Ammonium iron(III) molybdate

A new compound with an open framework, (NH₄)[Fe(MoO₄)₂], was synthesized through hydro­thermal reaction. It contains 10 non-H atoms in the asymmetric unit and the structure comprises a network of FeO₆ octahedra and MoO₄ tetrahedra that strictly alternate and involve only Fe-O-Mo linkages. The ammonium cations sit in the middle of the channels formed by these linkages.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](Fe-O) = 0.002 Å
• R factor = 0.021
• wR factor = 0.055
• Data-to-parameter ratio = 13.1

checkCIF/PLATON results

No syntax errors found



Alert level A
DIFF012_ALERT_1_A  _diffrn_reflns_av_R_equivalents is missing
            R factor for symmetry-equivalent intensities.
            The following tests will not be performed
            RINTA
DIFF020_ALERT_1_A  _diffrn_standards_interval_count and
            _diffrn_standards_interval_time are missing. Number of measurements
            between standards or time (min) between standards.
DIFF022_ALERT_1_A  _diffrn_standards_decay_% is missing
            Percentage decrease in standards intensity.

Alert level C
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?

   3 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   4 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: TEXRAY software (Molecular Structure Corporation, 1999); cell refinement: TEXRAY software; data reduction: TEXSAN (Molecular Structure Corporation, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEX (McArdle, 1995); software used to prepare material for publication: SHELXL97.

ammonium iron molybdate

Crystal data

(NH4)[Fe(MoO4)2]	F(000) = 740
Mr = 393.77	Dx = 3.556 Mg m^−3
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ac 2n	Cell parameters from 25 reflections
a = 14.782 (3) Å	θ = 12–18°
b = 5.6774 (11) Å	µ = 5.31 mm^−1
c = 8.7653 (18) Å	T = 293 K
V = 735.6 (3) Å^3	Block, brown
Z = 4	0.15 × 0.14 × 0.14 mm

Data collection

Rigaku Weissenberg IP diffractometer	870 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	θmax = 27.5°, θmin = 2.7°
Graphite monochromator	h = 0→19
scintillation counter scans	k = 0→7
932 measured reflections	l = 0→11
932 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)] = 0.021	H-atom parameters not refined
wR(F^2) = 0.055	w = 1/[σ^2(Fo^2) + (0.0268P)^2 + 0.1878P] where P = (Fo^2 + 2Fc^2)/3
S = 1.00	(Δ/σ)max = 0.001
932 reflections	Δρmax = 1.35 e Å^−3
71 parameters	Δρmin = −1.20 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0084 (5)

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
Mo1	0.032854 (17)	0.2500	0.29379 (3)	0.00992 (12)
Mo2	0.281400 (18)	0.2500	0.99826 (4)	0.01173 (13)
Fe3	0.11699 (3)	0.2500	0.69048 (6)	0.00928 (15)
N1	0.3824 (2)	0.2500	0.5398 (4)	0.0207 (7)
O1	0.05096 (18)	0.2500	0.4921 (3)	0.0160 (6)
O2	−0.03143 (9)	−0.0006 (3)	0.2315 (2)	0.0160 (4)
O3	0.36644 (18)	0.2500	0.8674 (4)	0.0276 (7)
O4	0.17752 (15)	0.2500	0.8922 (3)	0.0188 (6)
O5	0.13360 (17)	0.2500	0.1968 (3)	0.0201 (6)
O6	0.29668 (11)	−0.0097 (4)	1.1099 (2)	0.0191 (4)
H1	0.4304	0.2500	0.6044	0.059 (19)*
H2	0.3286	0.2500	0.5657	0.06 (2)*
H3	0.3904	0.1321	0.4726	0.068 (15)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Mo1	0.00913 (17)	0.01062 (17)	0.01000 (19)	0.000	−0.00015 (9)	0.000
Mo2	0.01073 (18)	0.01119 (18)	0.0133 (2)	0.000	−0.00328 (10)	0.000
Fe3	0.0093 (2)	0.0087 (2)	0.0099 (3)	0.000	−0.00115 (17)	0.000
N1	0.0217 (15)	0.0225 (17)	0.0179 (18)	0.000	0.0016 (14)	0.000
O1	0.0210 (11)	0.0177 (13)	0.0093 (13)	0.000	−0.0019 (9)	0.000
O2	0.0186 (7)	0.0134 (9)	0.0161 (8)	−0.0055 (7)	−0.0029 (6)	0.0005 (9)
O3	0.0192 (12)	0.0387 (17)	0.0248 (16)	0.000	0.0032 (12)	0.000
O4	0.0149 (11)	0.0284 (14)	0.0133 (13)	0.000	−0.0041 (10)	0.000
O5	0.0149 (10)	0.0220 (13)	0.0235 (16)	0.000	0.0055 (10)	0.000
O6	0.0195 (6)	0.0171 (9)	0.0207 (10)	0.0072 (7)	−0.0017 (6)	0.0042 (10)

Geometric parameters (Å, º)

Mo1—O5	1.715 (3)	Fe3—O4	1.981 (3)
Mo1—O1	1.758 (3)	Fe3—O1	1.994 (3)
Mo1—O2	1.7959 (17)	Fe3—O6^ii	1.9972 (18)
Mo1—O2^i	1.7959 (17)	Fe3—O6^iii	1.9972 (18)
Mo2—O3	1.702 (3)	Fe3—O2^iv	2.0178 (17)
Mo2—O6^i	1.784 (2)	Fe3—O2^v	2.0178 (17)
Mo2—O6	1.784 (2)	O2—Fe3^iv	2.0178 (17)
Mo2—O4	1.795 (2)	O6—Fe3^vi	1.9972 (18)
O5—Mo1—O1	110.96 (13)	O1—Fe3—O6^iii	90.26 (8)
O5—Mo1—O2	108.00 (8)	O6^ii—Fe3—O6^iii	86.18 (12)
O1—Mo1—O2	112.39 (8)	O4—Fe3—O2^iv	88.90 (7)
O5—Mo1—O2^i	108.00 (8)	O1—Fe3—O2^iv	89.35 (8)
O1—Mo1—O2^i	112.39 (8)	O6^ii—Fe3—O2^iv	92.34 (7)
O2—Mo1—O2^i	104.79 (11)	O6^iii—Fe3—O2^iv	178.47 (9)
O3—Mo2—O6^i	106.04 (8)	O4—Fe3—O2^v	88.90 (7)
O3—Mo2—O6	106.04 (8)	O1—Fe3—O2^v	89.35 (8)
O6^i—Mo2—O6	111.46 (13)	O6^ii—Fe3—O2^v	178.47 (9)
O3—Mo2—O4	106.42 (13)	O6^iii—Fe3—O2^v	92.34 (7)
O6^i—Mo2—O4	113.11 (7)	O2^iv—Fe3—O2^v	89.13 (10)
O6—Mo2—O4	113.11 (7)	Mo1—O1—Fe3	159.45 (16)
O4—Fe3—O1	177.54 (11)	Mo1—O2—Fe3^iv	141.69 (12)
O4—Fe3—O6^ii	91.54 (8)	Mo2—O4—Fe3	148.04 (15)
O1—Fe3—O6^ii	90.26 (8)	Mo2—O6—Fe3^vi	147.08 (10)
O4—Fe3—O6^iii	91.54 (8)

Symmetry codes: (i) x, −y+1/2, z; (ii) −x+1/2, −y, z−1/2; (iii) −x+1/2, y+1/2, z−1/2; (iv) −x, −y, −z+1; (v) −x, y+1/2, −z+1; (vi) −x+1/2, −y, z+1/2.