Neutron structures of ammonium tetrafluoroberyllate

Srivastava, R.C.; Klooster, W.T.; Koetzle, T.F.

doi:10.1107/S010876819800737X

Neutron structures of ammonium tetrafluoroberyllate

R. C. Srivastava, W. T. Klooster and T. F. Koetzle

It is thought that hydrogen bonding is responsible for the ferroelectricity in ammonium tetrafluoroberyllate, (NH $_{4}$ ) $_{2}$ BeF $_{4}$ . In the past X-ray data have been collected, but these did not permit accurate determination of the H-atom positions. In order to obtain more accurate information the neutron structures have now been determined for the paraelectric and ferroelectric phases. Going from the paraelectric to the ferroelectric phase, both the BeF $_4^{2-}$ and the NH

ions rotate and shift from the mirror planes of the paraelectric phase. This results in removal of the mirror-plane symmetry and formation of a superlattice with the a axis doubled. Along the polar c axis, the NH

ions move towards the BeF $_4^{2-}$ ions within chains of molecules and the chains move slightly relative to one another. The rotations and translations give rise to stronger hydrogen-bonding interactions.

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Supporting information

	Crystallographic Information File (CIF) Contains datablocks global, I, II, III
	Structure factor file (CIF format) Contains datablock I
	Structure factor file (CIF format) Contains datablock 2
	Structure factor file (CIF format) Contains datablock 3
	Portable Document Format (PDF) file Supplementary material

Computing details top

For all compounds, data collection: local; cell refinement: local; data reduction: local; program(s) used to refine structure: UPALS (Lundgren, 1982).

Figures top

(I) ammonium tetrafluoroberyllate top

Crystal data top

(NH₄)₂BeF₄	D_x = 1.748 Mg m⁻³
M_r = 121.09	Neutron radiation, λ = 1.0462 Å
Orthorhombic, Pnma	Cell parameters from 32 reflections
Hall symbol: -P 2ac 2n	θ = 20–27°
a = 7.531 (3) Å	µ = 0.29 mm⁻¹
b = 5.874 (2) Å	T = 200 K
c = 10.399 (4) Å	Box, colorless
V = 460.0 (5) Å³	4.0 × 3.9 × 3.9 mm
Z = 4

Data collection top

Beamline H6M, HFBR diffractometer	790 reflections with I > 3σ
Radiation source: reactor	θ_max = 55°, θ_min = 2°
Be (002) monochromator	h = 0→11
θ/2θ scans	k = 0→9
Absorption correction: analytical ?	l = 0→16
T_min = 0.356, T_max = 0.428	2 standard reflections every 100 reflections
1018 measured reflections	intensity decay: none
996 independent reflections

Refinement top

Refinement on F²	0 constraints
Least-squares matrix: full	Ref
R[F² > 2σ(F²)] = 0.068	w = 1/[σ²(F) + 0.0004F²]
wR(F²) = 0.073	(Δ/σ)_max = 0.01
S = 1.04	Δρ_max = 2 % of maximum e Å⁻³
996 reflections	Δρ_min = 2 % of maximum e Å⁻³
83 parameters	Extinction correction: type I, isotropic
0 restraints	Extinction coefficient: 3600 (200)

Crystal data top

(NH₄)₂BeF₄	V = 460.0 (5) Å³
M_r = 121.09	Z = 4
Orthorhombic, Pnma	Neutron radiation, λ = 1.0462 Å
a = 7.531 (3) Å	µ = 0.29 mm⁻¹
b = 5.874 (2) Å	T = 200 K
c = 10.399 (4) Å	4.0 × 3.9 × 3.9 mm

Data collection top

Beamline H6M, HFBR diffractometer	996 independent reflections
Absorption correction: analytical ?	790 reflections with I > 3σ
T_min = 0.356, T_max = 0.428	2 standard reflections every 100 reflections
1018 measured reflections	intensity decay: none

Refinement top

R[F² > 2σ(F²)] = 0.068	0 restraints
wR(F²) = 0.073	Ref
S = 1.04	Δρ_max = 2 % of maximum e Å⁻³
996 reflections	Δρ_min = 2 % of maximum e Å⁻³
83 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
N1	0.1850 (2)	0.2500	0.0990 (1)	?
N2	0.4610 (2)	0.2500	0.8044 (1)	?
Be	0.2505 (2)	0.2500	0.4184 (1)	?
F1	0.0531 (3)	0.2500	0.3817 (3)	?
F2	0.2747 (3)	0.2500	0.5639 (2)	?
F3	0.3354 (2)	0.0348 (3)	0.3638 (2)	?
H1	0.3137 (7)	0.2500	0.1244 (6)	?
H2	0.0996 (9)	0.2500	0.1711 (7)	?
H3	0.1639 (6)	0.1137 (9)	0.0497 (7)	?
H4	0.4897 (10)	0.2500	0.7106 (5)	?
H5	0.5686 (7)	0.2500	0.8596 (7)	?
H6	0.3854 (8)	0.1174 (8)	0.8238 (4)	?

