Praseodymium dodeca­iodo-ferro-octa­hedro-hexa­praseodymium, Pr₇I₁₂Fe

Heptapraseodymium iron dodeca­iodide or praseodymium dodeca­iodo-ferro-octa­hedro-hexa­praseodymium, Pr₇I₁₂Fe (= Pr{Pr₆Fe}I₁₂), was obtained as black single crystals during investigations of the Pr-Fe-I system. It crystallizes with the Sc₇Cl₁₂N-type of structure. According to the formula Pr1{Pr2₆Fe}I1₆ⁱI2₆^i-a, it contains `isolated' {Pr2₆Fe} clusters, edge-capped by 12 I^- ligands, with Pr1 filling the otherwise empty octa­hedral holes between the I^- ions. Both Pr-Pr [3.9119 (8) and 3.9150 (8) Å] and Pr-Fe distances [2.7672 (5) Å] within the {Pr2₆Fe} cluster are in good agreement with those of similar compounds, as are the Pr-I distances. One of the Pr atoms and both I atoms occupy sites with symmetry 1 (Wyckhoff position 18f). The second Pr atom (3a) and the Fe atom (3b) are situated in sites with symmetry .

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](r-Fe) = 0.001 Å
• R factor = 0.046
• wR factor = 0.099
• Data-to-parameter ratio = 55.4

checkCIF/PLATON results

No syntax errors found



Alert level A
DIFF019_ALERT_1_A  _diffrn_standards_number is missing
            Number of standards used in measurement.
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 B
DIFMN02_ALERT_2_B  The minimum difference density is < -0.1*ZMAX*1.00
            _refine_diff_density_min given =     -5.982
            Test value =     -5.900
PLAT098_ALERT_2_B Minimum (Negative) Residual Density ............      -5.98 e/A   3

Alert level C
DIFMN03_ALERT_1_C  The minimum difference density is < -0.1*ZMAX*0.75
            The relevant atom site should be identified.
PLAT199_ALERT_1_C Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_C Check the Reported _diffrn_ambient_temperature .        293 K

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

   6 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 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: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 2001); software used to prepare material for publication: SHELXL97.

Heptapraseodymium iron dodecaiodide

Crystal data

FeI12Pr7	Dx = 5.461 Mg m^−3
Mr = 2565.02	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3	Cell parameters from 13127 reflections
Hall symbol: -R 3	θ = 2.4–32.2°
a = 15.8296 (10) Å	µ = 23.02 mm^−1
c = 10.7833 (6) Å	T = 293 K
V = 2340.0 (2) Å^3	Rhomb, black
Z = 3	0.25 × 0.15 × 0.05 mm
F(000) = 3225

Data collection

Stoe IPDS-II diffractometer	1829 independent reflections
Radiation source: fine-focus sealed tube	1593 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.065
ω and φ scans	θmax = 32.2°, θmin = 2.4°
Absorption correction: numerical [X-SHAPE (Stoe & Cie, 1999) and X-RED (Stoe & Cie, 2001)]	h = −23→23
Tmin = 0.027, Tmax = 0.324	k = −23→23
13579 measured reflections	l = −15→16

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)] = 0.046	w = 1/[σ^2(Fo^2) + (0.0261P)^2 + 153.022P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.099	(Δ/σ)max = 0.001
S = 1.04	Δρmax = 3.54 e Å^−3
1829 reflections	Δρmin = −5.98 e Å^−3
33 parameters	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.00067 (3)

Special details

Experimental. A suitable single-crystal was carefully selected under a polarizing microscope and mounted in a glass capillary. The scattering intensities were collected on an imaging plate diffractometer (IPDS II, Stoe & Cie) equipped with a fine focus sealed tube X-ray source (Mo Kα, λ = 0.71073 Å) operating at 50 kV and 40 mA. Intensity data for the title compound were collected at room temperature by ω-scans in 254 frames (0 < ω < 180°; φ = O°, 0 < ω < 74°; φ = 90°, Δω = 1°, exposure time of 5 min) in the 2 Θ range 2.9 to 64.8°. Structure solution and refinement were carried out using the programs SIR92 (Altomare et al., 1993) and SHELXL97 (Sheldrick, 1997). A numerical absorption correction (X-RED (Stoe & Cie, 2001) was applied after optimization of the crystal shape (X-SHAPE (Stoe & Cie, 1999)). The last cycles of refinement included atomic positions and anisotropic parameters for all atoms. The final difference maps were free of any chemically significant features. The refinement was based on F² for ALL reflections.

