Orientational disorder in crystals of (NH₄)₃MoO₃F₃ and (NH₄)₃WO₃F₃

Triammonium trioxotrifluoromolybdate (NH₄)₃MoO₃F₃ (I) and trioxotrifluorotungstate (NH₄)₃WO₃F₃ (II) were synthesized in a single-crystal form and their structures were refined by X-ray diffraction. These two isostructural compounds belong to the elpasolite-type structure (cubic system, space group Fm3m, Z = 4). O and F atoms are randomly distributed in two independent positions [24(e) and 96(j)] of the cubic unit cell, and the central atoms and the ammonium cation containing N2 are shifted from the symmetry centers into the 32(f) position. As a consequence, O and F atoms in the equilibrium structure were identified on a local scale by the metal-ligand distance and hydrogen atomic coordinates of the disordered ammonium cation N2H₄ were determined. The slightly compressed MX₆ (M = Mo, W; X = O, F) octahedron has a fac configuration with the central atom shifted toward the face occupied by three O atoms. The true geometry of this polyhedron permits us to explain the observed vibrational spectra of the compounds examined and to eliminate the contradiction in interpretation of the vibrational spectra of [MO₃F₃]^n- species reported in the literature. Both complexes reveal a dynamic disordering: the [MX₆]^3- anions are disordered on 48 equivalent orientations and the N2H₄ groups have eight orientations.

Computing details

For both compounds, data collection: Bruker Smart v5.054 (Bruker, 1998); cell refinement: Bruker SAINT v6.02a (Bruker, 2000); data reduction: Bruker SAINT v6.02a (Bruker, 2000); program(s) used to solve structure: Bruker SHELXTL v5.1 (Bruker, 1998); program(s) used to refine structure: Bruker SHELXTL v5.1 (Bruker, 1998); molecular graphics: Bruker SHELXTL v5.1 (Bruker, 1998); software used to prepare material for publication: Bruker SHELXTL v5.1 (Bruker, 1998).

Figures

(I) ammonium trifluorotrioxomolybdate(VI)

Crystal data

(F3O3Mo)·3(NH4)	Dx = 2.226 Mg m^−3
Mr = 255.07	Mo Kα radiation, λ = 0.71073 Å
Cubic, Fm3m	Cell parameters from 787 reflections
Hall symbol: -F 4 2 3	θ = 3.9–30.7°
a = 9.1295 (3) Å	µ = 1.74 mm^−1
V = 760.92 (4) Å^3	T = 297 K
Z = 4	Octahedron, colorless
F(000) = 504	0.33 × 0.25 × 0.17 mm

Data collection

Bruker Smart 1000 CCD diffractometer	89 independent reflections
Radiation source: fine-focus sealed tube	85 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
Detector resolution: 8.33 pixels mm^-1	θmax = 30.7°, θmin = 3.9°
ω scans	h = −13→12
Absorption correction: multi-scan SADABS v.2.03; Bruker 1999	k = −13→12
Tmin = 0.597, Tmax = 0.756	l = −13→13
2016 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.017	H-atom parameters not refined
wR(F^2) = 0.053	w = 1/[σ^2(Fo^2) + (0.0331P)^2 + 0.460P] where P = (Fo^2 + 2Fc^2)/3
S = 1.24	(Δ/σ)max = 0.042
89 reflections	Δρmax = 0.17 e Å^−3
18 parameters	Δρmin = −0.20 e Å^−3
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0417 (6)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Mo	0.019853 (10)	0.019853 (10)	0.019853 (10)	0.02880 (6)	0.12
N1	0.2500	0.2500	0.2500	0.0590 (3)
N2	0.51626 (16)	0.51626 (16)	0.51626 (16)	0.0582 (8)	0.12
F1	0.0000	0.0000	0.20034 (13)	0.0823 (6)	0.17
O1	0.0000	0.0000	0.20034 (13)	0.0823 (6)	0.17
F2	0.0000	0.06177 (18)	0.19835 (17)	0.1035 (6)	0.08
O2	0.0000	0.06177 (18)	0.19835 (17)	0.1035 (6)	0.08
H1	0.1990	0.1990	0.1990	0.125*
H2	0.6044	0.5000	0.5000	0.075*	0.50
H3	0.4638	0.4638	0.4638	0.125*	0.12

