Fluxional seven-coordinated fluorido- and oxofluoridotantalates

Seven-coordinated (NH₄)₂TaF₇, Rb₂TaF₇ and Rb₃TaOF₆ were synthesized in single-crystal form and their structures were determined. A monocapped trigonal prism (CTP) or a pentagonal bipyramid (PB) of the TaF₇²⁻ anion are stereochemically nonrigid and coexist in the first two compounds as a result of strong intraspheric dynamics. Upon cooling, tetragonal Rb₂TaF₇ undergoes a first-order phase transition at 145 K and the seven-coordinated polyhedron transforms into a regular CTP. The seven-coordinated polyhedron in (NH₄)₂TaF₇ approaches the PB configuration as the temperature decreases. Cubic elpasolite-like Rb₃TaOF₆ is characterized by the simultaneous two-state coexistence of TaOF₆³⁻ of the PB shape as rigidly reoriented and as fluxional. In the former case, the central atom is disordered over the octahedron in the unit cell, allowing the determination of the short Ta—O distance, whereas in the latter case, tantalum remains in the polyhedron center, resulting in synchronous Ta—O and Ta—F stretching vibrations appearing as the infrared band at 723 cm⁻¹.

Computing details

For all structures, data collection: Bruker APEX2; cell refinement: Bruker SAINT; data reduction: Bruker SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2014); molecular graphics: Bruker SHELXTL; software used to prepare material for publication: Bruker SHELXTL.

ammonium heptafluorotantalate (I)

Crystal data

F7Ta·H8N2	Dx = 3.198 Mg m^−3
Mr = 350.03	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4/nmm	Cell parameters from 7755 reflections
a = 5.8613 (2) Å	θ = 3.5–40.1°
c = 10.5817 (3) Å	µ = 15.19 mm^−1
V = 363.53 (3) Å^3	T = 120 K
Z = 2	Sphere, colourless
F(000) = 316	0.25 × 0.25 × 0.25 mm

Data collection

Bruker APEX-II CCD diffractometer	710 reflections with I > 2σ(I)
Detector resolution: 8.33 pixels mm^-1	Rint = 0.033
φ and ω scans	θmax = 40.1°, θmin = 3.9°
Absorption correction: multi-scan Bruker SADABS	h = −9→10
Tmin = 0.116, Tmax = 0.116	k = −10→9
8074 measured reflections	l = −18→19
712 independent reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.012	Only H-atom displacement parameters refined
wR(F^2) = 0.031	w = 1/[σ^2(Fo^2) + (0.0086P)^2 + 0.8194P] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max = 0.006
712 reflections	Δρmax = 1.40 e Å^−3
30 parameters	Δρmin = −1.26 e Å^−3
0 restraints	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0070 (4)

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ta1	0.2500	0.2500	0.26030 (2)	0.00887 (2)
N1	0.2500	0.7500	0.5000	0.0142 (3)
N2	0.2500	0.2500	0.8658 (3)	0.0350 (8)
F1	0.2500	0.2500	0.44913 (14)	0.0146 (3)
F2	0.02111 (13)	0.47889 (13)	0.30015 (14)	0.0341 (3)
F3	0.1764 (6)	0.4341 (5)	0.1132 (2)	0.0357 (8)	0.25
H1	0.2500	0.8478	0.5385	0.074 (14)*
H2	0.2500	0.2500	0.9357	0.12 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ta1	0.01037 (2)	0.01037 (2)	0.00586 (3)	0.000	0.000	0.000
N1	0.0162 (5)	0.0162 (5)	0.0101 (6)	0.000	0.000	0.000
N2	0.0483 (12)	0.0483 (12)	0.0083 (8)	0.000	0.000	0.000
F1	0.0180 (4)	0.0180 (4)	0.0077 (5)	0.000	0.000	0.000
F2	0.0234 (3)	0.0234 (3)	0.0555 (7)	0.0132 (4)	−0.0004 (3)	0.0004 (3)
F3	0.061 (2)	0.0370 (13)	0.0095 (7)	0.0245 (12)	0.0052 (9)	0.0086 (8)

