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An unusual phase transition P4/mncPa\bar 3 has been detected after cooling the (NH4)3TiF7 compound. Some TiF6 octahedra, which are disordered in the room-temperature tetragonal structure, become ordered in the low-temperature cubic phase due to the disappearance of the fourfold axis. Other TiF6 octahedra undergo large rotations resulting in huge displacements of the F atoms by 1.5–1.8 Å that implies a reconstructive phase transition. It was supposed that phases P4/mbm and Pm\bar 3m could be a high-temperature phase and a parent phase, respectively, in (NH4)3TiF7. Therefore, the sequence of phase transitions can be written as Pm\bar 3mP4/mbmP4/mncPa\bar 3. The interrelation between (NH4)3TiF7, (NH4)3GeF7 and (NH4)3PbF7 is found, which allows us to suppose phase transitions in relative compounds.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S2052520614021192/bp5070sup1.cif
Contains datablocks global, I, II

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S2052520614021192/bp5070Isup2.hkl
Contains datablock I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S2052520614021192/bp5070IIsup3.hkl
Contains datablock II

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S2052520614021192/bp5070IIsup4.rtv
Contains datablock II

CCDC references: 1025663; 1025664

Experimental top

Refinement top

Crystal data, data collection and structure refinement details are summarized in Table 1.

Results and discussion top

Computing details top

Data collection: APEX2 (Bruker, 2008) for (I). Cell refinement: APEX2 (Bruker, 2008) for (I). Data reduction: SAINT (Bruker, 2008) for (I). Program(s) used to solve structure: SHELXS97 (Sheldrick, 2008) for (I). Program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) for (I). Molecular graphics: DIAMOND (Brandenburg, 2005) for (I). Software used to prepare material for publication: publCIF (Westrip, 2010) for (I).