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0158 (4)	0.0186 (4)	0.0231 (5)	0.0000	0.0005 (4)	0.0000
N2	0.0200 (4)	0.0185 (4)	0.0186 (4)	0.0000	0.0014 (4)	0.0000
Be	0.0134 (4)	0.0144 (5)	0.0149 (5)	0.0000	0.0003 (4)	0.0000
F1	0.0156 (8)	0.0447 (12)	0.0524 (16)	0.0000	−0.0087 (9)	0.0000
F2	0.0352 (12)	0.0569 (15)	0.0163 (8)	0.0000	−0.0020 (8)	0.0000
F3	0.0300 (7)	0.0200 (5)	0.0515 (10)	0.0002 (5)	0.0118 (7)	−0.0159 (6)
H1	0.030 (2)	0.066 (3)	0.063 (3)	0.000	−0.014 (2)	0.000
H2	0.054 (3)	0.084 (4)	0.063 (4)	0.000	0.035 (3)	0.000
H3	0.045 (2)	0.074 (3)	0.142 (5)	−0.015 (2)	0.017 (2)	−0.072 (3)
H4	0.077 (4)	0.084 (4)	0.027 (2)	0.000	0.015 (2)	0.000
H5	0.040 (2)	0.081 (4)	0.065 (3)	0.000	−0.021 (2)	0.000
H6	0.106 (4)	0.066 (2)	0.057 (2)	−0.053 (3)	−0.004 (2)	0.001 (2)

Geometric parameters (Å, º) top

N1—H1	1.004 (5)	N2—H6	0.985 (6)
N1—H2	0.988 (7)	Be—F1	1.535 (3)
N1—H3	0.964 (6)	Be—F2	1.524 (3)
N2—H4	1.000 (5)	Be—F3	1.526 (2)
N2—H5	0.993 (6)

H1—N1—H2	115.4 (6)	H5—N2—H6	110.7 (4)
H1—N1—H3	107.4 (3)	F1—Be—F2	111.3 (2)
H2—N1—H3	107.3 (4)	F1—Be—F3	108.2 (1)
H4—N2—H5	112.8 (6)	F2—Be—F3	108.6 (1)
H4—N2—H6	108.9 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···F1ⁱ	1.00 (1)	1.80 (1)	2.779 (2)	163 (1)
N2—H5···F2ⁱⁱ	0.99 (1)	1.74 (1)	2.731 (3)	172 (1)
N2—H6···F3ⁱⁱⁱ	0.99 (1)	1.93 (1)	2.857 (2)	155 (1)

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

(II) ammonium tetrafluoroberyllate top

Crystal data top

(NH₄)₂BeF₄	D_x = 1.750 Mg m⁻³
M_r = 121.09	Neutron radiation, λ = 1.0462 Å
Orthorhombic, Pna2₁	Cell parameters from 32 reflections
Hall symbol: P 2c -2n	θ = 20–27°
a = 15.017 (6) Å	µ = 0.29 mm⁻¹
b = 5.876 (3) Å	T = 163 K
c = 10.418 (4) Å	Box, colorless
V = 919.2 (12) Å³	4.0 × 3.9 × 3.9 mm
Z = 8

Data collection top

Beamline H6M, HFBR diffractometer	1390 reflections with I > 3σ
Radiation source: reactor	θ_max = 55°, θ_min = 2°
Be (002) monochromator	h = 0→23
θ/2θ scans	k = 0→9
Absorption correction: analytical ?	l = 0→16
T_min = 0.346, T_max = 0.432	2 standard reflections every 100 reflections
1972 measured reflections	intensity decay: none
1932 independent reflections

Refinement top

Refinement on F²	0 constraints
Least-squares matrix: full	Ref
R[F² > 2σ(F²)] = 0.048	w = 1/[σ²(F) + 0.0004F²]
wR(F²) = 0.055	(Δ/σ)_max = 0.01
S = 1.07	Δρ_max = 1.5 % of maximum e Å⁻³
1932 reflections	Δρ_min = 1.5 % of maximum e Å⁻³
271 parameters	Extinction correction: type I, isotropic
0 restraints	Extinction coefficient: 3900 (100)

Crystal data top

(NH₄)₂BeF₄	V = 919.2 (12) Å³
M_r = 121.09	Z = 8
Orthorhombic, Pna2₁	Neutron radiation, λ = 1.0462 Å
a = 15.017 (6) Å	µ = 0.29 mm⁻¹
b = 5.876 (3) Å	T = 163 K
c = 10.418 (4) Å	4.0 × 3.9 × 3.9 mm

Data collection top

Beamline H6M, HFBR diffractometer	1932 independent reflections
Absorption correction: analytical ?	1390 reflections with I > 3σ
T_min = 0.346, T_max = 0.432	2 standard reflections every 100 reflections
1972 measured reflections	intensity decay: none

