Upon heating to 509 K, monoclinic α-K2TaF7 (P21/c) transforms to orthorhombic β-K2TaF7 (Pnma) which is composed of discrete K+ cations and TaF72− anions. In the anion, the Ta atom is sevenfold coordinated by F atoms, with the Ta—F distance varying from 1.88 (2) to 1.965 (19) Å. The two independent K+ cations are surrounded by F atoms positioned within 2.740 (17)–2.979 (10) and 2.989 (17)–3.15 (5) Å. Ta, both K and one of the four F atoms are located on a mirror plane, Wyckoff position 4c.
Supporting information
Key indicators
- Single-crystal X-ray study
- T = 509 K
- Mean (a-F) = 0.027 Å
- R factor = 0.071
- wR factor = 0.220
- Data-to-parameter ratio = 22.7
checkCIF/PLATON results
No syntax errors found
Alert level A
ABSTM02_ALERT_3_A Crystal and compound unsuitable for non-numerical
corrections. Product of mu and tmid > 3.0
Value of mu given = 17.298 tmid = 0.280
| Author Response: The Rint dropped from 0.155 to 0.0617 using
SADABS (Sheldrick, 2001) and the anisotropic atomic displacement
parameters are not unusual. The crystal after measurement
did not diffract and we could not index its faces.
|
PLAT029_ALERT_3_A _diffrn_measured_fraction_theta_full Low ....... 0.87
| Author Response: Unfortunatelly, the crystal suddenly did not diffract anymore.
|
PLAT065_ALERT_3_A Crystal Requires Numerical Correction mu*tmid .. 4.84
| Author Response: As above.
|
PLAT242_ALERT_2_A Check Low Ueq as Compared to Neighbors for Ta
| Author Response: The data was collected at 509K so that the values of displacement
parameters of some atoms are larger than usual.
|
Alert level B
PLAT063_ALERT_3_B Crystal Probably too Large for Beam Size ....... 0.82 mm
Alert level C
PLAT062_ALERT_4_C Rescale T(min) & T(max) by ..................... 0.09
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd. # 2
K
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd. # 3
K
Alert level G
REFLT03_ALERT_1_G ALERT: Expected hkl max differ from CIF values
From the CIF: _diffrn_reflns_theta_max 28.32
From the CIF: _reflns_number_total 771
From the CIF: _diffrn_reflns_limit_ max hkl 5. 5. 16.
From the CIF: _diffrn_reflns_limit_ min hkl -13. -4. -14.
TEST1: Expected hkl limits for theta max
Calculated maximum hkl 13. 7. 16.
Calculated minimum hkl -13. -7. -16.
4 ALERT level A = In general: serious problem
1 ALERT level B = Potentially serious problem
3 ALERT level C = Check and explain
1 ALERT level G = General alerts; check
1 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
3 ALERT type 4 Improvement, methodology, query or suggestion
Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Bruker, 2001); program(s) used to refine structure: SHELXTL; molecular graphics: DIAMOND (Brandenburg, 2000); software used to prepare material for publication: PLATON (Spek, 2003).