Figures top
[Figure 1]
[Figure 2]
[Figure 3]
[Figure 4]
[Figure 5]
[Figure 6]
[Figure 7]
[Figure 8]
(I) Ammonium heptafluorotitanate top
Crystal data top
F6Ti·F·3(H4N)Dx = 1.870 Mg m3
Mr = 235.03Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4/mncCell parameters from 1741 reflections
Hall symbol: -P 4 2nθ = 3.4–25.0°
a = 11.9597 (19) ŵ = 1.10 mm1
c = 11.6747 (19) ÅT = 296 K
V = 1669.9 (5) Å3Bulk, colourless
Z = 80.3 × 0.2 × 0.2 mm
F(000) = 944
Data collection top
Bruker APEX-II CCD
diffractometer
959 independent reflections
Radiation source: fine-focus sealed tube483 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.075
ϕ and ω scansθmax = 26.9°, θmin = 2.4°
Absorption correction: multi-scan
SADABS2004/1. Bruker AXS Inc., Madison, Wisconsin, USA, 2004
h = 1515
Tmin = 0.611, Tmax = 0.746k = 1515
13112 measured reflectionsl = 1414
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.048Only H-atom coordinates refined
wR(F2) = 0.152 w = 1/[σ2(Fo2) + (0.0536P)2 + 3.8962P]
where P = (Fo2 + 2Fc2)/3
S = 1.07(Δ/σ)max = 0.004
959 reflectionsΔρmax = 0.52 e Å3
100 parametersΔρmin = 0.40 e Å3
7 restraintsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0028 (7)
Crystal data top
F6Ti·F·3(H4N)Z = 8
Mr = 235.03Mo Kα radiation
Tetragonal, P4/mncµ = 1.10 mm1
a = 11.9597 (19) ÅT = 296 K
c = 11.6747 (19) Å0.3 × 0.2 × 0.2 mm
V = 1669.9 (5) Å3
Data collection top
Bruker APEX-II CCD
diffractometer
959 independent reflections
Absorption correction: multi-scan
SADABS2004/1. Bruker AXS Inc., Madison, Wisconsin, USA, 2004
483 reflections with I > 2σ(I)
Tmin = 0.611, Tmax = 0.746Rint = 0.075
13112 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0487 restraints
wR(F2) = 0.152Only H-atom coordinates refined
S = 1.07Δρmax = 0.52 e Å3
959 reflectionsΔρmin = 0.40 e Å3
100 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*/UeqOcc. (<1)
Ti10.00000.00000.00000.0272 (6)
Ti20.50000.00000.00000.0286 (5)
Ti30.00000.00000.50000.0289 (6)
N10.2850 (7)0.2606 (6)0.00000.072 (2)
N20.0121 (6)0.2468 (5)0.2206 (5)0.0702 (16)
F10.1326 (3)0.0788 (4)0.00000.0669 (14)
F20.6365 (4)0.0726 (4)0.00000.0755 (15)
F30.00000.00000.1578 (4)0.0620 (18)
F40.4467 (3)0.0950 (3)0.1117 (3)0.0796 (12)
F50.031 (5)0.116 (3)0.407 (3)0.068 (10)0.25
F60.014 (4)0.1430 (17)0.433 (2)0.051 (5)0.25
F70.061 (4)0.095 (5)0.396 (3)0.076 (7)0.25
F80.2399 (3)0.2601 (3)0.25000.0751 (15)
H210.003 (6)0.196 (4)0.264 (4)0.090*
H220.023 (5)0.289 (4)0.259 (5)0.090*
H230.010 (5)0.210 (5)0.168 (4)0.090*
H240.075 (2)0.268 (5)0.226 (6)0.090*
H110.240 (4)0.250 (5)0.049 (4)0.090*
H130.313 (7)0.321 (3)0.00000.090*
H140.324 (6)0.206 (5)0.00000.090*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ti10.0255 (7)0.0255 (7)0.0305 (11)0.0000.0000.000
Ti20.0292 (9)0.0278 (9)0.0289 (8)0.0014 (7)0.0000.000
Ti30.0304 (8)0.0304 (8)0.0259 (11)0.0000.0000.000
N10.040 (4)0.042 (4)0.133 (8)0.008 (3)0.0000.000
N20.108 (5)0.052 (3)0.051 (3)0.001 (3)0.001 (4)0.008 (2)
F10.048 (3)0.063 (3)0.090 (3)0.025 (2)0.0000.000
F20.050 (3)0.090 (4)0.086 (3)0.031 (2)0.0000.000
F30.076 (3)0.076 (3)0.033 (3)0.0000.0000.000