Geometric parameters (Å, º)

Ta1—F3	1.943 (2)	N2—F2^xiii	2.852 (2)
Ta1—F3^i	1.943 (2)	N2—F3^xviii	2.864 (3)
Ta1—F3^ii	1.943 (2)	N2—F3^xix	2.864 (3)
Ta1—F3^iii	1.943 (2)	N2—F3^xx	2.864 (3)
Ta1—F3^iv	1.943 (2)	N2—F3^xxi	2.864 (3)
Ta1—F3^v	1.943 (2)	N2—F3^xxii	2.864 (3)
Ta1—F3^vi	1.943 (2)	N2—F3^xxiii	2.864 (3)
Ta1—F3^vii	1.943 (2)	N2—H2	0.7397
Ta1—F2^vii	1.9436 (11)	F1—F2^ii	2.4668 (16)
Ta1—F2^ii	1.9436 (11)	F1—F2^iv	2.4668 (16)
N1—F2	2.9660 (11)	F1—F2^vii	2.4668 (16)
N1—F2^viii	2.9660 (11)	F1—F2	2.4668 (16)
N1—F2^ix	2.9660 (11)	F1—N1^xiv	2.9797 (3)
N1—F2^vii	2.9660 (11)	F1—N1^xiii	2.9797 (3)
N1—F2^x	2.9660 (11)	F1—N1^xxiv	2.9797 (3)
N1—F2^xi	2.9660 (11)	F2—F3^iii	2.194 (3)
N1—F2^xii	2.9660 (11)	F2—F3	2.194 (3)
N1—F2^xiii	2.9660 (11)	F2—F3^ii	2.669 (3)
N1—F1^xiv	2.9797 (3)	F2—F3^vi	2.669 (3)
N1—F1^xv	2.9797 (3)	F2—F2^vii	2.6832 (15)
N1—H1	0.7033	F2—F2^ii	2.6832 (15)
N2—F2^xvi	2.852 (2)	F2—N2^xiii	2.852 (2)
N2—F2^ix	2.852 (2)	F3—F3^iv	2.324 (6)
N2—F2^xvii	2.852 (2)	F3—F2^vii	2.669 (3)
F3—Ta1—F3^i	67.50 (18)	F2^x—N1—F2^xi	91.36 (4)
F3—Ta1—F3^iv	73.49 (17)	F2—N1—F2^xii	89.04 (4)
F3^i—Ta1—F3^vi	73.49 (17)	F2^viii—N1—F2^xii	91.36 (4)
F3^ii—Ta1—F3^vi	66.70 (17)	F2^ix—N1—F2^xii	120.56 (2)
F3^ii—Ta1—F3^vii	73.49 (17)	F2^vii—N1—F2^xii	64.79 (4)
F3^iii—Ta1—F3^vii	67.50 (18)	F2—N1—F2^xiii	91.36 (4)
F3—Ta1—F2^vii	86.76 (11)	F2^viii—N1—F2^xiii	89.04 (4)
F3^v—Ta1—F2^vii	86.76 (11)	F2^ix—N1—F2^xiii	64.79 (4)
F3^vi—Ta1—F2^vii	68.73 (9)	F2^vii—N1—F1^xiv	71.57 (3)
F3^vii—Ta1—F2^vii	68.73 (9)	F2^xii—N1—F1^xiv	71.57 (3)
F3^i—Ta1—F2^ii	68.73 (9)	F1^xiv—N1—F1^xv	91.870 (10)
F3^ii—Ta1—F2^ii	68.73 (9)	F2^ix—N1—H1	87.5
F3^iii—Ta1—F2^ii	86.76 (11)	F2^xi—N1—H1	88.7
F3^iv—Ta1—F2^ii	86.76 (11)	F2^xii—N1—H1	88.7
F2^ix—N1—F2^vii	91.36 (4)	F2^xiii—N1—H1	87.5
F2^viii—N1—F2^x	64.79 (4)	F1^xiv—N1—H1	84.0
F2^ix—N1—F2^x	89.04 (4)	F1^xv—N1—H1	45.8
F2^vii—N1—F2^xi	89.04 (4)