Refinement top

R[F² > 2σ(F²)] = 0.048	0 restraints
wR(F²) = 0.055	Ref
S = 1.07	Δρ_max = 1.5 % of maximum e Å⁻³
1932 reflections	Δρ_min = 1.5 % of maximum e Å⁻³
271 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
N11	0.2188 (2)	0.2600 (3)	0.0990	?
N12	0.4691 (2)	0.2527 (2)	0.3978 (1)	?
N21	0.3534 (2)	0.2562 (2)	0.8015 (3)	?
N22	0.6025 (2)	0.2404 (3)	0.6957 (3)	?
Be1	0.2509 (2)	0.2536 (3)	0.4161 (3)	?
Be2	0.5008 (2)	0.2553 (3)	0.0785 (4)	?
F11	0.1534 (3)	0.2299 (6)	0.3769 (6)	?
F12	0.2584 (3)	0.2867 (6)	0.5617 (4)	?
F13	0.2989 (2)	0.0333 (5)	0.3792 (5)	?
F14	0.2903 (2)	0.4609 (5)	0.3490 (4)	?
F21	0.4026 (3)	0.2750 (7)	0.1231 (6)	?
F22	0.5084 (3)	0.2235 (6)	−0.0674 (4)	?
F23	0.5485 (3)	0.4767 (6)	0.1175 (5)	?
F24	0.5417 (3)	0.0452 (6)	0.1443 (5)	?
H111	0.2820 (6)	0.2840 (15)	0.1285 (10)	?
H112	0.1773 (6)	0.2828 (14)	0.1732 (10)	?
H113	0.2137 (6)	0.0995 (12)	0.0681 (11)	?
H114	0.2050 (4)	0.3645 (10)	0.0218 (6)	?
H121	0.5342 (4)	0.2658 (11)	0.3743 (10)	?
H122	0.4267 (7)	0.2783 (16)	0.3255 (11)	?
H123	0.4604 (4)	0.0883 (9)	0.4239 (7)	?
H124	0.4546 (5)	0.3666 (15)	0.4646 (10)	?
H211	0.3720 (5)	0.2607 (17)	0.7123 (7)	?
H212	0.4091 (6)	0.2233 (15)	0.8513 (10)	?
H213	0.3032 (3)	0.1444 (9)	0.8207 (6)	?
H214	0.3257 (7)	0.4022 (14)	0.8282 (8)	?
H221	0.6125 (7)	0.2383 (12)	0.7935 (8)	?
H222	0.6563 (6)	0.2190 (15)	0.6382 (10)	?
H223	0.5583 (8)	0.1183 (17)	0.6792 (9)	?
H224	0.5849 (5)	0.4021 (10)	0.6796 (8)	?

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N11	0.0129 (9)	0.0124 (8)	0.0146 (8)	−0.0008 (4)	0.0010 (8)	−0.0006 (5)
N12	0.0131 (9)	0.0153 (8)	0.0201 (9)	0.0000 (4)	0.0000 (9)	−0.0005 (5)
N21	0.0115 (8)	0.0161 (9)	0.0148 (9)	−0.0001 (4)	0.0037 (7)	−0.0006 (5)
N22	0.0191 (10)	0.0119 (9)	0.0147 (9)	−0.0025 (4)	0.0018 (8)	0.0002 (5)
Be1	0.0099 (10)	0.0136 (9)	0.0093 (9)	−0.0003 (5)	−0.0020 (7)	−0.0004 (5)
Be2	0.0115 (11)	0.0086 (8)	0.0156 (11)	−0.0001 (5)	−0.0025 (8)	0.0005 (5)
F11	0.0122 (13)	0.0308 (14)	0.038 (2)	0.0010 (11)	−0.0112 (14)	−0.0021 (15)
F12	0.0217 (14)	0.0246 (10)	0.0112 (11)	0.0004 (12)	0.0005 (10)	−0.0014 (11)
F13	0.0181 (11)	0.0116 (9)	0.0265 (14)	0.0004 (9)	0.0060 (10)	−0.0047 (10)
F14	0.0203 (13)	0.0134 (11)	0.0250 (14)	−0.0002 (9)	0.0056 (11)	0.0062 (10)
F21	0.0122 (13)	0.0311 (13)	0.0313 (18)	0.0044 (10)	0.0022 (13)	0.0016 (14)
F22	0.0281 (17)	0.0288 (12)	0.0131 (13)	0.0048 (13)	0.0003 (11)	−0.0035 (13)
F23	0.0233 (13)	0.0126 (10)	0.0269 (15)	−0.0027 (9)	−0.0097 (11)	−0.0012 (10)
F24	0.0200 (13)	0.0152 (11)	0.0315 (18)	0.0013 (9)	−0.0040 (11)	0.0102 (11)
H111	0.040 (4)	0.048 (3)	0.051 (4)	−0.013 (3)	−0.021 (3)	0.012 (3)
H112	0.048 (4)	0.050 (3)	0.040 (4)	−0.009 (3)	0.024 (3)	−0.021 (3)
H113	0.048 (4)	0.031 (2)	0.075 (5)	−0.014 (2)	0.014 (4)	−0.020 (3)
H114	0.034 (3)	0.032 (2)	0.028 (2)	0.005 (2)	−0.008 (2)	0.004 (2)
H121	0.014 (2)	0.045 (3)	0.050 (3)	−0.005 (2)	0.005 (2)	−0.008 (3)
H122	0.044 (4)	0.054 (4)	0.048 (4)	0.001 (3)	−0.025 (4)	0.002 (4)
H123	0.041 (3)	0.023 (2)	0.035 (3)	−0.003 (2)	−0.002 (2)	0.004 (2)
H124	0.036 (3)	0.056 (4)	0.062 (5)	0.002 (3)	0.001 (3)	−0.042 (4)
H211	0.037 (2)	0.107 (6)	0.014 (2)	−0.002 (4)	0.012 (2)	−0.001 (3)
H212	0.026 (3)	0.051 (4)	0.043 (3)	0.006 (3)	−0.004 (2)	0.003 (3)
H213	0.018 (2)	0.031 (2)	0.037 (2)	−0.006 (2)	0.006 (2)	0.005 (2)
H214	0.097 (6)	0.047 (3)	0.033 (3)	0.049 (4)	−0.002 (4)	−0.014 (3)
H221	0.078 (5)	0.040 (3)	0.024 (3)	−0.020 (3)	0.003 (3)	0.006 (2)
H222	0.032 (3)	0.048 (3)	0.042 (4)	0.002 (3)	0.018 (3)	−0.004 (3)
H223	0.079 (5)	0.053 (4)	0.045 (4)	−0.036 (4)	0.006 (4)	0.002 (3)
H224	0.058 (4)	0.024 (2)	0.065 (4)	0.004 (2)	0.008 (3)	−0.010 (2)