F40.094 (3)0.075 (2)0.069 (2)0.0024 (19)0.0164 (19)0.032 (2)
F50.08 (3)0.06 (2)0.060 (17)0.001 (16)0.018 (15)0.038 (16)
F60.049 (15)0.021 (7)0.083 (13)0.002 (11)0.001 (12)0.015 (7)
F70.069 (18)0.09 (2)0.069 (14)0.039 (13)0.022 (13)0.052 (14)
F80.076 (2)0.076 (2)0.074 (3)0.006 (2)0.0041 (18)0.0041 (18)
Geometric parameters (Å, º) top
Ti1—F3i1.842 (5)Ti3—F5ix1.80 (2)
Ti1—F31.842 (5)Ti3—F5x1.80 (2)
Ti1—F1i1.845 (4)Ti3—F5xi1.80 (2)
Ti1—F1ii1.845 (4)Ti3—F5xii1.80 (2)
Ti1—F1iii1.845 (4)Ti3—F7viii1.819 (16)
Ti1—F11.845 (4)Ti3—F7ix1.819 (16)
Ti2—F4iv1.843 (3)Ti3—F7vii1.819 (16)
Ti2—F4v1.843 (3)Ti3—F7iii1.819 (16)
Ti2—F4vi1.843 (3)F5—F60.70 (5)
Ti2—F41.843 (3)F5—F7iii1.02 (2)
Ti2—F2iv1.850 (4)F5—F71.13 (4)
Ti2—F21.850 (4)F6—F70.91 (8)
Ti3—F51.80 (2)F6—F6viii1.57 (6)
Ti3—F5vii1.80 (2)F6—F7iii1.69 (4)
Ti3—F5iii1.80 (2)F7—F5xi1.02 (2)
Ti3—F5viii1.80 (2)F7—F6xi1.69 (4)
F3i—Ti1—F3180.0F5iii—Ti3—F7viii147.2 (8)
F3i—Ti1—F1i90.0F5viii—Ti3—F7viii36.4 (12)
F3—Ti1—F1i90.0F5ix—Ti3—F7viii143.6 (12)
F3i—Ti1—F1ii90.0F5x—Ti3—F7viii91.7 (11)
F3—Ti1—F1ii90.0F5xi—Ti3—F7viii88.3 (11)
F1i—Ti1—F1ii90.0F5xii—Ti3—F7viii89.7 (10)
F3i—Ti1—F1iii90.0F5—Ti3—F7ix89.7 (10)
F3—Ti1—F1iii90.0F5vii—Ti3—F7ix147.2 (8)
F1i—Ti1—F1iii90.0F5iii—Ti3—F7ix32.8 (8)
F1ii—Ti1—F1iii180.0 (2)F5viii—Ti3—F7ix143.6 (12)
F3i—Ti1—F190.0F5ix—Ti3—F7ix36.4 (12)
F3—Ti1—F190.0F5x—Ti3—F7ix88.3 (11)
F1i—Ti1—F1180.0F5xi—Ti3—F7ix91.7 (11)
F1ii—Ti1—F190.0F5xii—Ti3—F7ix90.3 (10)
F1iii—Ti1—F190.0F7viii—Ti3—F7ix180.000 (2)
F4iv—Ti2—F4v90.0 (2)F5—Ti3—F7vii147.2 (8)
F4iv—Ti2—F4vi90.0 (2)F5vii—Ti3—F7vii36.4 (12)
F4v—Ti2—F4vi180.0 (3)F5iii—Ti3—F7vii143.6 (12)
F4iv—Ti2—F4180.0F5viii—Ti3—F7vii91.7 (11)
F4v—Ti2—F490.0 (2)F5ix—Ti3—F7vii88.3 (11)
F4vi—Ti2—F490.0 (2)F5x—Ti3—F7vii89.7 (10)
F4iv—Ti2—F2iv90.91 (15)F5xi—Ti3—F7vii90.3 (10)
F4v—Ti2—F2iv89.09 (15)F5xii—Ti3—F7vii32.8 (8)
F4vi—Ti2—F2iv90.91 (15)F7viii—Ti3—F7vii63.3 (16)
F4—Ti2—F2iv89.10 (15)F7ix—Ti3—F7vii116.7 (16)
F4iv—Ti2—F289.09 (15)F5—Ti3—F7iii32.8 (8)
F4v—Ti2—F290.91 (15)F5vii—Ti3—F7iii143.6 (12)
F4vi—Ti2—F289.09 (15)F5iii—Ti3—F7iii36.4 (12)
F4—Ti2—F290.90 (15)F5viii—Ti3—F7iii88.3 (11)
F2iv—Ti2—F2180.0F5ix—Ti3—F7iii91.7 (11)
F5—Ti3—F5vii111.5 (14)F5x—Ti3—F7iii90.3 (10)
F5—Ti3—F5iii68.5 (14)F5xi—Ti3—F7iii89.7 (10)
F5vii—Ti3—F5iii180.000 (3)F5xii—Ti3—F7iii147.2 (8)
F5—Ti3—F5viii74 (3)F7viii—Ti3—F7iii116.7 (16)
F5vii—Ti3—F5viii68.5 (14)F7ix—Ti3—F7iii63.3 (16)
F5iii—Ti3—F5viii111.5 (14)F7vii—Ti3—F7iii180.0 (18)
F5—Ti3—F5ix106 (3)F6—F5—F7iii159 (6)
F5vii—Ti3—F5ix111.5 (14)F6—F5—F754 (6)
F5iii—Ti3—F5ix68.5 (14)F7iii—F5—F7125 (6)
F5viii—Ti3—F5ix180.000 (3)F6—F5—Ti386 (4)
F5—Ti3—F5x111.5 (14)F7iii—F5—Ti374.4 (17)
F5vii—Ti3—F5x106 (3)F7—F5—Ti372.5 (15)
F5iii—Ti3—F5x74 (3)F5—F6—F789 (5)
F5viii—Ti3—F5x68.5 (14)F5—F6—F6viii116 (4)
F5ix—Ti3—F5x111.5 (14)F7—F6—F6viii118 (2)
F5—Ti3—F5xi68.5 (14)F7—F6—F7iii89 (3)
F5vii—Ti3—F5xi74 (3)F6viii—F6—F7iii105 (2)
F5iii—Ti3—F5xi106 (3)F5—F6—Ti372 (3)
F5viii—Ti3—F5xi111.5 (14)F7—F6—Ti371.4 (19)
F5ix—Ti3—F5xi68.5 (14)F6viii—F6—Ti365.4 (8)
F5x—Ti3—F5xi180.000 (2)F7iii—F6—Ti360.7 (11)
F5—Ti3—F5xii180.000 (5)F6—F7—F5xi144 (5)