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Mo	0.02880 (6)	0.02880 (6)	0.02880 (6)	−0.00202 (4)	−0.00202 (4)	−0.00202 (4)
N1	0.0590 (3)	0.0590 (3)	0.0590 (3)	0.000	0.000	0.000
N2	0.0582 (8)	0.0582 (8)	0.0582 (8)	−0.0123 (12)	−0.0123 (12)	−0.0123 (12)
F1	0.1185 (8)	0.1185 (8)	0.0098 (4)	0.000	0.000	0.000
O1	0.1185 (8)	0.1185 (8)	0.0098 (4)	0.000	0.000	0.000
F2	0.0742 (10)	0.1760 (15)	0.0602 (6)	0.000	0.000	−0.0656 (6)
O2	0.0742 (10)	0.1760 (15)	0.0602 (6)	0.000	0.000	−0.0656 (6)

Geometric parameters (Å, º)

Mo—Mo^i	0.3626 (2)	N2—N2^xxviii	0.295 (3)
Mo—Mo^ii	0.3627 (2)	N2—N2^xxix	0.295 (3)
Mo—Mo^iii	0.3626 (2)	N2—N2^xxx	0.295 (3)
Mo—Mo^iv	0.5128 (2)	N2—N2^xxxi	0.417 (4)
Mo—Mo^v	0.5129 (2)	N2—N2^xxxii	0.417 (4)
Mo—Mo^vi	0.5129 (2)	N2—N2^xxxiii	0.417 (4)
Mo—Mo^vii	0.6281 (3)	N2—N2^xxxiv	0.511 (5)
Mo—F1	1.6674 (11)	N2—O1^xxxv	2.5967 (16)
Mo—O1^viii	1.6674 (11)	N2—F1^xxxv	2.5967 (16)
Mo—F2	1.6846 (15)	N2—O2^xxxvi	2.643 (2)
Mo—O2^ix	1.6846 (15)	N2—F2^xxxvii	2.643 (2)
Mo—O2^x	1.8020 (15)	N2—O2^xxxviii	2.7050 (17)
Mo—F2^xi	1.8020 (15)	N2—F2^xxxix	2.7050 (17)
Mo—O1^vii	2.0265 (11)	N2—O1^xl	2.8909 (19)
Mo—F1^vii	2.0265 (11)	N2—F1^xl	2.8909 (19)
Mo—O2^i	2.0376 (15)	N2—O2^xli	2.9341 (19)
Mo—F2^xii	2.0376 (15)	N2—F2^xlii	2.9341 (19)
Mo—F2^vii	2.1357 (15)	N2—O2^xliii	2.990 (2)
Mo—O2^xiii	2.1357 (15)	N2—F2^xliv	2.990 (2)
Mo—N1	3.6393 (2)	N2—H2	0.8319
Mo—N1^xiv	3.8599 (1)	N2—H3	0.8283
Mo—N1^xv	3.8599 (1)	F1—O2^xlv	2.6349 (14)
Mo—N1^xvi	3.8599 (1)	F1—O2^xlvi	2.6349 (14)
Mo—N1^xvii	4.0686 (2)	F1—F2^xlv	2.6349 (14)
Mo—N1^xviii	4.0686 (2)	F1—F2^xlvi	2.6349 (14)
Mo—N1^xix	4.0686 (2)	F1—O2^xlvii	2.6349 (14)
Mo—N2^xx	4.2353 (15)	F1—O2^xlviii	2.6349 (14)
Mo—N2^xxi	4.2353 (15)	F1—F2^xlvii	2.6349 (14)
Mo—N2^xxii	4.2353 (15)	F1—F2^xlviii	2.6349 (14)
Mo—N2^xxiii	4.2480 (14)	F1—O2^xi	2.6349 (14)
Mo—N2^xxiv	4.2480 (14)	F1—O2^x	2.6349 (14)
Mo—N2^xxv	4.2480 (14)	F1—F2^xi	2.6349 (14)
N1—O2^ix	2.8952 (10)	F1—F2^x	2.6349 (14)
N1—O2^viii	2.8952 (10)	F1—O2^ix	2.6349 (14)
N1—F2^ix	2.8952 (10)	F1—O2^viii	2.6349 (14)
N1—F2^viii	2.8952 (10)	F1—F2^ix	2.6349 (14)
N1—O2^xxvi	2.8952 (10)	F1—F2^viii	2.6349 (14)
N1—O2^xxvii	2.8952 (10)	F2—O2^xlix	2.684 (2)
N1—F2^xxvi	2.8952 (10)	F2—F2^xlix	2.684 (2)
N1—F2^xxvii	2.8952 (10)	F2—O2^l	2.684 (2)
N1—H1	0.8072	F2—F2^l	2.684 (2)
F1^xxvii—Mo—F2	103.666 (11)	F2^li—Mo—O2^xii	162.521 (17)
F1—Mo—O2^ix	103.666 (11)	O1^xlvi—Mo—O2^xii	80.854 (8)
O2^viii—Mo—O2^xi	100.601 (11)	F1^xlvi—Mo—O2^xii	80.854 (8)
F2^viii—Mo—O2^xi	100.601 (11)	F2^xxvii—Mo—F2^xii	91.769 (10)
F1—Mo—F2^xi	98.790 (10)	O2^xxvi—Mo—F2^i	91.769 (10)
F1—Mo—O2^x	98.790 (10)	O1^viii—Mo—O2^xiii	86.820 (8)
F1—Mo—O1^vii	163.892 (14)	F1^viii—Mo—O2^xiii	86.820 (8)
F1—Mo—F1^vii	163.892 (14)	O2^lii—Mo—O2^xiii	166.766 (14)
O2^ix—Mo—O1^vii	90.006 (8)	F2^lii—Mo—O2^xiii	166.766 (14)
F2^viii—Mo—O1^vii	90.006 (8)	O2^liii—Mo—O2^xiii	85.480 (9)
O2^xi—Mo—O1^vii	86.795 (8)	F2^liii—Mo—O2^xiii	85.480 (9)
F2^x—Mo—O1^vii	86.795 (8)	O1^xlvi—Mo—O2^xiii	78.526 (8)
O2^xi—Mo—F1^vii	86.795 (8)	F1^xlvi—Mo—O2^xiii	78.526 (8)
O1^viii—Mo—O2^xii	90.118 (8)	O2^liv—Mo—O2^xiii	79.999 (9)
F1^viii—Mo—O2^xii	90.118 (8)	F2^liv—Mo—O2^xiii	79.999 (9)
O2^li—Mo—O2^xii	162.521 (17)