Geometric parameters (Å, º) top

Be1—F11	1.526 (6)	N12—H121	1.012 (7)
Be1—F12	1.533 (6)	N12—H122	0.997 (11)
Be1—F13	1.531 (4)	N12—H123	1.012 (6)
Be1—F14	1.524 (4)	N12—H124	0.989 (10)
Be2—F21	1.550 (6)	N21—H211	0.971 (8)
Be2—F22	1.536 (6)	N21—H212	1.003 (10)
Be2—F23	1.540 (5)	N21—H213	1.020 (5)
Be2—F24	1.539 (4)	N21—H214	0.993 (9)
N11—H111	1.008 (9)	N22—H221	1.030 (9)
N11—H112	1.002 (10)	N22—H222	1.012 (10)
N11—H113	0.999 (8)	N22—H223	0.993 (11)
N11—H114	1.033 (6)	N22—H224	1.001 (6)

F11—Be1—F12	110.3 (3)	H121—N12—H122	115.0 (8)
F11—Be1—F13	107.9 (3)	H121—N12—H123	105.2 (5)
F11—Be1—F14	108.8 (3)	H121—N12—H124	109.3 (7)
F12—Be1—F13	108.7 (3)	H122—N12—H123	105.4 (7)
F12—Be1—F14	108.9 (3)	H122—N12—H124	106.8 (8)
F13—Be1—F14	112.2 (3)	H123—N12—H124	115.3 (7)
F21—Be2—F22	112.1 (3)	H211—N21—H212	105.1 (8)
F21—Be2—F23	107.5 (3)	H211—N21—H213	114.7 (7)
F21—Be2—F24	107.8 (3)	H211—N21—H214	111.4 (8)
F22—Be2—F23	108.3 (3)	H212—N21—H213	113.0 (6)
F22—Be2—F24	109.2 (3)	H212—N21—H214	111.8 (8)
F23—Be2—F24	112.0 (3)	H213—N21—H214	101.1 (7)
H111—N11—H112	109.4 (8)	H221—N22—H222	117.9 (9)
H111—N11—H113	107.6 (7)	H221—N22—H223	105.0 (8)
H111—N11—H114	110.1 (7)	H221—N22—H224	102.4 (7)
H112—N11—H113	109.1 (8)	H222—N22—H223	110.0 (8)
H112—N11—H114	113.3 (7)	H222—N22—H224	103.3 (7)
H113—N11—H114	107.1 (7)	H223—N22—H224	118.6 (8)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N11—H111···F21	1.01 (1)	1.81 (1)	2.774 (5)	158 (1)
N11—H113···F12ⁱ	1.00 (1)	1.89 (1)	2.829 (4)	156 (1)
N11—H114···F13ⁱⁱ	1.03 (1)	1.79 (1)	2.810 (5)	170 (1)
N12—H121···F11ⁱⁱⁱ	1.01 (1)	1.79 (1)	2.779 (5)	165 (1)
N12—H123···F22^iv	1.01 (1)	1.89 (1)	2.842 (4)	155 (1)
N12—H124···F23^v	0.99 (1)	1.84 (1)	2.799 (5)	162 (1)
N21—H212···F22^vi	1.00 (1)	1.72 (1)	2.705 (5)	169 (1)
N21—H213···F14^vii	1.02 (1)	1.80 (1)	2.812 (4)	176 (1)
N21—H214···F11^viii	0.99 (1)	2.02 (1)	2.894 (4)	146 (1)
N21—H214···F13^viii	0.99 (1)	2.09 (1)	2.921 (4)	140 (1)
N22—H222···F12ⁱⁱⁱ	1.01 (1)	1.73 (1)	2.730 (5)	169 (1)
N22—H223···F24^iv	0.99 (1)	1.82 (1)	2.792 (4)	166 (1)
N22—H224···F21^v	1.00 (1)	2.00 (1)	2.948 (4)	158 (1)

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

(III) ammonium tetrafluoroberyllate top

Crystal data top

(NH₄)₂BeF₄	D_x = 1.759 Mg m⁻³
M_r = 121.09	Neutron radiation, λ = 1.0462 Å
Orthorhombic, Pna2₁	Cell parameters from 32 reflections
Hall symbol: P 2c -2n	θ = 20–27°
a = 14.997 (5) Å	µ = 0.29 mm⁻¹
b = 5.860 (3) Å	T = 20 K
c = 10.402 (4) Å	Box, colorless
V = 914.1 (11) Å³	4.0 × 3.9 × 3.9 mm
Z = 8

Data collection top

Beamline H6M, HFBR diffractometer	1363 reflections with I > 3σ
Radiation source: reactor	θ_max = 55°, θ_min = 2°
Be (002) monochromator	h = 0→23
θ/2θ scans	k = 0→5
Absorption correction: analytical ?	l = 0→16
T_min = 0.343, T_max = 0.431	2 standard reflections every 100 reflections
1516 measured reflections	intensity decay: none
1484 independent reflections