Symmetry codes: (i) x, −y+1/2, z; (ii) −y+1/2, x, z; (iii) −y+1/2, −x+1/2, z; (iv) −x+1/2, −y+1/2, z; (v) y, x, z; (vi) −x+1/2, y, z; (vii) y, −x+1/2, z; (viii) x+1/2, y+1/2, −z+1; (ix) −y+1, x+1/2, −z+1; (x) y−1/2, −x+1, −z+1; (xi) −y+1/2, x+1, z; (xii) −x+1/2, −y+3/2, z; (xiii) −x, −y+1, −z+1; (xiv) −x+1, −y+1, −z+1; (xv) x, y+1, z; (xvi) y−1/2, −x, −z+1; (xvii) x+1/2, y−1/2, −z+1; (xviii) −x+1/2, y, z+1; (xix) y, −x+1/2, z+1; (xx) y, x, z+1; (xxi) x, y, z+1; (xxii) −y+1/2, −x+1/2, z+1; (xxiii) −x+1/2, −y+1/2, z+1; (xxiv) x, y−1, z.

rubidium heptafluorotantalate (II-LT)

Crystal data

(F7Ta)·2(Rb)	Dx = 4.468 Mg m^−3
Mr = 484.89	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Cmma	Cell parameters from 512 reflections
a = 8.2419 (5) Å	θ = 3.9–32.1°
b = 8.2749 (5) Å	µ = 28.72 mm^−1
c = 10.5694 (7) Å	T = 123 K
V = 720.84 (8) Å^3	Prism, colorless
Z = 4	0.26 × 0.14 × 0.14 mm
F(000) = 840

Data collection

Bruker P4 diffractometer	661 reflections with I > 2σ(I)
Detector resolution: 8.33 pixels mm^-1	Rint = 0.038
ω scans	θmax = 32.1°, θmin = 3.9°
Absorption correction: multi-scan SADABS v.2.03; Bruker 1999	h = −11→12
Tmin = 0.050, Tmax = 0.108	k = −11→12
4382 measured reflections	l = −15→15
693 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.022	w = 1/[σ^2(Fo^2) + (0.0298P)^2 + 5.6867P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.060	(Δ/σ)max < 0.001
S = 1.15	Δρmax = 2.23 e Å^−3
693 reflections	Δρmin = −3.30 e Å^−3
39 parameters	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
6 restraints	Extinction coefficient: 0.0013 (2)

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ta1	0.0000	0.7500	0.24367 (2)	0.01309 (13)
Rb1	0.2500	0.5000	0.0000	0.01505 (16)
Rb2	0.0000	0.7500	0.63582 (7)	0.02155 (18)
F1	0.0000	0.7500	0.0548 (4)	0.0181 (9)
F2	0.0000	0.5222 (5)	0.2033 (4)	0.0283 (8)
F3	0.1029 (8)	0.6509 (9)	0.3895 (4)	0.0378 (15)	0.5
F4	0.2286 (5)	0.7500	0.2014 (4)	0.0277 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ta1	0.01576 (18)	0.01582 (18)	0.00769 (16)	0.000	0.000	0.000
Rb1	0.0161 (3)	0.0167 (3)	0.0123 (3)	0.000	0.000	0.000
Rb2	0.0272 (4)	0.0289 (4)	0.0086 (3)	0.000	0.000	0.000
F1	0.023 (2)	0.024 (2)	0.0076 (18)	0.000	0.000	0.000
F2	0.036 (2)	0.0187 (17)	0.030 (2)	0.000	0.000	0.0026 (15)
F3	0.050 (3)	0.055 (4)	0.008 (2)	0.029 (3)	−0.005 (2)	0.006 (2)
F4	0.0167 (16)	0.040 (2)	0.0269 (19)	0.000	−0.0018 (14)	0.000

Geometric parameters (Å, º)