F5vii—Ti3—F5xii68.5 (14)F5xi—F7—F5141 (3)
F5iii—Ti3—F5xii111.5 (14)F6—F7—F6xi136 (4)
F5viii—Ti3—F5xii106 (3)F5—F7—F6xi135.0 (18)
F5ix—Ti3—F5xii74 (3)F6—F7—Ti380 (2)
F5x—Ti3—F5xii68.5 (14)F5xi—F7—Ti372.8 (16)
F5xi—Ti3—F5xii111.5 (14)F5—F7—Ti371.1 (16)
F5—Ti3—F7viii90.3 (10)F6xi—F7—Ti365.1 (13)
F5vii—Ti3—F7viii32.8 (8)
Symmetry codes: (i) x, y, z; (ii) y, x, z; (iii) y, x, z; (iv) x+1, y, z; (v) x, y, z; (vi) x+1, y, z; (vii) y, x, z+1; (viii) x, y, z+1; (ix) x, y, z; (x) y, x, z+1; (xi) y, x, z; (xii) x, y, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H11···F10.80 (5)2.48 (6)2.837 (9)108 (5)
N1—H11···F80.80 (5)2.35 (5)2.968 (2)135 (4)
N1—H11···F2xiii0.80 (5)2.49 (5)2.823 (9)107 (4)
N1—H11···F2xiv0.80 (5)2.49 (5)2.823 (9)107 (4)
N1—H14···F40.80 (5)2.37 (6)3.060 (8)145 (2)
N1—H14···F4v0.80 (5)2.37 (6)3.060 (8)145 (2)
N2—H22···F4xv0.80 (6)2.08 (5)2.833 (7)158 (6)
N2—H23···F1iii0.80 (5)2.32 (5)3.111 (6)170 (6)
N2—H24···F80.80 (3)1.99 (3)2.751 (8)159 (6)
Symmetry codes: (iii) y, x, z; (v) x, y, z; (xiii) y, x+1, z; (xiv) y, x+1, z; (xv) x1/2, y+1/2, z+1/2.
(II) top
Crystal data top
F6Ti·F·3(H4N)Z = 8
Mr = 235.00Dx = 1.908 Mg m3
Cubic, Pa3Cu Kα12 radiation, λ = 1.5406, 1.5443 Å
Hall symbol: -P 2ac 2ab 3T = 143 K
a = 11.78316 (15) Åcolourless
V = 1636.01 (6) Å3?, ? × ? × ? mm
Data collection top
D8 ADVANCE Bruker
diffractometer
Data collection mode: reflection
None monochromatorScan method: step
Specimen mounting: flat, densely packed2θmin = 11.013°, 2θmax = 139.987°, 2θstep = 0.016°
Refinement top
Rp = 3.926Profile function: PearsonVII
Rwp = 4.85061 parameters
Rexp = 2.2139 restraints
RBragg = 1.79(Δ/σ)max = 0.010
χ2 = 4.800Preferred orientation correction: no preferred orientation
8060.88125 data points
Crystal data top
F6Ti·F·3(H4N)Z = 8
Mr = 235.00Cu Kα12 radiation, λ = 1.5406, 1.5443 Å
Cubic, Pa3T = 143 K
a = 11.78316 (15) Å?, ? × ? × ? mm
V = 1636.01 (6) Å3
Data collection top
D8 ADVANCE Bruker
diffractometer
Scan method: step
Specimen mounting: flat, densely packed2θmin = 11.013°, 2θmax = 139.987°, 2θstep = 0.016°
Data collection mode: reflection
Refinement top
Rp = 3.926χ2 = 4.800
Rwp = 4.8508060.88125 data points
Rexp = 2.21361 parameters
RBragg = 1.799 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/Beq
Ti10000
Ti20.5000
F10.15394 (17)0.0155 (2)0.0142 (3)0
F20.3899 (2)0.0958 (3)0.05309 (17)0
F30.2569 (3)0.2569 (3)0.2569 (3)0
N0.2406 (4)0.2352 (3)0.4821 (3)0
H10.2631450.1645400.5003864*
H20.2363750.2417010.4061184*
H30.1719170.2487030.5126714*
H40.2909510.2858050.5092374*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ti10.0210 (17)0.0210 (17)0.0210 (17)0.0010 (11)0.0010 (11)0.0010 (11)
Ti20.0143 (17)0.0143 (17)0.0143 (17)0.0042 (10)0.0042 (10)0.0042 (10)
F10.035 (2)0.034 (4)0.053 (4)0.0183 (19)0.009 (2)0.0085 (19)
F20.031 (3)0.013 (3)0.027 (2)0.0031 (14)0.0034 (18)0.0033 (18)
F30.0390 (18)0.0390 (18)0.0390 (18)0.012 (3)0.012 (3)0.012 (3)
N0.028 (9)0.029 (10)0.054 (4)0.006 (3)0.020 (4)0.010 (4)
Bond lengths (Å) top
Ti1—F11.831 (3)N—H20.9000
Ti2—F21.830 (3)N—H30.9000
N—H10.9000N—H40.9000

