C21	1.500 (2)	C22—H1c22	0.95 (1)
C21—C31	1.513 (2)	C22—H2c22	0.96 (1)
C31—C41	1.503 (2)	C32—H1c32	0.93 (1)
N2—C12	1.482 (1)	C32—H2c32	0.93 (1)
C12—C22	1.498 (2)	C42—H1c42	0.93 (2)
C22—C32	1.516 (2)	C42—H2c42	0.89 (2)
C32—C42	1.504 (2)	C42—H3c42	0.94 (2)
O11—HO11	0.73 (1)	O11—O32^i	2.598 (1)
O41—HO41	0.93 (2)	O21—O22^ii	2.542 (1)
O12—HO12	0.72 (1)	O31—O12	2.582 (1)
O22—HO22	1.01 (2)	O41—O42^iii	2.491 (1)
N1—H1n1	0.88 (1)	O21—N2^iv	2.838 (1)
N1—H2n1	0.88 (1)	O31—N2^v	2.805 (1)
N1—H3n1	0.89 (1)	O41—N2^vi	2.850 (1)
C11—H1c11	0.945 (9)	O22—N1^v	2.980 (1)
C11—H2c11	0.949 (9)	O32—N1^iv	2.786 (1)
C21—H1c21	0.96 (1)	O42—N1^vi	2.760 (1)
C21—H2c21	0.955 (9)
O11—P1—O21	110.69 (4)	O12—P2—O22	105.89 (5)
O11—P1—O31	106.83 (4)	O12—P2—O32	107.23 (4)
O11—P1—O41	107.06 (4)	O12—P2—O42	111.09 (4)
O21—P1—O31	116.24 (4)	O22—P2—O32	110.87 (4)
O21—P1—O41	105.28 (4)	O22—P2—O42	107.26 (4)
O31—P1—O41	110.42 (4)	O32—P2—O42	114.22 (4)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	D···A	D—H···A
N1^v—H3n1^v···O22	0.89 (1)	2.980 (1)	165 (1)
N1^iv—H1n1^iv···O32	0.88 (1)	2.786 (1)	165 (1)
N1^vi—H2n1^vi···O42	0.88 (1)	2.760 (1)	167 (1)
N2^iv—H1n2^iv···O21	0.90 (1)	2.838 (1)	169 (1)
N2^v—H3n2^v···O31	0.89 (1)	2.805 (1)	162 (1)
N2^vi—H2n2^vi···O41	0.88 (1)	2.850 (1)	158 (1)
O11—HO11···O32^i	0.73 (1)	2.598 (1)	175 (1)
O41—HO41···O42^iii	0.93 (2)	2.492 (1)	177 (1)
O12—HO12···O31	0.72 (1)	2.582 (1)	177 (1)
O22^ii—HO22^ii···O21	1.00 (2)	2.542 (1)	174 (2)

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