Refinement top

Refinement on F²	0 constraints
Least-squares matrix: full	Ref
R[F² > 2σ(F²)] = 0.034	w = 1/[σ²(F) + 0.0004F²]
wR(F²) = 0.041	(Δ/σ)_max = 0.01
S = 1.04	Δρ_max = 1 % of maximum e Å⁻³
1484 reflections	Δρ_min = 1 % of maximum e Å⁻³
271 parameters	Extinction correction: type I, isotropic
0 restraints	Extinction coefficient: 5100 (100)

Crystal data top

(NH₄)₂BeF₄	V = 914.1 (11) Å³
M_r = 121.09	Z = 8
Orthorhombic, Pna2₁	Neutron radiation, λ = 1.0462 Å
a = 14.997 (5) Å	µ = 0.29 mm⁻¹
b = 5.860 (3) Å	T = 20 K
c = 10.402 (4) Å	4.0 × 3.9 × 3.9 mm

Data collection top

Beamline H6M, HFBR diffractometer	1484 independent reflections
Absorption correction: analytical ?	1363 reflections with I > 3σ
T_min = 0.343, T_max = 0.431	2 standard reflections every 100 reflections
1516 measured reflections	intensity decay: none

Refinement top

R[F² > 2σ(F²)] = 0.034	0 restraints
wR(F²) = 0.041	Ref
S = 1.04	Δρ_max = 1 % of maximum e Å⁻³
1484 reflections	Δρ_min = 1 % of maximum e Å⁻³
271 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
N11	0.2196 (1)	0.2666 (3)	0.0990	?
N12	0.4712 (1)	0.2538 (2)	0.3941 (1)	?
N21	0.3510 (1)	0.2600 (2)	0.7972 (2)	?
N22	0.6007 (1)	0.2369 (2)	0.6937 (2)	?
Be1	0.2517 (2)	0.2578 (2)	0.4152 (2)	?
Be2	0.5029 (1)	0.2574 (2)	0.0774 (2)	?
F11	0.1544 (2)	0.2247 (4)	0.3718 (3)	?
F12	0.2565 (1)	0.2991 (5)	0.5624 (3)	?
F13	0.3028 (1)	0.0366 (3)	0.3832 (3)	?
F14	0.2905 (1)	0.4680 (4)	0.3475 (3)	?
F21	0.4054 (2)	0.2905 (5)	0.1265 (3)	?
F22	0.5049 (2)	0.2173 (4)	−0.0687 (3)	?
F23	0.5540 (1)	0.4773 (4)	0.1097 (3)	?
F24	0.5421 (1)	0.0466 (4)	0.1451 (3)	?
H111	0.2832 (3)	0.2959 (10)	0.1288 (6)	?
H112	0.1754 (4)	0.2971 (11)	0.1708 (5)	?
H113	0.2151 (3)	0.0991 (10)	0.0735 (5)	?
H114	0.2058 (3)	0.3706 (8)	0.0213 (4)	?
H121	0.5369 (3)	0.2753 (8)	0.3712 (6)	?
H122	0.4319 (3)	0.2792 (9)	0.3164 (5)	?
H123	0.4622 (3)	0.0894 (9)	0.4226 (5)	?
H124	0.4534 (2)	0.3611 (7)	0.4672 (4)	?
H211	0.3634 (5)	0.2620 (7)	0.7056 (5)	?
H212	0.4066 (3)	0.2192 (9)	0.8479 (5)	?
H213	0.2997 (2)	0.1500 (8)	0.8156 (4)	?
H214	0.3332 (3)	0.4222 (8)	0.8244 (4)	?
H221	0.6183 (4)	0.2235 (10)	0.7903 (6)	?
H222	0.6563 (3)	0.1994 (11)	0.6397 (5)	?
H223	0.5494 (2)	0.1289 (7)	0.6742 (4)	?
H224	0.5835 (3)	0.4013 (9)	0.6752 (5)	?

