Download citation
Download citation
link to html
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

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536806009147/wm2004sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536806009147/wm2004Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 509 K
  • Mean [sigma](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

Computing details top

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
K2TaF7F(000) = 696
Mr = 392.15Dx = 3.798 Mg m3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 801 reflections
a = 9.8155 (15) Åθ = 2.7–28.3°
b = 5.8212 (8) ŵ = 17.30 mm1
c = 12.0041 (18) ÅT = 509 K
V = 685.89 (17) Å3Rod, colorless
Z = 40.82 × 0.28 × 0.28 mm
Data collection top
Siemens SMART CCD
diffractometer
771 independent reflections
Radiation source: fine-focus sealed tube443 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.062
ω scansθmax = 28.3°, θmin = 2.7°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2002)
h = 135
Tmin = 0.025, Tmax = 0.085k = 45
2231 measured reflectionsl = 1416
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.071Secondary 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 reflectionsΔρmax = 1.48 e Å3
34 parametersΔρmin = 2.42 e Å3
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*/Ueq
Ta0.24967 (14)0.25000.13166 (7)0.0307 (5)
K10.1389 (8)0.25000.0586 (6)0.049 (2)
K20.4484 (10)0.25000.1716 (8)0.071 (3)
F10.344 (2)0.032 (4)0.0459 (18)0.123 (7)*
F20.0992 (18)0.028 (3)0.1227 (11)0.084 (6)*
F30.294 (3)0.025 (6)0.245 (2)0.162 (10)*
F40.185 (5)0.25000.022 (4)0.173 (15)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ta0.0494 (7)0.0224 (12)0.0203 (6)0.0000.0049 (6)0.000
K10.068 (5)0.046 (6)0.033 (3)0.0000.002 (3)0.000
K20.086 (7)0.063 (7)0.063 (5)0.0000.004 (5)0.000
Geometric parameters (Å, º) top
Ta—F41.95 (5)K1—F42.979 (10)
Ta—F11.88 (2)K1—Taix3.856 (5)
Ta—F1i1.88 (2)K2—F2viii2.989 (17)
Ta—F3i1.94 (3)K2—F2x2.989 (17)
Ta—F31.94 (3)K2—F1xi3.02 (2)
Ta—F21.965 (19)K2—F1xii3.02 (2)
Ta—F2i1.965 (19)K2—F3xi3.12 (3)
Ta—K13.856 (5)K2—F3xii3.12 (3)
Ta—K1ii3.856 (5)K2—F43.15 (5)
Ta—K1iii3.876 (7)K2—F3viii3.04 (3)
Ta—K1iv3.914 (8)K2—F3x3.04 (3)
Ta—K24.130 (9)K2—F1i3.08 (2)
K1—F2v2.740 (17)K2—F13.08 (2)
K1—F22.740 (17)F1—K2xii3.02 (2)
K1—F2vi2.779 (19)F2—K1iv2.779 (19)
K1—F2iv2.779 (19)F2—K2iii2.989 (17)
K1—F3vii2.78 (3)F3—K1iii2.78 (3)
K1—F3viii2.78 (3)F3—K2xii3.12 (3)