Dipotassium heptafluorotantalate(V)
top
Crystal data top
K2TaF7 | F(000) = 696 |
Mr = 392.15 | Dx = 3.798 Mg m−3 |
Orthorhombic, Pnma | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2n | Cell parameters from 801 reflections |
a = 9.8155 (15) Å | θ = 2.7–28.3° |
b = 5.8212 (8) Å | µ = 17.30 mm−1 |
c = 12.0041 (18) Å | T = 509 K |
V = 685.89 (17) Å3 | Rod, colorless |
Z = 4 | 0.82 × 0.28 × 0.28 mm |
Data collection top
Siemens SMART CCD diffractometer | 771 independent reflections |
Radiation source: fine-focus sealed tube | 443 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.062 |
ω scans | θmax = 28.3°, θmin = 2.7° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2002) | h = −13→5 |
Tmin = 0.025, Tmax = 0.085 | k = −4→5 |
2231 measured reflections | l = −14→16 |
Refinement top
Refinement on F2 | 0 restraints |
Least-squares matrix: full | Primary atom site location: structure-invariant direct methods |
R[F2 > 2σ(F2)] = 0.071 | Secondary atom site location: difference Fourier map |
wR(F2) = 0.220 | w = 1/[σ2(Fo2) + (0.123P)2 + 12.4367P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max < 0.001 |
771 reflections | Δρmax = 1.48 e Å−3 |
34 parameters | Δρmin = −2.42 e Å−3 |
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 | Uiso*/Ueq | |
Ta | 0.24967 (14) | 0.2500 | 0.13166 (7) | 0.0307 (5) | |
K1 | 0.1389 (8) | −0.2500 | −0.0586 (6) | 0.049 (2) | |
K2 | 0.4484 (10) | 0.2500 | −0.1716 (8) | 0.071 (3) | |
F1 | 0.344 (2) | 0.032 (4) | 0.0459 (18) | 0.123 (7)* | |
F2 | 0.0992 (18) | 0.028 (3) | 0.1227 (11) | 0.084 (6)* | |
F3 | 0.294 (3) | 0.025 (6) | 0.245 (2) | 0.162 (10)* | |
F4 | 0.185 (5) | 0.2500 | −0.022 (4) | 0.173 (15)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Ta | 0.0494 (7) | 0.0224 (12) | 0.0203 (6) | 0.000 | −0.0049 (6) | 0.000 |
K1 | 0.068 (5) | 0.046 (6) | 0.033 (3) | 0.000 | −0.002 (3) | 0.000 |
K2 | 0.086 (7) | 0.063 (7) | 0.063 (5) | 0.000 | −0.004 (5) | 0.000 |
Geometric parameters (Å, º) top
Ta—F4 | 1.95 (5) | K1—F4 | 2.979 (10) |
Ta—F1 | 1.88 (2) | K1—Taix | 3.856 (5) |
Ta—F1i | 1.88 (2) | K2—F2viii | 2.989 (17) |
Ta—F3i | 1.94 (3) | K2—F2x | 2.989 (17) |
Ta—F3 | 1.94 (3) | K2—F1xi | 3.02 (2) |