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N11	0.0069 (5)	0.0069 (11)	0.0082 (6)	−0.0002 (3)	−0.0012 (5)	−0.0005 (4)
N12	0.0061 (5)	0.0034 (11)	0.0073 (6)	−0.0005 (3)	−0.0011 (5)	−0.0004 (3)
N21	0.0060 (5)	0.0050 (10)	0.0052 (5)	0.0000 (3)	0.0015 (4)	−0.0001 (3)
N22	0.0076 (6)	0.0050 (11)	0.0094 (6)	−0.0008 (3)	0.0017 (5)	−0.0007 (4)
Be1	0.0070 (6)	0.0012 (12)	0.0070 (7)	0.0005 (3)	0.0002 (5)	0.0003 (3)
Be2	0.0032 (6)	0.0056 (11)	0.0043 (7)	−0.0001 (3)	0.0008 (5)	−0.0002 (3)
F11	0.0044 (6)	0.0072 (12)	0.0081 (7)	0.0000 (6)	−0.0012 (5)	0.0002 (6)
F12	0.0078 (6)	0.0064 (11)	0.0051 (6)	−0.0019 (8)	0.0007 (4)	−0.0015 (7)
F13	0.0056 (5)	0.0019 (10)	0.0074 (6)	0.0003 (5)	0.0005 (5)	0.0002 (6)
F14	0.0069 (6)	0.0045 (11)	0.0080 (6)	−0.0004 (5)	0.0010 (5)	0.0015 (6)
F21	0.0057 (6)	0.0061 (11)	0.0090 (7)	0.0009 (7)	0.0009 (5)	−0.0018 (7)
F22	0.0074 (6)	0.0050 (12)	0.0055 (6)	−0.0009 (7)	0.0005 (4)	−0.0002 (7)
F23	0.0069 (6)	0.0044 (11)	0.0080 (6)	−0.0016 (5)	−0.0013 (5)	−0.0010 (6)
F24	0.0061 (5)	0.0051 (11)	0.0073 (6)	0.0007 (5)	0.0003 (5)	0.0022 (6)
H111	0.017 (2)	0.028 (2)	0.034 (2)	−0.003 (2)	−0.010 (1)	0.003 (2)
H112	0.030 (2)	0.033 (2)	0.025 (2)	0.003 (2)	0.013 (1)	−0.006 (2)
H113	0.032 (2)	0.015 (3)	0.027 (2)	−0.001 (2)	−0.002 (1)	−0.004 (2)
H114	0.028 (2)	0.028 (3)	0.020 (1)	−0.001 (1)	−0.004 (1)	0.009 (1)
H121	0.013 (1)	0.027 (3)	0.029 (2)	−0.005 (1)	0.005 (1)	−0.003 (2)
H122	0.025 (2)	0.025 (3)	0.024 (2)	−0.001 (1)	−0.014 (1)	0.003 (2)
H123	0.031 (2)	0.008 (3)	0.031 (2)	−0.004 (2)	−0.003 (1)	0.008 (2)
H124	0.025 (1)	0.015 (3)	0.023 (1)	0.002 (1)	0.005 (1)	−0.010 (1)
H211	0.047 (3)	0.031 (3)	0.007 (1)	0.001 (2)	0.010 (2)	−0.002 (1)
H212	0.015 (1)	0.024 (3)	0.026 (2)	0.001 (1)	−0.007 (1)	0.003 (2)
H213	0.017 (1)	0.020 (3)	0.029 (1)	−0.006 (1)	0.003 (1)	0.002 (1)
H214	0.033 (2)	0.014 (3)	0.030 (2)	0.008 (2)	−0.001 (1)	−0.006 (1)
H221	0.026 (2)	0.041 (3)	0.020 (2)	−0.003 (2)	−0.002 (2)	0.008 (2)
H222	0.019 (1)	0.029 (2)	0.027 (2)	0.005 (2)	0.010 (1)	−0.005 (2)
H223	0.020 (1)	0.021 (3)	0.025 (1)	−0.010 (1)	0.000 (1)	−0.003 (1)
H224	0.033 (2)	0.010 (3)	0.034 (2)	0.007 (2)	0.003 (1)	0.003 (2)

Geometric parameters (Å, º) top

Be1—F11	1.539 (3)	N12—H121	1.020 (5)
Be1—F12	1.553 (4)	N12—H122	1.012 (6)
Be1—F13	1.542 (3)	N12—H123	1.017 (5)
Be1—F14	1.533 (3)	N12—H124	1.022 (5)
Be2—F21	1.560 (3)	N21—H211	0.971 (6)
Be2—F22	1.539 (4)	N21—H212	1.015 (5)
Be2—F23	1.537 (3)	N21—H213	1.023 (4)
Be2—F24	1.538 (3)	N21—H214	1.027 (5)
N11—H111	1.018 (5)	N22—H221	1.043 (7)
N11—H112	1.014 (6)	N22—H222	1.028 (5)
N11—H113	1.019 (6)	N22—H223	1.017 (4)
N11—H114	1.033 (5)	N22—H224	1.016 (5)

F11—Be1—F12	110.6 (2)	H121—N12—H122	111.0 (4)
F11—Be1—F13	107.6 (2)	H121—N12—H123	108.2 (4)
F11—Be1—F14	109.1 (2)	H121—N12—H124	110.4 (4)
F12—Be1—F13	108.7 (2)	H122—N12—H123	107.2 (4)
F12—Be1—F14	108.1 (2)	H122—N12—H124	110.6 (4)
F13—Be1—F14	112.8 (2)	H123—N12—H124	109.3 (4)
F21—Be2—F22	111.1 (2)	H211—N21—H212	110.8 (6)
F21—Be2—F23	107.0 (2)	H211—N21—H213	109.6 (5)
F21—Be2—F24	108.0 (2)	H211—N21—H214	108.0 (4)
F22—Be2—F23	109.5 (2)	H212—N21—H213	111.9 (4)
F22—Be2—F24	108.8 (2)	H212—N21—H214	106.8 (4)
F23—Be2—F24	112.5 (2)	H213—N21—H214	109.6 (4)
H111—N11—H112	111.0 (5)	H221—N22—H222	107.8 (5)
H111—N11—H113	107.6 (4)	H221—N22—H223	109.7 (4)
H111—N11—H114	109.1 (4)	H221—N22—H224	108.6 (4)
H112—N11—H113	108.6 (5)	H222—N22—H223	111.8 (4)
H112—N11—H114	110.0 (4)	H222—N22—H224	107.8 (5)
H113—N11—H114	110.6 (4)	H223—N22—H224	111.1 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N11—H111···F21	1.02 (1)	1.83 (1)	2.805 (3)	159 (1)
N11—H113···F12ⁱ	1.02 (1)	1.81 (1)	2.789 (4)	159 (1)
N11—H114···F13ⁱⁱ	1.03 (1)	1.74 (1)	2.767 (3)	172 (1)
N12—H121···F11ⁱⁱⁱ	1.02 (1)	1.76 (1)	2.760 (3)	165 (1)
N12—H123···F22^iv	1.02 (1)	1.87 (1)	2.811 (3)	153 (1)
N12—H124···F23^v	1.02 (1)	1.76 (1)	2.767 (3)	167 (1)
N21—H212···F22^vi	1.02 (1)	1.71 (1)	2.708 (3)	167 (1)
N21—H213···F14^vii	1.02 (1)	1.75 (1)	2.777 (3)	178 (1)
N21—H214···F11^viii	1.03 (1)	1.85 (1)	2.833 (3)	159 (1)
N21—H214···F13^viii	1.03 (1)	2.23 (1)	2.958 (2)	126 (1)
N22—H222···F12ⁱⁱⁱ	1.03 (1)	1.70 (1)	2.715 (3)	166 (1)
N22—H223···F24^iv	1.02 (1)	1.74 (1)	2.757 (3)	177 (1)
N22—H224···F21^v	1.02 (1)	1.88 (1)	2.858 (3)	160 (1)