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
Pr2	0.44849 (3)	0.62205 (3)	0.01862 (4)	0.02645 (14)
Pr1	0.3333	0.6667	0.6667	0.0507 (4)
I1	0.41239 (4)	0.43177 (4)	0.16421 (5)	0.03380 (16)
I2	0.52062 (4)	0.80126 (4)	0.82596 (5)	0.02966 (15)
Fe	0.3333	0.6667	0.1667	0.0180 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pr2	0.0257 (2)	0.0217 (2)	0.0285 (2)	0.00922 (15)	−0.00511 (14)	0.00157 (14)
Pr1	0.0282 (4)	0.0282 (4)	0.0957 (12)	0.01410 (18)	0.000	0.000
I1	0.0424 (3)	0.0327 (3)	0.0369 (3)	0.0267 (2)	0.0131 (2)	0.0087 (2)
I2	0.0314 (3)	0.0299 (3)	0.0285 (3)	0.0159 (2)	0.00662 (18)	0.00437 (17)
Fe	0.0170 (6)	0.0170 (6)	0.0200 (10)	0.0085 (3)	0.000	0.000

Geometric parameters (Å, º)

Pr2—Fe	2.7672 (5)	Pr1—I2	3.1564 (6)
Pr2—I1	3.1847 (7)	Pr1—I2^vi	3.1564 (6)
Pr2—I1^i	3.1950 (7)	Pr1—I2^x	3.1564 (6)
Pr2—I2^ii	3.2292 (7)	I1—Pr2^v	3.1951 (7)
Pr2—I2^iii	3.2367 (7)	I1—Pr2^iv	3.3674 (7)
Pr2—I1^iv	3.3674 (7)	I2—Pr2^xi	3.2292 (7)
Pr2—Pr2^v	3.9119 (8)	I2—Pr2^xii	3.2367 (7)
Pr2—Pr2^i	3.9119 (8)	Fe—Pr2^v	2.7672 (5)
Pr2—Pr2^vi	3.9150 (8)	Fe—Pr2^vi	2.7672 (5)
Pr2—Pr2^vii	3.9150 (8)	Fe—Pr2^vii	2.7672 (5)
Pr1—I2^viii	3.1564 (6)	Fe—Pr2^i	2.7672 (5)
Pr1—I2^vii	3.1564 (6)	Fe—Pr2^xiii	2.7673 (5)
Pr1—I2^ix	3.1564 (6)
Fe—Pr2—I1	97.320 (16)	I1^iv—Pr2—Pr2^vii	134.585 (15)
Fe—Pr2—I1^i	97.080 (16)	Pr2^v—Pr2—Pr2^vii	90.0
I1—Pr2—I1^i	89.147 (11)	Pr2^i—Pr2—Pr2^vii	59.973 (7)
Fe—Pr2—I2^ii	97.798 (16)	Pr2^vi—Pr2—Pr2^vii	60.0
I1—Pr2—I2^ii	164.88 (2)	I2^viii—Pr1—I2^vii	180.0
I1^i—Pr2—I2^ii	88.923 (18)	I2^viii—Pr1—I2^ix	93.198 (13)
Fe—Pr2—I2^iii	97.624 (16)	I2^vii—Pr1—I2^ix	86.802 (13)
I1—Pr2—I2^iii	87.705 (19)	I2^viii—Pr1—I2	86.803 (13)
I1^i—Pr2—I2^iii	165.24 (2)	I2^vii—Pr1—I2	93.197 (13)
I2^ii—Pr2—I2^iii	90.36 (2)	I2^ix—Pr1—I2	180.0
Fe—Pr2—I1^iv	179.395 (18)	I2^viii—Pr1—I2^vi	86.803 (13)
I1—Pr2—I1^iv	83.112 (17)	I2^vii—Pr1—I2^vi	93.197 (13)