Ta—F2 | 1.965 (19) | K2—F1xii | 3.02 (2) |
Ta—F2i | 1.965 (19) | K2—F3xi | 3.12 (3) |
Ta—K1 | 3.856 (5) | K2—F3xii | 3.12 (3) |
Ta—K1ii | 3.856 (5) | K2—F4 | 3.15 (5) |
Ta—K1iii | 3.876 (7) | K2—F3viii | 3.04 (3) |
Ta—K1iv | 3.914 (8) | K2—F3x | 3.04 (3) |
Ta—K2 | 4.130 (9) | K2—F1i | 3.08 (2) |
K1—F2v | 2.740 (17) | K2—F1 | 3.08 (2) |
K1—F2 | 2.740 (17) | F1—K2xii | 3.02 (2) |
K1—F2vi | 2.779 (19) | F2—K1iv | 2.779 (19) |
K1—F2iv | 2.779 (19) | F2—K2iii | 2.989 (17) |
K1—F3vii | 2.78 (3) | F3—K1iii | 2.78 (3) |
K1—F3viii | 2.78 (3) | F3—K2xii | 3.12 (3) |
K1—F1 | 2.88 (2) | F3—K2iii | 3.04 (3) |
K1—F1v | 2.88 (2) | F4—K1ii | 2.979 (10) |
K1—F4ix | 2.979 (10) | | |
| | | |
F4—Ta—F1 | 69.0 (11) | F2v—K1—Taix | 28.8 (4) |
F4—Ta—F1i | 69.0 (11) | F2—K1—Taix | 90.9 (4) |
F1—Ta—F1i | 85.1 (14) | F2vi—K1—Taix | 92.9 (4) |
F4—Ta—F3i | 137.4 (10) | F2iv—K1—Taix | 138.8 (4) |
F1—Ta—F3i | 137.1 (11) | F3vii—K1—Taix | 94.6 (7) |
F1i—Ta—F3i | 79.4 (11) | F3viii—K1—Taix | 142.4 (7) |
F4—Ta—F3 | 137.4 (10) | F1—K1—Taix | 88.6 (5) |
F1—Ta—F3 | 79.4 (11) | F1v—K1—Taix | 27.8 (4) |
F1i—Ta—F3 | 137.1 (11) | F4ix—K1—Taix | 29.7 (9) |
F3i—Ta—F3 | 85.2 (19) | F4—K1—Taix | 127.3 (9) |
F4—Ta—F2 | 72.7 (11) | F2v—K1—Ta | 90.9 (4) |
F1—Ta—F2 | 83.9 (9) | F2—K1—Ta | 28.8 (4) |
F1i—Ta—F2 | 141.6 (8) | F2vi—K1—Ta | 138.8 (4) |
F3i—Ta—F2 | 130.7 (10) | F2iv—K1—Ta | 92.9 (4) |
F3—Ta—F2 | 76.2 (10) | F3vii—K1—Ta | 142.4 (7) |
F4—Ta—F2i | 72.7 (10) | F3viii—K1—Ta | 94.6 (7) |
F1—Ta—F2i | 141.6 (8) | F1—K1—Ta | 27.8 (4) |
F1i—Ta—F2i | 83.9 (9) | F1v—K1—Ta | 88.6 (5) |
F3i—Ta—F2i | 76.2 (10) | F4ix—K1—Ta | 127.3 (9) |
F3—Ta—F2i | 130.7 (10) | F4—K1—Ta | 29.7 (9) |
F2—Ta—F2i | 82.2 (11) | Taix—K1—Ta | 98.03 (16) |
F4—Ta—K1 | 49.33 (16) | F2viii—K2—F2x | 65.6 (7) |
F1—Ta—K1 | 45.8 (7) | F2viii—K2—F1xi | 144.3 (6) |
F1i—Ta—K1 | 108.9 (7) | F2x—K2—F1xi | 102.9 (6) |
F3i—Ta—K1 | 171.7 (10) | F2viii—K2—F1xii | 102.9 (6) |
F3—Ta—K1 | 88.1 (10) | F2x—K2—F1xii | 144.3 (6) |
F2—Ta—K1 | 42.2 (5) | F1xi—K2—F1xii | 65.7 (9) |
F2i—Ta—K1 | 104.6 (5) | F2viii—K2—F3xi | 99.9 (7) |
F4—Ta—K1ii | 49.33 (16) | F2x—K2—F3xi | 67.4 (7) |
F1—Ta—K1ii | 108.9 (7) | F1xi—K2—F3xi | 46.7 (7) |
F1i—Ta—K1ii | 45.8 (7) | F1xii—K2—F3xi | 82.6 (8) |