Ta1—F2	1.933 (4)	Rb2—F3^ix	3.385 (7)
Ta1—F2^i	1.933 (4)	F1—F4	2.440 (5)
Ta1—F4^i	1.936 (4)	F1—F4^i	2.440 (5)
Ta1—F4	1.936 (4)	F1—F2	2.453 (5)
Ta1—F3	1.941 (5)	F1—F2^i	2.453 (5)
Ta1—F3^ii	1.941 (5)	F1—Rb1^iv	2.9766 (9)
Ta1—F3^i	1.941 (5)	F1—Rb1^vii	2.9766 (9)
Ta1—F3^iii	1.941 (5)	F1—Rb1^xiii	2.9766 (9)
Ta1—F1	1.997 (4)	F1—F4^xiv	3.512 (5)
Ta1—Rb1^iv	3.8933 (2)	F2—F3	2.393 (7)
Rb1—F4	2.974 (3)	F2—F3^iii	2.393 (7)
Rb1—F4^v	2.974 (3)	F2—F4	2.665 (4)
Rb1—F4^vi	2.974 (3)	F2—F4^i	2.665 (4)
Rb1—F4^vii	2.974 (3)	F2—Rb2^xii	2.822 (4)
Rb1—F1^iv	2.9766 (9)	F2—Rb1^iv	2.983 (3)
Rb1—F1	2.9766 (9)	F2—F4^xv	3.174 (4)
Rb1—F1^vii	2.9766 (9)	F3—F3^ii	1.640 (15)
Rb1—F1^viii	2.9766 (9)	F3—F3^iii	1.696 (14)
Rb1—F2	2.983 (3)	F3—F3^i	2.359 (12)
Rb1—F2^iv	2.983 (3)	F3—F4	2.387 (7)
Rb2—F4^ix	2.822 (4)	F3—F3^xvi	3.367 (11)
Rb2—F4^x	2.822 (4)	F3—Rb2^ix	3.385 (7)
Rb2—F2^xi	2.822 (4)	F3—F3^xvii	3.420 (12)
Rb2—F2^xii	2.822 (4)	F4—F3^ii	2.387 (7)
Rb2—F3^iii	2.858 (5)	F4—F2^i	2.665 (4)
Rb2—F3^i	2.858 (5)	F4—Rb2^ix	2.822 (4)
Rb2—F3^ii	2.858 (5)	F4—Rb1^vii	2.974 (3)
Rb2—F3	2.858 (5)	F4—F2^xviii	3.174 (4)
Rb2—F3^x	3.385 (7)
F2—Ta1—F4^i	87.08 (4)	F4^i—Ta1—F3^i	76.0 (2)
F2^i—Ta1—F4^i	87.08 (4)	F4^i—Ta1—F3^iii	76.0 (2)
F2—Ta1—F4	87.08 (4)	F3^ii—Ta1—F3^iii	74.8 (4)
F2^i—Ta1—F4	87.08 (4)	F2—Ta1—F1	77.25 (12)
F4^i—Ta1—F4	153.3 (2)	F2^i—Ta1—F1	77.25 (12)
F2—Ta1—F3	76.3 (2)	F4^i—Ta1—F1	76.67 (11)
F4—Ta1—F3	76.0 (2)	F4—Ta1—F1	76.67 (11)
F2^i—Ta1—F3^ii	76.3 (2)	F3^iii—Ta1—Rb1^iv	93.99 (18)
F4—Ta1—F3^ii	76.0 (2)	F1—Ta1—Rb1^iv	48.586 (4)
F2^i—Ta1—F3^i	76.3 (2)

Symmetry codes: (i) −x, −y+3/2, z; (ii) x, −y+3/2, z; (iii) −x, y, z; (iv) −x, −y+1, −z; (v) x, y−1/2, −z; (vi) −x+1/2, −y+1, z; (vii) −x+1/2, −y+3/2, −z; (viii) x+1/2, y−1/2, z; (ix) −x+1/2, −y+3/2, −z+1; (x) x−1/2, y, −z+1; (xi) x, y+1/2, −z+1; (xii) −x, −y+1, −z+1; (xiii) x−1/2, y+1/2, z; (xiv) x−1/2, y, −z; (xv) x−1/2, y−1/2, z; (xvi) −x+1/2, y, −z+1; (xvii) x, −y+1, −z+1; (xviii) x+1/2, y+1/2, z.