K1—F12.88 (2)F3—K2iii3.04 (3)
K1—F1v2.88 (2)F4—K1ii2.979 (10)
K1—F4ix2.979 (10)
F4—Ta—F169.0 (11)F2v—K1—Taix28.8 (4)
F4—Ta—F1i69.0 (11)F2—K1—Taix90.9 (4)
F1—Ta—F1i85.1 (14)F2vi—K1—Taix92.9 (4)
F4—Ta—F3i137.4 (10)F2iv—K1—Taix138.8 (4)
F1—Ta—F3i137.1 (11)F3vii—K1—Taix94.6 (7)
F1i—Ta—F3i79.4 (11)F3viii—K1—Taix142.4 (7)
F4—Ta—F3137.4 (10)F1—K1—Taix88.6 (5)
F1—Ta—F379.4 (11)F1v—K1—Taix27.8 (4)
F1i—Ta—F3137.1 (11)F4ix—K1—Taix29.7 (9)
F3i—Ta—F385.2 (19)F4—K1—Taix127.3 (9)
F4—Ta—F272.7 (11)F2v—K1—Ta90.9 (4)
F1—Ta—F283.9 (9)F2—K1—Ta28.8 (4)
F1i—Ta—F2141.6 (8)F2vi—K1—Ta138.8 (4)
F3i—Ta—F2130.7 (10)F2iv—K1—Ta92.9 (4)
F3—Ta—F276.2 (10)F3vii—K1—Ta142.4 (7)
F4—Ta—F2i72.7 (10)F3viii—K1—Ta94.6 (7)
F1—Ta—F2i141.6 (8)F1—K1—Ta27.8 (4)
F1i—Ta—F2i83.9 (9)F1v—K1—Ta88.6 (5)
F3i—Ta—F2i76.2 (10)F4ix—K1—Ta127.3 (9)
F3—Ta—F2i130.7 (10)F4—K1—Ta29.7 (9)
F2—Ta—F2i82.2 (11)Taix—K1—Ta98.03 (16)
F4—Ta—K149.33 (16)F2viii—K2—F2x65.6 (7)
F1—Ta—K145.8 (7)F2viii—K2—F1xi144.3 (6)
F1i—Ta—K1108.9 (7)F2x—K2—F1xi102.9 (6)
F3i—Ta—K1171.7 (10)F2viii—K2—F1xii102.9 (6)
F3—Ta—K188.1 (10)F2x—K2—F1xii144.3 (6)
F2—Ta—K142.2 (5)F1xi—K2—F1xii65.7 (9)
F2i—Ta—K1104.6 (5)F2viii—K2—F3xi99.9 (7)
F4—Ta—K1ii49.33 (16)F2x—K2—F3xi67.4 (7)
F1—Ta—K1ii108.9 (7)F1xi—K2—F3xi46.7 (7)
F1i—Ta—K1ii45.8 (7)F1xii—K2—F3xi82.6 (8)
F3i—Ta—K1ii88.1 (10)F2viii—K2—F3xii67.4 (7)
F3—Ta—K1ii171.7 (10)F2x—K2—F3xii99.9 (7)
F2—Ta—K1ii104.6 (5)F1xi—K2—F3xii82.6 (8)
F2i—Ta—K1ii42.2 (5)F1xii—K2—F3xii46.7 (7)
K1—Ta—K1ii98.03 (16)F3xi—K2—F3xii61.7 (12)
F4—Ta—K1iii177.4 (14)F2viii—K2—F4110.1 (8)
F1—Ta—K1iii112.8 (7)F2x—K2—F4110.1 (8)
F1i—Ta—K1iii112.8 (7)F1xi—K2—F4105.6 (8)
F3i—Ta—K1iii42.6 (10)F1xii—K2—F4105.6 (8)
F3—Ta—K1iii42.6 (10)F3xi—K2—F4145.7 (7)
F2—Ta—K1iii105.3 (4)F3xii—K2—F4145.7 (7)
F2i—Ta—K1iii105.3 (4)F2viii—K2—F3viii47.1 (7)
K1—Ta—K1iii130.37 (9)F2x—K2—F3viii83.7 (7)
K1ii—Ta—K1iii130.37 (9)F1xi—K2—F3viii168.5 (8)
F4—Ta—K1iv58.0 (13)F1xii—K2—F3viii114.1 (8)
F1—Ta—K1iv110.8 (6)F3xi—K2—F3viii144.3 (4)
F1i—Ta—K1iv110.8 (6)F3xii—K2—F3viii105.8 (9)
F3i—Ta—K1iv112.1 (8)F4—K2—F3viii63.0 (9)
F3—Ta—K1iv112.1 (8)F2viii—K2—F3x83.7 (7)
F2—Ta—K1iv41.9 (5)F2x—K2—F3x47.1 (7)
F2i—Ta—K1iv41.9 (5)F1xi—K2—F3x114.1 (8)
K1—Ta—K1iv65.95 (14)F1xii—K2—F3x168.5 (8)
K1ii—Ta—K1iv65.95 (14)F3xi—K2—F3x105.8 (9)
K1iii—Ta—K1iv119.34 (15)F3xii—K2—F3x144.3 (4)
F4—Ta—K247.2 (14)F4—K2—F3x63.0 (9)
F1—Ta—K244.3 (7)F3viii—K2—F3x63.6 (13)