F3i—Ta—K1ii | 88.1 (10) | F2viii—K2—F3xii | 67.4 (7) |
F3—Ta—K1ii | 171.7 (10) | F2x—K2—F3xii | 99.9 (7) |
F2—Ta—K1ii | 104.6 (5) | F1xi—K2—F3xii | 82.6 (8) |
F2i—Ta—K1ii | 42.2 (5) | F1xii—K2—F3xii | 46.7 (7) |
K1—Ta—K1ii | 98.03 (16) | F3xi—K2—F3xii | 61.7 (12) |
F4—Ta—K1iii | 177.4 (14) | F2viii—K2—F4 | 110.1 (8) |
F1—Ta—K1iii | 112.8 (7) | F2x—K2—F4 | 110.1 (8) |
F1i—Ta—K1iii | 112.8 (7) | F1xi—K2—F4 | 105.6 (8) |
F3i—Ta—K1iii | 42.6 (10) | F1xii—K2—F4 | 105.6 (8) |
F3—Ta—K1iii | 42.6 (10) | F3xi—K2—F4 | 145.7 (7) |
F2—Ta—K1iii | 105.3 (4) | F3xii—K2—F4 | 145.7 (7) |
F2i—Ta—K1iii | 105.3 (4) | F2viii—K2—F3viii | 47.1 (7) |
K1—Ta—K1iii | 130.37 (9) | F2x—K2—F3viii | 83.7 (7) |
K1ii—Ta—K1iii | 130.37 (9) | F1xi—K2—F3viii | 168.5 (8) |
F4—Ta—K1iv | 58.0 (13) | F1xii—K2—F3viii | 114.1 (8) |
F1—Ta—K1iv | 110.8 (6) | F3xi—K2—F3viii | 144.3 (4) |
F1i—Ta—K1iv | 110.8 (6) | F3xii—K2—F3viii | 105.8 (9) |
F3i—Ta—K1iv | 112.1 (8) | F4—K2—F3viii | 63.0 (9) |
F3—Ta—K1iv | 112.1 (8) | F2viii—K2—F3x | 83.7 (7) |
F2—Ta—K1iv | 41.9 (5) | F2x—K2—F3x | 47.1 (7) |
F2i—Ta—K1iv | 41.9 (5) | F1xi—K2—F3x | 114.1 (8) |
K1—Ta—K1iv | 65.95 (14) | F1xii—K2—F3x | 168.5 (8) |
K1ii—Ta—K1iv | 65.95 (14) | F3xi—K2—F3x | 105.8 (9) |
K1iii—Ta—K1iv | 119.34 (15) | F3xii—K2—F3x | 144.3 (4) |
F4—Ta—K2 | 47.2 (14) | F4—K2—F3x | 63.0 (9) |
F1—Ta—K2 | 44.3 (7) | F3viii—K2—F3x | 63.6 (13) |
F1i—Ta—K2 | 44.3 (7) | F2viii—K2—F1i | 150.6 (6) |
F3i—Ta—K2 | 120.8 (9) | F2x—K2—F1i | 115.1 (5) |
F3—Ta—K2 | 120.8 (9) | F1xi—K2—F1i | 65.1 (6) |
F2—Ta—K2 | 107.9 (4) | F1xii—K2—F1i | 91.5 (5) |
F2i—Ta—K2 | 107.9 (4) | F3xi—K2—F1i | 107.3 (7) |
K1—Ta—K2 | 67.11 (13) | F3xii—K2—F1i | 136.1 (7) |
K1ii—Ta—K2 | 67.11 (13) | F4—K2—F1i | 40.7 (8) |
K1iii—Ta—K2 | 135.44 (17) | F3viii—K2—F1i | 103.6 (7) |
K1iv—Ta—K2 | 105.22 (17) | F3x—K2—F1i | 78.6 (7) |
F2v—K1—F2 | 72.4 (8) | F2viii—K2—F1 | 115.1 (5) |
F2v—K1—F2vi | 80.0 (5) | F2x—K2—F1 | 150.6 (6) |
F2—K1—F2vi | 112.0 (4) | F1xi—K2—F1 | 91.5 (5) |
F2v—K1—F2iv | 112.0 (4) | F1xii—K2—F1 | 65.1 (6) |
F2—K1—F2iv | 80.0 (5) | F3xi—K2—F1 | 136.1 (7) |
F2vi—K1—F2iv | 55.4 (8) | F3xii—K2—F1 | 107.3 (7) |
F2v—K1—F3vii | 115.5 (8) | F4—K2—F1 | 40.7 (8) |