Symmetry codes: (i) x, y, −z; (ii) −x, y, z; (iii) x, −y, z; (iv) x, −y, −z; (v) −x, y, −z; (vi) −x, −y, z; (vii) −x, −y, −z; (viii) y, z, x; (ix) z, y, −x; (x) −y, z, −x; (xi) z, −y, x; (xii) y, x, −z; (xiii) −y, −x, −z; (xiv) −x+1/2, −y+1/2, −z; (xv) −x, −y+1/2, −z+1/2; (xvi) −x+1/2, −y, −z+1/2; (xvii) x, y−1/2, z−1/2; (xviii) x−1/2, y, z−1/2; (xix) x−1/2, y−1/2, z; (xx) −x+1, y−1/2, z−1/2; (xxi) x−1/2, −y+1, z−1/2; (xxii) x−1/2, y−1/2, −z+1; (xxiii) −x+1/2, −y+1, z−1/2; (xxiv) x−1/2, −y+1, −z+1/2; (xxv) −x+1, −y+1/2, z−1/2; (xxvi) −x, z, y; (xxvii) z, x, y; (xxviii) x, y, −z+1; (xxix) −x+1, y, z; (xxx) x, −y+1, z; (xxxi) x, −y+1, −z+1; (xxxii) −x+1, y, −z+1; (xxxiii) −x+1, −y+1, z; (xxxiv) −x+1, −y+1, −z+1; (xxxv) −y+1/2, −z+1, −x+1/2; (xxxvi) y+1/2, −z+1, x+1/2; (xxxvii) −z+1, y+1/2, −x+1/2; (xxxviii) −z+1, −x+1/2, −y+1/2; (xxxix) x+1/2, −z+1, −y+1/2; (xl) x+1/2, y+1/2, z; (xli) y+1/2, z, x+1/2; (xlii) z, y+1/2, −x+1/2; (xliii) z, −x+1/2, −y+1/2; (xliv) x+1/2, z, −y+1/2; (xlv) −z, −y, x; (xlvi) −y, −z, −x; (xlvii) −z, y, −x; (xlviii) y, −z, x; (xlix) −x, −z, y; (l) x, z, −y; (li) −y, −x, z; (lii) y, x, z; (liii) z, −x, −y; (liv) −z, x, y.