Experimental details

	(I)	(II)	(III)
Crystal data
Chemical formula	(NH₄)₂BeF₄	(NH₄)₂BeF₄	(NH₄)₂BeF₄
M_r	121.09	121.09	121.09
Crystal system, space group	Orthorhombic, Pnma	Orthorhombic, Pna2₁	Orthorhombic, Pna2₁
Temperature (K)	200	163	20
a, b, c (Å)	7.531 (3), 5.874 (2), 10.399 (4)	15.017 (6), 5.876 (3), 10.418 (4)	14.997 (5), 5.860 (3), 10.402 (4)
V (Å³)	460.0 (5)	919.2 (12)	914.1 (11)
Z	4	8	8
Radiation type	Neutron, λ = 1.0462 Å	Neutron, λ = 1.0462 Å	Neutron, λ = 1.0462 Å
µ (mm⁻¹)	0.29	0.29	0.29
Crystal size (mm)	4.0 × 3.9 × 3.9	4.0 × 3.9 × 3.9	4.0 × 3.9 × 3.9

Data collection
Diffractometer	Beamline H6M, HFBR diffractometer	Beamline H6M, HFBR diffractometer	Beamline H6M, HFBR diffractometer
Absorption correction	Analytical	Analytical	Analytical
T_min, T_max	0.356, 0.428	0.346, 0.432	0.343, 0.431
No. of measured, independent and observed (I > 3σ) reflections	1018, 996, 790	1972, 1932, 1390	1516, 1484, 1363
R_int	?	?	?
(sin θ/λ)_max (Å⁻¹)	0.783	0.783	0.783

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.068, 0.073, 1.04	0.048, 0.055, 1.07	0.034, 0.041, 1.04
No. of reflections	996	1932	1484
No. of parameters	83	271	271
H-atom treatment	Ref	Ref	Ref
Δρ_max, Δρ_min (e Å⁻³)	2 % of maximum, 2 % of maximum	1.5 % of maximum, 1.5 % of maximum	1 % of maximum, 1 % of maximum

Computer programs: local, UPALS (Lundgren, 1982).

Hydrogen-bond geometry (Å, º) for (I) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···F1ⁱ	1.004 (5)	1.804 (6)	2.779 (2)	162.7 (6)
N2—H5···F2ⁱⁱ	0.993 (6)	1.744 (6)	2.731 (3)	171.9 (6)
N2—H6···F3ⁱⁱⁱ	0.986 (5)	1.933 (6)	2.857 (2)	155.0 (5)

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

Hydrogen-bond geometry (Å, º) for (II) top

D—H···A	D—H	H···A	D···A	D—H···A
N11—H111···F21	1.008 (9)	1.813 (10)	2.774 (5)	158.0 (9)
N11—H113···F12ⁱ	0.999 (8)	1.887 (8)	2.829 (4)	156.0 (9)
N11—H114···F13ⁱⁱ	1.033 (6)	1.787 (8)	2.810 (5)	169.6 (5)
N12—H121···F11ⁱⁱⁱ	1.011 (7)	1.790 (8)	2.779 (5)	164.7 (9)
N12—H123···F22^iv	1.012 (6)	1.893 (7)	2.842 (4)	154.8 (6)
N12—H124···F23^v	0.989 (10)	1.840 (11)	2.799 (5)	162.3 (8)
N21—H212···F22^vi	1.003 (10)	1.715 (10)	2.705 (5)	168.6 (8)
N21—H213···F14^vii	1.020 (5)	1.795 (6)	2.812 (4)	176.1 (5)
N21—H214···F11^viii	0.993 (9)	2.016 (9)	2.894 (4)	146.2 (9)
N21—H214···F13^viii	0.993 (9)	2.092 (11)	2.921 (4)	139.8 (8)
N22—H222···F12ⁱⁱⁱ	1.012 (10)	1.728 (10)	2.730 (5)	169.1 (9)
N22—H223···F24^iv	0.993 (11)	1.819 (11)	2.792 (4)	165.7 (9)
N22—H224···F21^v	1.001 (6)	1.996 (7)	2.948 (4)	158.0 (7)