I1^i—Pr2—I1^iv	83.344 (18)	I2^ix—Pr1—I2^vi	86.803 (13)
I2^ii—Pr2—I1^iv	81.771 (17)	I2—Pr1—I2^vi	93.197 (13)
I2^iii—Pr2—I1^iv	81.964 (18)	I2^viii—Pr1—I2^x	93.198 (13)
Fe—Pr2—Pr2^v	45.022 (6)	I2^vii—Pr1—I2^x	86.802 (13)
I1—Pr2—Pr2^v	52.302 (15)	I2^ix—Pr1—I2^x	93.197 (13)
I1^i—Pr2—Pr2^v	94.597 (18)	I2—Pr1—I2^x	86.803 (13)
I2^ii—Pr2—Pr2^v	142.815 (14)	I2^vi—Pr1—I2^x	180.0
I2^iii—Pr2—Pr2^v	94.865 (14)	Pr2—I1—Pr2^v	75.64 (2)
I1^iv—Pr2—Pr2^v	135.413 (15)	Pr2—I1—Pr2^iv	96.888 (17)
Fe—Pr2—Pr2^i	45.022 (6)	Pr2^v—I1—Pr2^iv	172.53 (2)
I1—Pr2—Pr2^i	95.633 (19)	Pr1—I2—Pr2^xi	87.532 (16)
I1^i—Pr2—Pr2^i	52.061 (15)	Pr1—I2—Pr2^xii	87.402 (16)
I2^ii—Pr2—Pr2^i	94.987 (14)	Pr2^xi—I2—Pr2^xii	74.53 (2)
I2^iii—Pr2—Pr2^i	142.641 (15)	Pr2^v—Fe—Pr2^vi	89.955 (12)
I1^iv—Pr2—Pr2^i	135.395 (16)	Pr2^v—Fe—Pr2^vii	180.0
Pr2^v—Pr2—Pr2^i	60.051 (14)	Pr2^vi—Fe—Pr2^vii	90.045 (12)
Fe—Pr2—Pr2^vi	44.977 (6)	Pr2^v—Fe—Pr2^i	90.046 (12)
I1—Pr2—Pr2^vi	94.706 (18)	Pr2^vi—Fe—Pr2^i	180.0
I1^i—Pr2—Pr2^vi	142.053 (14)	Pr2^vii—Fe—Pr2^i	89.954 (12)
I2^ii—Pr2—Pr2^vi	96.025 (13)	Pr2^v—Fe—Pr2	89.956 (12)
I2^iii—Pr2—Pr2^vi	52.650 (15)	Pr2^vi—Fe—Pr2	90.045 (12)
I1^iv—Pr2—Pr2^vi	134.602 (16)	Pr2^vii—Fe—Pr2	90.045 (12)
Pr2^v—Pr2—Pr2^vi	59.973 (7)	Pr2^i—Fe—Pr2	89.956 (12)
Pr2^i—Pr2—Pr2^vi	90.0	Pr2^v—Fe—Pr2^xiii	90.044 (12)
Fe—Pr2—Pr2^vii	44.977 (6)	Pr2^vi—Fe—Pr2^xiii	89.955 (12)
I1—Pr2—Pr2^vii	142.294 (15)	Pr2^vii—Fe—Pr2^xiii	89.954 (12)
I1^i—Pr2—Pr2^vii	95.402 (18)	Pr2^i—Fe—Pr2^xiii	90.044 (12)
I2^ii—Pr2—Pr2^vii	52.824 (14)	Pr2—Fe—Pr2^xiii	179.999 (13)
I2^iii—Pr2—Pr2^vii	95.900 (13)

Symmetry codes: (i) x−y+2/3, x+1/3, −z+1/3; (ii) x, y, z−1; (iii) −x+y, −x+1, z−1; (iv) −x+1, −y+1, −z; (v) y−1/3, −x+y+1/3, −z+1/3; (vi) −x+y, −x+1, z; (vii) −y+1, x−y+1, z; (viii) y−1/3, −x+y+1/3, −z+4/3; (ix) −x+2/3, −y+4/3, −z+4/3; (x) x−y+2/3, x+1/3, −z+4/3; (xi) x, y, z+1; (xii) −y+1, x−y+1, z+1; (xiii) −x+2/3, −y+4/3, −z+1/3.