(II) ammonium trifluorotrioxotungstate(VI)

Crystal data

(F3O3W)·3(NH4)	Dx = 2.968 Mg m^−3
Mr = 342.98	Mo Kα radiation, λ = 0.71073 Å
Cubic, Fm3m	Cell parameters from 720 reflections
Hall symbol: -F 4 2 3	θ = 3.9–29.8°
a = 9.1563 (3) Å	µ = 15.07 mm^−1
V = 767.64 (4) Å^3	T = 297 K
Z = 4	Octahedron, colorless
F(000) = 632	0.33 × 0.25 × 0.17 mm

Data collection

Bruker Smart 1000 CCD diffractometer	83 independent reflections
Radiation source: fine-focus sealed tube	83 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.037
Detector resolution: 8.33 pixels mm^-1	θmax = 29.8°, θmin = 3.9°
ω scans	h = −12→12
Absorption correction: multi-scan SADABS v.2.03; Bruker 1999	k = −12→12
Tmin = 0.083, Tmax = 0.184	l = −12→12
2269 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.009	H-atom parameters not refined
wR(F^2) = 0.019	w = 1/[σ^2(Fo^2) + (0.0125P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.20	(Δ/σ)max = 0.032
83 reflections	Δρmax = 0.20 e Å^−3
18 parameters	Δρmin = −0.19 e Å^−3
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00265 (4)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
W1	0.012210 (5)	0.012210 (5)	0.012210 (5)	0.029930 (10)	0.12
N1	0.2500	0.2500	0.2500	0.0475 (2)
N2	0.51681 (12)	0.51681 (12)	0.51681 (12)	0.0382 (5)	0.12
F1	0.0000	0.0000	0.20062 (16)	0.1061 (9)	0.17
O1	0.0000	0.0000	0.20062 (16)	0.1061 (9)	0.17
F2	0.0000	0.0600 (2)	0.19817 (16)	0.0756 (5)	0.08
O2	0.0000	0.0600 (2)	0.19817 (16)	0.0756 (5)	0.08
H1	0.1950	0.1950	0.1950	0.220*
H2	0.6110	0.5000	0.5000	0.076*	0.50
H3	0.4630	0.4630	0.4630	0.025*	0.12

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
W1	0.029930 (10)	0.029930 (10)	0.029930 (10)	−0.00179 (3)	−0.00179 (3)	−0.00179 (3)
N1	0.0475 (2)	0.0475 (2)	0.0475 (2)	0.000	0.000	0.000
N2	0.0382 (5)	0.0382 (5)	0.0382 (5)	−0.0021 (6)	−0.0021 (6)	−0.0021 (6)
F1	0.1518 (14)	0.1518 (14)	0.0148 (5)	0.000	0.000	0.000
O1	0.1518 (14)	0.1518 (14)	0.0148 (5)	0.000	0.000	0.000
F2	0.0752 (10)	0.1081 (12)	0.0435 (5)	0.000	0.000	−0.0297 (5)
O2	0.0752 (10)	0.1081 (12)	0.0435 (5)	0.000	0.000	−0.0297 (5)

Geometric parameters (Å, º)