rubidium heptafluorotantalate (II-RT)

Crystal data

(F7Ta)·Rb2	Dx = 4.340 Mg m^−3
Mr = 484.89	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4/nmm	Cell parameters from 512 reflections
a = 5.9118 (3) Å	θ = 3.8–38.0°
c = 10.6173 (10) Å	µ = 27.90 mm^−1
V = 371.07 (5) Å^3	T = 297 K
Z = 2	Prism, colorless
F(000) = 420	0.26 × 0.14 × 0.14 mm

Data collection

Bruker P4 diffractometer	562 reflections with I > 2σ(I)
Detector resolution: 8.33 pixels mm^-1	Rint = 0.044
ω scans	θmax = 38.0°, θmin = 3.8°
Absorption correction: multi-scan Bruker SADABS	h = −10→8
Tmin = 0.052, Tmax = 0.112	k = −10→10
9610 measured reflections	l = −18→18
638 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.023	w = 1/[σ^2(Fo^2) + (0.0244P)^2 + 0.6642P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.058	(Δ/σ)max < 0.001
S = 1.18	Δρmax = 1.51 e Å^−3
638 reflections	Δρmin = −1.89 e Å^−3
28 parameters	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0205 (13)

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ta1	0.2500	0.2500	0.25483 (2)	0.02409 (10)
Rb1	0.2500	0.7500	0.5000	0.02940 (15)
Rb2	0.2500	0.2500	0.86308 (8)	0.0425 (2)
F1	0.2500	0.2500	0.4444 (4)	0.0378 (11)
F2	0.0243 (4)	0.4757 (4)	0.2991 (3)	0.0518 (8)
F3	0.204 (5)	0.4466 (14)	0.1096 (5)	0.067 (9)	0.25

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ta1	0.02581 (12)	0.02581 (12)	0.02066 (13)	0.000	0.000	0.000
Rb1	0.0294 (2)	0.0294 (2)	0.0294 (3)	0.000	0.000	0.000
Rb2	0.0520 (3)	0.0520 (3)	0.0234 (3)	0.000	0.000	0.000
F1	0.0461 (18)	0.0461 (18)	0.0213 (18)	0.000	0.000	0.000
F2	0.0447 (11)	0.0447 (11)	0.0660 (19)	0.0183 (14)	−0.0005 (9)	0.0005 (9)
F3	0.13 (3)	0.052 (4)	0.024 (2)	0.035 (10)	0.007 (4)	0.014 (2)

Geometric parameters (Å, º)