Experimental details

(I)(II)
Crystal data
Chemical formulaF6Ti·F·3(H4N)F6Ti·F·3(H4N)
Mr235.03235.00
Crystal system, space groupTetragonal, P4/mncCubic, Pa3
Temperature (K)296143
a, b, c (Å)11.9597 (19), 11.9597 (19), 11.6747 (19)11.78316 (15), 11.78316 (15), 11.78316 (15)
α, β, γ (°)90, 90, 9090, 90, 90
V3)1669.9 (5)1636.01 (6)
Z88
Radiation typeMo KαCu Kα12, λ = 1.5406, 1.5443 Å
µ (mm1)1.10
Specimen shape, size (mm)0.3 × 0.2 × 0.2?, ? × ? × ?
Data collection
DiffractometerBruker APEX-II CCD
diffractometer
D8 ADVANCE Bruker
diffractometer
Specimen mountingFlat, densely packed
Data collection modeReflection
Data collection methodϕ and ω scansStep
Absorption correctionMulti-scan
SADABS2004/1. Bruker AXS Inc., Madison, Wisconsin, USA, 2004
Tmin, Tmax0.611, 0.746
No. of measured, independent and
observed [I > 2σ(I)] reflections
13112, 959, 483
Rint0.075
θ values (°)θmax = 26.9, θmin = 2.42θmin = 11.013 2θmax = 139.987 2θstep = 0.016
(sin θ/λ)max1)0.637
Refinement
R factors and goodness of fitR[F2 > 2σ(F2)] = 0.048, wR(F2) = 0.152, S = 1.07Rp = 3.926, Rwp = 4.850, Rexp = 2.213, RBragg = 1.79, χ2 = 4.800
No. of reflections/data points9598060.88125
No. of parameters10061
No. of restraints79
H-atom treatmentOnly H-atom coordinates refined?
Δρmax, Δρmin (e Å3)0.52, 0.40

Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2005), publCIF (Westrip, 2010).

Hydrogen-bond geometry (Å, º) for (I) top
D—H···AD—HH···AD···AD—H···A
N1—H11···F10.80 (5)2.48 (6)2.837 (9)108 (5)
N1—H11···F80.80 (5)2.35 (5)2.968 (2)135 (4)
N1—H11···F2i0.80 (5)2.49 (5)2.823 (9)107 (4)
N1—H11···F2ii0.80 (5)2.49 (5)2.823 (9)107 (4)
N1—H14···F40.80 (5)2.37 (6)3.060 (8)145 (2)
N1—H14···F4iii0.80 (5)2.37 (6)3.060 (8)145 (2)
N2—H22···F4iv0.80 (6)2.08 (5)2.833 (7)158 (6)
N2—H23···F1v0.80 (5)2.32 (5)3.111 (6)170 (6)
N2—H24···F80.80 (3)1.99 (3)2.751 (8)159 (6)
Symmetry codes: (i) y, x+1, z; (ii) y, x+1, z; (iii) x, y, z; (iv) x1/2, y+1/2, z+1/2; (v) y, x, z.
 

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