W1—W1^i	0.2236	N2—N2^xxiii	0.435 (3)
W1—W1^ii	0.2236	N2—N2^xxiv	0.435 (3)
W1—W1^iii	0.2236	N2—N2^xxv	0.435 (3)
W1—W1^iv	0.3162 (1)	N2—N2^xxvi	0.533 (4)
W1—W1^v	0.3162 (1)	N2—O1^xxvii	2.5964 (18)
W1—W1^vi	0.3162 (1)	N2—F1^xxvii	2.5964 (18)
W1—W1^vii	0.3873 (2)	N2—O2^xxviii	2.6440 (19)
W1—O1^viii	1.7324 (15)	N2—F2^xxviii	2.6440 (19)
W1—F1^ix	1.7324 (15)	N2—O2^xxix	2.7072 (16)
W1—O2^x	1.7615 (15)	N2—F2^xxix	2.7072 (16)
W1—F2^x	1.7615 (15)	N2—O1^xxx	2.9032 (19)
W1—O2^iv	1.8299 (15)	N2—F1^xxxi	2.9033 (19)
W1—F2^xi	1.8299 (15)	N2—O2^xxx	2.9482 (17)
W1—O1^vii	1.9552 (15)	N2—F2^xxxii	2.9483 (17)
W1—F1^xii	1.9552 (15)	N2—O2^xix	3.005 (2)
W1—O2^xiii	1.9785 (15)	N2—F2^xvii	3.005 (2)
W1—F2^xiv	1.9785 (15)	N2—H2	0.8895
W1—O2^xv	2.0396 (15)	N2—H3	0.8534
W1—F2^xvi	2.0396 (15)	F1—O2^xv	2.6398 (15)
N1—O2^xvii	2.9141 (11)	F1—F2^xv	2.6398 (15)
N1—O2^xviii	2.9141 (11)	F1—F2^xii	2.6398 (15)
N1—O2^xix	2.9141 (11)	F1—O2^xxxiii	2.6398 (15)
N1—O2^ix	2.9141 (11)	F1—O2^xxxiv	2.6398 (15)
N1—F2^xvii	2.9141 (11)	F1—F2^xxxiii	2.6398 (15)
N1—F2^xviii	2.9141 (11)	F1—F2^xxxiv	2.6398 (15)
N1—F2^xix	2.9141 (11)	F1—O2^xxxv	2.6398 (15)
N1—F2^ix	2.9141 (11)	F2—O2^xiv	2.681 (2)
N1—H1	0.8723	F2—F2^xiv	2.681 (2)
N2—N2^xx	0.308 (2)	F2—O2^xxxvi	2.681 (2)
N2—N2^xxi	0.308 (2)	F2—F2^xxxvi	2.681 (2)
N2—N2^xxii	0.308 (2)
O1^ix—W1—O2^xi	95.600 (6)	O1^xxxvii—W1—O2^xiv	84.298 (5)
F1^ix—W1—O2^xi	95.600 (6)	F1^xxxvii—W1—O2^xiv	84.298 (5)
O1^ix—W1—O2^x	98.141 (6)	O2^x—W1—O2^xiii	91.403 (6)
F1^ix—W1—O2^x	98.141 (6)	F2^x—W1—O2^xiii	91.403 (6)
O2^viii—W1—F2^xi	96.559 (6)	O2^xviii—W1—O2^xv	171.845 (9)
F2^viii—W1—F2^xi	96.559 (6)	F2^xviii—W1—O2^xv	171.845 (9)
O2^x—W1—O1^xii	90.356 (5)	O2^xxxviii—W1—O2^xv	87.538 (6)
F2^x—W1—O1^xii	90.356 (5)	F2^xxxviii—W1—O2^xv	87.538 (6)
O2^xi—W1—O1^xii	88.376 (5)	O1^vii—W1—O2^xv	82.694 (5)
F2^xi—W1—O1^xii	88.376 (5)	F1^vii—W1—O2^xv	82.694 (5)
O1^viii—W1—O1^xxxvii	170.125 (9)	O2^xxxiv—W1—O2^xv	83.694 (6)
F1^viii—W1—O1^xxxvii	170.125 (9)	F2^xxxiv—W1—O2^xv	83.694 (6)
O1^viii—W1—O2^xiv	90.442 (5)	F1^viii—W1—O2^xvi	88.437 (5)
F1^viii—W1—O2^xiv	90.442 (5)	O1^ix—W1—O2^xxxix	88.437 (5)
F2^xxxvi—W1—O2^xiv	169.214 (10)

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