Ta1—F2^i	1.945 (3)	Rb2—F2^ix	2.868 (3)
Ta1—F2^ii	1.945 (3)	Rb2—F3^xix	2.877 (7)
Ta1—F2^iii	1.945 (3)	Rb2—F3^xx	2.877 (7)
Ta1—F2	1.945 (3)	Rb2—F3^xxi	2.877 (7)
Ta1—F3^iv	1.949 (8)	Rb2—F3^xxii	2.877 (7)
Ta1—F3^ii	1.949 (8)	Rb2—F3^xxiii	2.877 (7)
Ta1—F3^v	1.949 (8)	Rb2—F3^xxiv	2.877 (7)
Ta1—F3^iii	1.949 (8)	Rb2—F3^xxv	2.877 (7)
Ta1—F3^vi	1.949 (8)	Rb2—F3^xxvi	2.877 (7)
Ta1—F3^vii	1.949 (8)	Rb2—F3^xxvii	3.24 (3)
Ta1—F3^i	1.949 (8)	Rb2—F3^xii	3.24 (3)
Ta1—F3	1.949 (8)	Rb2—F3^xvii	3.24 (3)
Ta1—F1	2.013 (5)	Rb2—F3^xxviii	3.24 (3)
Ta1—Rb1^viii	3.9387 (3)	Rb2—F3^xxix	3.24 (3)
Ta1—Rb1	3.9387 (3)	Rb2—F3^xviii	3.24 (3)
Ta1—Rb1^ix	3.9387 (3)	Rb2—F3^xxx	3.24 (3)
Ta1—Rb1^x	3.9387 (3)	Rb2—F3^ix	3.24 (3)
Rb1—F2	2.993 (3)	F1—F2^ii	2.437 (4)
Rb1—F2^xi	2.993 (3)	F1—F2^iii	2.437 (4)
Rb1—F2^xii	2.993 (3)	F1—F2^i	2.437 (4)
Rb1—F2^i	2.993 (3)	F1—F2	2.437 (4)
Rb1—F2^xiii	2.993 (3)	F1—Rb1^viii	3.0143 (9)
Rb1—F2^xiv	2.993 (3)	F1—Rb1^ix	3.0143 (9)
Rb1—F2^ix	2.993 (3)	F1—Rb1^x	3.0143 (9)
Rb1—F2^xv	2.993 (3)	F2—F3	2.282 (16)
Rb1—F1^viii	3.0143 (9)	F2—F3^v	2.282 (16)
Rb1—F1^ix	3.0143 (9)	F2—F3^ii	2.58 (2)
Rb1—F1^xvi	3.0143 (9)	F2—F3^vii	2.58 (2)
Rb1—F1	3.0143 (9)	F2—F2^i	2.669 (4)
Rb1—Ta1^viii	3.9387 (3)	F2—F2^ii	2.669 (4)
Rb1—Ta1^xvi	3.9387 (3)	F3—F3^iv	2.324 (17)
Rb1—Ta1^ix	3.9387 (3)	F3—F3^iii	2.39 (2)
Rb2—F2^xvii	2.868 (3)	F3—F2^i	2.58 (2)
Rb2—F2^xii	2.868 (3)	F3—Rb2^xxxi	2.877 (7)
Rb2—F2^xviii	2.868 (3)
F2^i—Ta1—F2^ii	152.0 (2)	F3^vi—Ta1—F3^vii	51.3 (4)
F2^i—Ta1—F2^iii	86.65 (5)	F2^i—Ta1—F3^i	71.8 (7)
F2^ii—Ta1—F2^iii	86.65 (5)	F2^iii—Ta1—F3^i	83.0 (7)
F2^i—Ta1—F2	86.65 (5)	F2—Ta1—F3^i	120.3 (8)
F2^ii—Ta1—F2	86.65 (5)	F3^iv—Ta1—F3^i	62.6 (14)
F2^ii—Ta1—F3^iv	71.8 (7)	F3^ii—Ta1—F3^i	75.5 (6)
F2^iii—Ta1—F3^iv	83.0 (7)	F3^v—Ta1—F3^i	73.2 (5)
F2^ii—Ta1—F3^ii	71.8 (7)	F2^i—Ta1—F3	83.0 (7)
F2—Ta1—F3^ii	83.0 (7)	F2—Ta1—F3	71.8 (6)
F2^ii—Ta1—F3^v	83.0 (7)	F3^iv—Ta1—F3	73.2 (5)
F2—Ta1—F3^v	71.8 (7)	F3^ii—Ta1—F3	51.3 (4)
F2^ii—Ta1—F3^iii	83.0 (7)	F3^v—Ta1—F3	37.7 (15)
F2^iii—Ta1—F3^iii	71.8 (6)	F3^iii—Ta1—F3	75.5 (6)
F3^v—Ta1—F3^iii	62.6 (14)	F3^vi—Ta1—F3	62.6 (14)
F2^i—Ta1—F3^vi	83.0 (7)	F3^vii—Ta1—F3	16.0 (18)
F2—Ta1—F3^vii	83.0 (7)	F3^i—Ta1—F3	51.3 (4)
F3^iv—Ta1—F3^vii	75.5 (6)	F2^i—Ta1—F1	76.01 (11)
F3^ii—Ta1—F3^vii	62.6 (14)	F2^ii—Ta1—F1	76.01 (11)
F3^v—Ta1—F3^vii	51.3 (4)	F2^iii—Ta1—F1	76.01 (11)
F3^iii—Ta1—F3^vii	73.2 (5)	F2—Ta1—F1	76.01 (11)