Hydrogen-bond geometry (Å, º) for (III) top

D—H···A	D—H	H···A	D···A	D—H···A
N11—H111···F21	1.018 (5)	1.833 (5)	2.805 (3)	158.5 (5)
N11—H113···F12ⁱ	1.019 (8)	1.813 (7)	2.789 (4)	159.3 (4)
N11—H114···F13ⁱⁱ	1.033 (5)	1.740 (5)	2.767 (3)	172.2 (4)
N12—H121···F11ⁱⁱⁱ	1.021 (5)	1.763 (5)	2.760 (3)	164.5 (5)
N12—H123···F22^iv	1.017 (5)	1.866 (6)	2.811 (3)	153.1 (4)
N12—H124···F23^v	1.022 (5)	1.762 (5)	2.767 (3)	166.6 (3)
N21—H212···F22^vi	1.015 (5)	1.711 (5)	2.708 (3)	166.6 (5)
N21—H213···F14^vii	1.023 (4)	1.754 (6)	2.777 (3)	178.4 (4)
N21—H214···F11^viii	1.027 (5)	1.849 (5)	2.833 (3)	159.1 (4)
N21—H214···F13^viii	1.027 (5)	2.232 (5)	2.958 (2)	126.3 (4)
N22—H222···F12ⁱⁱⁱ	1.028 (5)	1.704 (5)	2.715 (3)	166.1 (6)
N22—H223···F24^iv	1.017 (4)	1.742 (4)	2.757 (3)	177.1 (4)
N22—H224···F21^v	1.016 (5)	1.883 (6)	2.858 (3)	159.7 (4)

Bond distances and angles (°, %A) top

	I	II	III
Be1–F11	1.535 (3)	1.526 (6)	1.539 (3)
Be1–F12	1.524 (3)	1.533 (6)	1.553 (4)
Be1–F13	1.526 (2)	1.531 (4)	1.542 (3)
Be1–F14		1.524 (4)	1.533 (3)
Be2–F21		1.550 (6)	1.560 (3)
Be2–F22		1.536 (6)	1.539 (4)
Be2–F23		1.540 (5)	1.537 (3)
Be2–F24		1.539 (4)	1.538 (3)
N11–H111	1.004 (5)	1.008 (9)	1.018 (5)
N11–H112	0.988 (7)	1.002 (10)	1.014 (6)
N11–H113	0.964 (6)	0.999 (8)	1.019 (6)
N11–H114		1.033 (6)	1.033 (5)
N12–H121		1.012 (7)	1.020 (5)
N12–H122		0.997 (11)	1.012 (6)
N12–H123		1.012 (6)	1.017 (5)
N12–H124		0.989 (10)	1.022 (5)
N21–H211	1.000 (5)	0.971 (8)	0.971 (6)
N21–H212	0.993 (6)	1.003 (10)	1.015 (5)
N21–H213	0.985 (6)	1.020 (5)	1.023 (4)
N21–H214		0.993 (9)	1.027 (5)
N22–H221		1.030 (9)	1.043 (7)
N22–H222		1.012 (10)	1.028 (5)
N22–H223		0.993 (11)	1.017 (4)
N22–H224		1.001 (6)	1.016 (5)
	I	II	III
F11–Be1–F12	111.3 (2)	110.3 (3)	110.6 (2)
F11–Be1–F13	108.2 (1)	107.9 (3)	107.6 (2)
F11–Be1–F14	108.6 (1)	108.8 (3)	109.1 (2)
F12–Be1–F13		108.7 (3)	108.7 (2)
F12–Be1–F14		108.9 (3)	108.1 (2)
F13–Be1–F14		112.2 (3)	112.8 (2)
F21–Be2–F22		112.1 (3)	111.1 (2)
F21–Be2–F23		107.5 (3)	107.0 (2)
F21–Be2–F24		107.8 (3)	108.0 (2)
F22–Be2–F23		108.3 (3)	109.5 (2)
F22–Be2–F24		109.2 (3)	108.8 (2)
F23–Be2–F24		112.0 (3)	112.5 (2)
H111–N11–H112	115.4 (6)	109.4 (8)	111.0 (5)
H111–N11–H113	107.4 (3)	107.6 (7)	107.6 (4)
H111–N11–H114	107.3 (4)	110.1 (7)	109.1 (4)
H112–N11–H113		109.1 (8)	108.6 (5)
H112–N11–H114		113.3 (7)	110.0 (4)
H113–N11–H114		107.1 (7)	110.6 (4)
H121–N12–H122		115.0 (8)	111.0 (4)
H121–N12–H123		105.2 (5)	108.2 (4)
H121–N12–H124		109.3 (7)	110.4 (4)
H122–N12–H123		105.4 (7)	107.2 (4)
H122–N12–H124		106.8 (8)	110.6 (4)
H123–N12–H124		115.3 (7)	109.3 (4)
H211–N21–H212	112.8 (6)	105.1 (8)	110.8 (6)
H211–N21–H213	108.9 (4)	114.7 (7)	109.6 (5)
H211–N21–H214	110.7 (4)	111.4 (8)	108.0 (4)
H212–N21–H213		113.0 (6)	111.9 (4)
H212–N21–H214		111.8 (8)	106.8 (4)
H213–N21–H214		101.1 (7)	109.6 (4)
H221–N22–H222		117.9 (9)	107.8 (5)
H221–N22–H223		105.0 (8)	109.7 (4)
H221–N22–H224		102.4 (7)	108.6 (4)
H222–N22–H223		110.0 (8)	111.8 (4)
H222–N22–H224		103.3 (7)	107.8 (5)
H223–N22–H224		118.6 (8)	111.1 (4)

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