F2—K1—F3vii | 170.7 (8) | F3viii—K2—F1 | 78.6 (7) |
F2vi—K1—F3vii | 75.2 (7) | F3x—K2—F1 | 103.6 (7) |
F2iv—K1—F3vii | 100.5 (7) | F1i—K2—F1 | 48.7 (9) |
F2v—K1—F3viii | 170.7 (8) | F2viii—K2—Ta | 130.9 (4) |
F2—K1—F3viii | 115.5 (8) | F2x—K2—Ta | 130.9 (4) |
F2vi—K1—F3viii | 100.5 (7) | F1xi—K2—Ta | 83.0 (4) |
F2iv—K1—F3viii | 75.2 (7) | F1xii—K2—Ta | 83.0 (4) |
F3vii—K1—F3viii | 56.2 (14) | F3xi—K2—Ta | 129.1 (6) |
F2v—K1—F1 | 95.2 (7) | F3xii—K2—Ta | 129.1 (6) |
F2—K1—F1 | 54.4 (6) | F4—K2—Ta | 27.0 (8) |
F2vi—K1—F1 | 166.3 (6) | F3viii—K2—Ta | 85.5 (6) |
F2iv—K1—F1 | 116.2 (5) | F3x—K2—Ta | 85.5 (6) |
F3vii—K1—F1 | 118.2 (8) | F1i—K2—Ta | 25.2 (4) |
F3viii—K1—F1 | 86.3 (8) | F1—K2—Ta | 25.2 (4) |
F2v—K1—F1v | 54.4 (6) | Ta—F1—K1 | 106.4 (8) |
F2—K1—F1v | 95.2 (7) | Ta—F1—K2xii | 115.1 (9) |
F2vi—K1—F1v | 116.2 (5) | K1—F1—K2xii | 112.3 (8) |
F2iv—K1—F1v | 166.3 (6) | Ta—F1—K2 | 110.5 (10) |
F3vii—K1—F1v | 86.3 (8) | K1—F1—K2 | 95.7 (6) |
F3viii—K1—F1v | 118.2 (8) | K2xii—F1—K2 | 114.9 (6) |
F1—K1—F1v | 69.5 (9) | Ta—F2—K1 | 108.9 (7) |
F2v—K1—F4ix | 47.6 (10) | Ta—F2—K1iv | 110.0 (8) |
F2—K1—F4ix | 118.7 (10) | K1—F2—K1iv | 100.0 (5) |
F2vi—K1—F4ix | 73.4 (10) | Ta—F2—K2iii | 115.4 (6) |
F2iv—K1—F4ix | 128.6 (10) | K1—F2—K2iii | 111.0 (6) |
F3vii—K1—F4ix | 68.3 (11) | K1iv—F2—K2iii | 110.4 (6) |
F3viii—K1—F4ix | 123.4 (12) | Ta—F3—K1iii | 109.2 (15) |
F1—K1—F4ix | 112.7 (10) | Ta—F3—K2xii | 109.4 (11) |
F1v—K1—F4ix | 43.3 (10) | K1iii—F3—K2xii | 106.8 (9) |
F2v—K1—F4 | 118.7 (10) | Ta—F3—K2iii | 114.3 (12) |
F2—K1—F4 | 47.6 (10) | K1iii—F3—K2iii | 98.8 (9) |
F2vi—K1—F4 | 128.6 (10) | K2xii—F3—K2iii | 117.2 (12) |
F2iv—K1—F4 | 73.4 (10) | Ta—F4—K1ii | 101.0 (9) |
F3vii—K1—F4 | 123.4 (12) | Ta—F4—K1 | 101.0 (9) |
F3viii—K1—F4 | 68.3 (11) | K1ii—F4—K1 | 155.4 (18) |
F1—K1—F4 | 43.3 (10) | Ta—F4—K2 | 105.9 (18) |
F1v—K1—F4 | 112.7 (10) | K1ii—F4—K2 | 92.3 (9) |
F4ix—K1—F4 | 155.4 (18) | K1—F4—K2 | 92.3 (9) |
Symmetry codes: (i) x, −y+1/2, z; (ii) x, y+1, z; (iii) −x+1/2, −y, z+1/2; (iv) −x, −y, −z; (v) x, −y−1/2, z; (vi) −x, y−1/2, −z; (vii) −x+1/2, y−1/2, z−1/2; (viii) −x+1/2, −y, z−1/2; (ix) x, y−1, z; (x) −x+1/2, y+1/2, z−1/2; (xi) −x+1, y+1/2, −z; (xii) −x+1, −y, −z. |