Symmetry codes: (i) y, −x+1/2, z; (ii) −y+1/2, x, z; (iii) −x+1/2, −y+1/2, z; (iv) x, −y+1/2, z; (v) −y+1/2, −x+1/2, z; (vi) y, x, z; (vii) −x+1/2, y, z; (viii) −x+1, −y+1, −z+1; (ix) −x, −y+1, −z+1; (x) x, y−1, z; (xi) x+1/2, y+1/2, −z+1; (xii) −y+1, x+1/2, −z+1; (xiii) y−1/2, −x+1, −z+1; (xiv) −y+1/2, x+1, z; (xv) −x+1/2, −y+3/2, z; (xvi) x, y+1, z; (xvii) y−1/2, −x, −z+1; (xviii) x+1/2, y−1/2, −z+1; (xix) −x+1/2, y, z+1; (xx) y, −x+1/2, z+1; (xxi) y, x, z+1; (xxii) x, y, z+1; (xxiii) −y+1/2, −x+1/2, z+1; (xxiv) −x+1/2, −y+1/2, z+1; (xxv) x, −y+1/2, z+1; (xxvi) −y+1/2, x, z+1; (xxvii) x+1/2, −y+1, −z+1; (xxviii) −x, y−1/2, −z+1; (xxix) y−1/2, x+1/2, −z+1; (xxx) −y+1, −x, −z+1; (xxxi) x, y, z−1.

(III)

Crystal data

(OF6Ta)·3Rb	Mo Kα radiation, λ = 0.71073 Å
Mr = 567.36	Cell parameters from 3898 reflections
Cubic, Fm3m	θ = 3.8–37.5°
a = 9.1842 (2) Å	µ = 32.96 mm^−1
V = 774.68 (5) Å^3	T = 293 K
Z = 4	Plate, colourless
F(000) = 984	0.25 × 0.25 × 0.13 mm
Dx = 4.865 Mg m^−3

Data collection

Bruker APEX-II CCD diffractometer	204 reflections with I > 2σ(I)
Detector resolution: 8.33 pixels mm^-1	Rint = 0.039
φ and ω scans	θmax = 44.8°, θmin = 3.8°
Absorption correction: multi-scan Bruker SADABS	h = −18→17
Tmin = 0.045, Tmax = 0.100	k = −17→18
5883 measured reflections	l = −18→17
204 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.010	w = 1/[σ^2(Fo^2) + 1.7182P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.020	(Δ/σ)max = 0.018
S = 1.06	Δρmax = 0.83 e Å^−3
204 reflections	Δρmin = −0.51 e Å^−3
27 parameters	Extinction correction: SHELXL-2014/7 (Sheldrick 2014, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.00043 (7)

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ta1	0.0000	0.0000	0.0000	0.007 (14)	0.03 (5)
Ta2	0.0000	0.0000	0.0169 (6)	0.0078 (4)	0.162 (9)
Rb1	0.26262 (12)	0.26262 (12)	0.26262 (12)	0.0274 (4)	0.25
Rb2	0.5000	0.5000	0.5000	0.0382 (2)	0.947 (4)
F1	0.0000	0.0000	0.2103 (9)	0.037 (2)	0.5
F2	0.0000	0.0595 (15)	0.2051 (17)	0.041 (5)	0.0833
F3	0.0000	0.1272 (13)	0.1859 (18)	0.046 (7)	0.0833

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ta1	0.007 (14)	0.007 (14)	0.007 (14)	0.000	0.000	0.000
Ta2	0.0094 (4)	0.0094 (4)	0.0046 (6)	0.000	0.000	0.000
Rb1	0.0274 (4)	0.0274 (4)	0.0274 (4)	−0.0004 (2)	−0.0004 (2)	−0.0004 (2)
Rb2	0.0382 (2)	0.0382 (2)	0.0382 (2)	0.000	0.000	0.000
F1	0.051 (3)	0.051 (3)	0.0097 (13)	0.000	0.000	0.000
F2	0.043 (6)	0.058 (16)	0.021 (5)	0.000	0.000	−0.009 (10)
F3	0.039 (5)	0.060 (12)	0.039 (11)	0.000	0.000	−0.033 (11)

Geometric parameters (Å, º)

Ta1—F1^i	1.932 (9)	Rb1—F3^xiv	2.505 (7)
Ta1—F1^ii	1.932 (9)	Rb1—F3^xv	2.505 (7)
Ta1—F1^iii	1.932 (9)	Rb1—F3^xvi	2.505 (7)
Ta1—F1^iv	1.932 (9)	Rb1—F3^xvii	2.554 (6)
Ta1—F1^v	1.932 (9)	Rb1—F3^xviii	2.554 (6)
Ta1—F1	1.932 (9)	Rb1—F3^xix	2.554 (6)
Ta1—F2	1.961 (15)	Rb2—F1^xx	2.660 (9)
Ta2—F1	1.777 (10)	Rb2—F1^xxi	2.660 (9)
Ta2—F2	1.813 (16)	Rb2—F1^xxii	2.660 (9)
Ta2—F2^vi	1.813 (16)	Rb2—F1^xxiii	2.660 (9)
Ta2—F2^vii	1.813 (16)	Rb2—F1^xxiv	2.660 (9)
Ta2—F2^viii	1.813 (16)	Rb2—F1^xxv	2.660 (9)
Ta2—F2^ix	1.924 (15)	Rb2—F2^xxvi	2.763 (15)
Ta2—F2^iv	1.924 (15)	Rb2—F2^xiii	2.763 (15)
Rb1—Rb1^x	0.328 (3)	Rb2—F2^xxvii	2.763 (15)
Rb1—F3^xi	2.505 (7)	Rb2—F2^xii	2.763 (15)
Rb1—F3^xii	2.505 (7)	Rb2—F2^xxviii	2.763 (15)
Rb1—F3^xiii	2.505 (7)	Rb2—F2^xv	2.763 (15)
Ta2^v—Ta1—F1^ii	90.0	F1^i—Ta1—F1^iv	90.0
F1^i—Ta1—F1^ii	180.0	F1^ii—Ta1—F1^iv	90.0
F1^i—Ta1—F1^iii	90.0	F1^iii—Ta1—F1^iv	180.0
F1^ii—Ta1—F1^iii	90.0	F2^viii—Ta2—F2^ix	95.8 (2)
Ta2^i—Ta1—F1^iv	90.0	F2—Ta2—F2^iv	78.8 (4)

Symmetry codes: (i) −y, −z, −x; (ii) y, z, x; (iii) −z, −x, −y; (iv) z, x, y; (v) −x, −y, −z; (vi) y, x, z; (vii) −y, −x, z; (viii) −x, −y, z; (ix) −x, z, y; (x) x, −y+1/2, −z+1/2; (xi) z, −y+1/2, x+1/2; (xii) −y+1/2, z, −x+1/2; (xiii) x+1/2, z, −y+1/2; (xiv) −y+1/2, −x+1/2, z; (xv) z, −x+1/2, −y+1/2; (xvi) −x+1/2, −y+1/2, z; (xvii) −z+1/2, y, −x+1/2; (xviii) −x+1/2, −z+1/2, y; (xix) y, x+1/2, −z+1/2; (xx) −y+1/2, −z+1, −x+1/2; (xxi) y+1/2, z, x+1/2; (xxii) −z+1, −x+1/2, −y+1/2; (xxiii) z, x+1/2, y+1/2; (xxiv) −x+1/2, −y+1/2, −z+1; (xxv) x+1/2, y+1/2, z; (xxvi) −x+1/2, −z+1, y+1/2; (xxvii) y+1/2, −z+1, x+1/2; (xxviii) −z+1, x+1/2, y+1/2.