F1i—Ta—K244.3 (7)F2viii—K2—F1i150.6 (6)
F3i—Ta—K2120.8 (9)F2x—K2—F1i115.1 (5)
F3—Ta—K2120.8 (9)F1xi—K2—F1i65.1 (6)
F2—Ta—K2107.9 (4)F1xii—K2—F1i91.5 (5)
F2i—Ta—K2107.9 (4)F3xi—K2—F1i107.3 (7)
K1—Ta—K267.11 (13)F3xii—K2—F1i136.1 (7)
K1ii—Ta—K267.11 (13)F4—K2—F1i40.7 (8)
K1iii—Ta—K2135.44 (17)F3viii—K2—F1i103.6 (7)
K1iv—Ta—K2105.22 (17)F3x—K2—F1i78.6 (7)
F2v—K1—F272.4 (8)F2viii—K2—F1115.1 (5)
F2v—K1—F2vi80.0 (5)F2x—K2—F1150.6 (6)
F2—K1—F2vi112.0 (4)F1xi—K2—F191.5 (5)
F2v—K1—F2iv112.0 (4)F1xii—K2—F165.1 (6)
F2—K1—F2iv80.0 (5)F3xi—K2—F1136.1 (7)
F2vi—K1—F2iv55.4 (8)F3xii—K2—F1107.3 (7)
F2v—K1—F3vii115.5 (8)F4—K2—F140.7 (8)
F2—K1—F3vii170.7 (8)F3viii—K2—F178.6 (7)
F2vi—K1—F3vii75.2 (7)F3x—K2—F1103.6 (7)
F2iv—K1—F3vii100.5 (7)F1i—K2—F148.7 (9)
F2v—K1—F3viii170.7 (8)F2viii—K2—Ta130.9 (4)
F2—K1—F3viii115.5 (8)F2x—K2—Ta130.9 (4)
F2vi—K1—F3viii100.5 (7)F1xi—K2—Ta83.0 (4)
F2iv—K1—F3viii75.2 (7)F1xii—K2—Ta83.0 (4)
F3vii—K1—F3viii56.2 (14)F3xi—K2—Ta129.1 (6)
F2v—K1—F195.2 (7)F3xii—K2—Ta129.1 (6)
F2—K1—F154.4 (6)F4—K2—Ta27.0 (8)
F2vi—K1—F1166.3 (6)F3viii—K2—Ta85.5 (6)
F2iv—K1—F1116.2 (5)F3x—K2—Ta85.5 (6)
F3vii—K1—F1118.2 (8)F1i—K2—Ta25.2 (4)
F3viii—K1—F186.3 (8)F1—K2—Ta25.2 (4)
F2v—K1—F1v54.4 (6)Ta—F1—K1106.4 (8)
F2—K1—F1v95.2 (7)Ta—F1—K2xii115.1 (9)
F2vi—K1—F1v116.2 (5)K1—F1—K2xii112.3 (8)
F2iv—K1—F1v166.3 (6)Ta—F1—K2110.5 (10)
F3vii—K1—F1v86.3 (8)K1—F1—K295.7 (6)
F3viii—K1—F1v118.2 (8)K2xii—F1—K2114.9 (6)
F1—K1—F1v69.5 (9)Ta—F2—K1108.9 (7)
F2v—K1—F4ix47.6 (10)Ta—F2—K1iv110.0 (8)
F2—K1—F4ix118.7 (10)K1—F2—K1iv100.0 (5)
F2vi—K1—F4ix73.4 (10)Ta—F2—K2iii115.4 (6)
F2iv—K1—F4ix128.6 (10)K1—F2—K2iii111.0 (6)
F3vii—K1—F4ix68.3 (11)K1iv—F2—K2iii110.4 (6)
F3viii—K1—F4ix123.4 (12)Ta—F3—K1iii109.2 (15)
F1—K1—F4ix112.7 (10)Ta—F3—K2xii109.4 (11)
F1v—K1—F4ix43.3 (10)K1iii—F3—K2xii106.8 (9)
F2v—K1—F4118.7 (10)Ta—F3—K2iii114.3 (12)
F2—K1—F447.6 (10)K1iii—F3—K2iii98.8 (9)
F2vi—K1—F4128.6 (10)K2xii—F3—K2iii117.2 (12)
F2iv—K1—F473.4 (10)Ta—F4—K1ii101.0 (9)
F3vii—K1—F4123.4 (12)Ta—F4—K1101.0 (9)
F3viii—K1—F468.3 (11)K1ii—F4—K1155.4 (18)
F1—K1—F443.3 (10)Ta—F4—K2105.9 (18)
F1v—K1—F4112.7 (10)K1ii—F4—K292.3 (9)
F4ix—K1—F4155.4 (18)K1—F4—K292.3 (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, y1/2, z; (vi) x, y1/2, z; (vii) x+1/2, y1/2, z1/2; (viii) x+1/2, y, z1/2; (ix) x, y1, z; (x) x+1/2, y+1/2, z1/2; (xi) x+1, y+1/2, z; (xii) x+1, y, z.
 

Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds