The room temperature single-crystal X-ray structure determination of the title compound, PrI3·9H2O, better represented as [Pr(OH2)9]I3, shows unequivocally that it belongs to the structure type preferably adopted by hydrates of the lighter rare earth iodides (La-Ho). The praseodymium cation is coordinated by nine water molecules in the form of a tricapped trigonal prism with the metal atom situated on a site of crystallographic symmetry mm2.
Supporting information
Key indicators
- Single-crystal X-ray study
- T = 298 K
- Mean (r-O) = 0.007 Å
- H-atom completeness 1%
- R factor = 0.050
- wR factor = 0.136
- Data-to-parameter ratio = 24.8
checkCIF/PLATON results
No syntax errors found
Alert level A
PLAT029_ALERT_3_A _diffrn_measured_fraction_theta_full Low ....... 0.92
| Author Response: A missing cusp of data due to datacollection by rotation around
the spindle axis only (IPDS-I). It was impossible to achieve substantial
improvement by remount the crystal as it has to be kept under mother
liquid and
always adopted a preferred orientation.
|
Alert level C
CHEMW03_ALERT_2_C The ratio of given/expected molecular weight as
calculated from the _atom_site* data lies outside
the range 0.99 <> 1.01
From the CIF: _cell_formula_units_Z 2
From the CIF: _chemical_formula_weight 683.75
TEST: Calculate formula weight from _atom_site_*
atom mass num sum
H 1.01 0.00 0.00
O 16.00 9.00 143.99
I 126.90 3.00 380.71
Pr 140.91 1.00 140.91
Calculated formula weight 665.61
CRYSC01_ALERT_1_C The word below has not been recognised as a standard
identifier.
to
REFLT03_ALERT_3_C Reflection count < 95% complete
From the CIF: _diffrn_reflns_theta_max 27.72
From the CIF: _diffrn_reflns_theta_full 27.72
From the CIF: _reflns_number_total 1016
TEST2: Reflns within _diffrn_reflns_theta_max
Count of symmetry unique reflns 1108
Completeness (_total/calc) 91.70%
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings Differ .... ?
PLAT043_ALERT_1_C Check Reported Molecular Weight ................ 683.75
PLAT044_ALERT_1_C Calculated and Reported Dx Differ .............. ?
PLAT068_ALERT_1_C Reported F000 Differs from Calcd (or Missing)... ?
PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for Pr
PLAT431_ALERT_2_C Short Inter HL..A Contact I1 .. O1 .. 3.45 Ang.
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd. # 3
I
Alert level G
FORMU01_ALERT_2_G There is a discrepancy between the atom counts in the
_chemical_formula_sum and the formula from the _atom_site* data.
Atom count from _chemical_formula_sum:H18 I3 O9 Pr1
Atom count from the _atom_site data: I3 O9 Pr1
CELLZ01_ALERT_1_G Difference between formula and atom_site contents detected.
CELLZ01_ALERT_1_G WARNING: H atoms missing from atom site list. Is this intentional?
From the CIF: _cell_formula_units_Z 2
From the CIF: _chemical_formula_sum H18 I3 O9 Pr
TEST: Compare cell contents of formula and atom_site data
atom Z*formula cif sites diff
H 36.00 0.00 36.00
I 6.00 6.00 0.00
O 18.00 18.00 0.00
Pr 2.00 2.00 0.00
1 ALERT level A = In general: serious problem
0 ALERT level B = Potentially serious problem
10 ALERT level C = Check and explain
3 ALERT level G = General alerts; check
7 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
4 ALERT type 2 Indicator that the structure model may be wrong or deficient
2 ALERT type 3 Indicator that the structure quality may be low
1 ALERT type 4 Improvement, methodology, query or suggestion
Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1996); software used to prepare material for publication: SHELXL97.
praseodymium triiodide nonahydrate
top
Crystal data top
PrI3·9H20 | F(000) = 616 |
Mr = 683.75 | Dx = 2.700 Mg m−3 |
Orthorhombic, Pmmn | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ab 2a | Cell parameters from 2000 reflections |
a = 11.720 (2) Å | θ = 1.9–27.7° |
b = 8.0163 (15) Å | µ = 8.42 mm−1 |
c = 8.952 (2) Å | T = 298 K |
V = 841.1 (3) Å3 | Irregular, pale yellow to green |
Z = 2 | 0.30 × 0.10 × 0.05 mm |
Data collection top
Stoe IPDS-I diffractometer | 1016 independent reflections |
Radiation source: fine-focus sealed tube | 870 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.072 |
Detector resolution: not measured pixels mm-1 | θmax = 27.7°, θmin = 1.9° |
φ scans | h = −15→15 |
Absorption correction: numerical X-RED (Stoe & Cie, 2002) and X-SHAPE (Stoe & Cie, 1999) | k = −9→9 |
Tmin = 0.151, Tmax = 0.607 | l = −11→11 |
8456 measured reflections | |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | H-atom parameters not defined |
R[F2 > 2σ(F2)] = 0.050 | w = 1/[σ2(Fo2) + (0.0732P)2 + 3.5369P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.136 | (Δ/σ)max < 0.001 |
S = 1.09 | Δρmax = 1.12 e Å−3 |
1016 reflections | Δρmin = −1.62 e Å−3 |
41 parameters | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.030 (3) |
Primary atom site location: structure-invariant direct methods | |
Special details top
Experimental. A suitable single-crystal was carefully selected under a polarizing microscope
and mounted in a glass capillary. The scattering intensities were collected
with an imaging plate diffractometer (Stoe IPDS-I) equipped with a fine
focus sealed tube X-ray source (Mo Kα, λ = 0.71073 Å) operating at 50 kV
and 30 mA. Intensity data for [Pr(OH2)9]I3 were collected at 298 K by φ
scans in 100 frames (0 < φ < 200° exposure time of 5 min) in the 2Θ range
5–56 °·Structure solution and refinement were carried out using the
program 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 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-factorsbased 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 | x | y | z | Uiso*/Ueq | |
Pr | 0.2500 | 0.2500 | 0.33185 (8) | 0.0438 (3) | |
I1 | 0.00245 (6) | 0.7500 | 0.17176 (8) | 0.0658 (4) | |
I2 | 0.2500 | 0.7500 | −0.29036 (15) | 0.0647 (4) | |
O1 | 0.0570 (6) | 0.2500 | 0.2053 (9) | 0.069 (2) | |
O2 | 0.2500 | 0.0422 (12) | 0.1196 (10) | 0.074 (2) | |
O3 | 0.3788 (4) | 0.4737 (8) | 0.4354 (6) | 0.0663 (16) | |
O4 | 0.2500 | 0.2500 | 0.6158 (12) | 0.064 (3) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Pr | 0.0313 (4) | 0.0669 (6) | 0.0333 (4) | 0.000 | 0.000 | 0.000 |
I1 | 0.0653 (6) | 0.0916 (8) | 0.0405 (5) | 0.000 | −0.0033 (3) | 0.000 |
I2 | 0.0541 (6) | 0.0834 (9) | 0.0567 (7) | 0.000 | 0.000 | 0.000 |
O1 | 0.054 (4) | 0.104 (7) | 0.048 (4) | 0.000 | −0.016 (3) | 0.000 |
O2 | 0.061 (4) | 0.096 (7) | 0.064 (5) | 0.000 | 0.000 | −0.017 (5) |
O3 | 0.053 (3) | 0.088 (5) | 0.057 (3) | −0.016 (2) | 0.002 (2) | −0.004 (3) |
O4 | 0.050 (5) | 0.101 (9) | 0.041 (5) | 0.000 | 0.000 | 0.000 |
Geometric parameters (Å, º) top
Pr—O3 | 2.520 (6) | Pr—O2ii | 2.527 (9) |
Pr—O3i | 2.520 (6) | Pr—O1 | 2.530 (7) |
Pr—O3ii | 2.520 (6) | Pr—O1ii | 2.530 (7) |
Pr—O3iii | 2.520 (6) | Pr—O4 | 2.542 (11) |
Pr—O2 | 2.527 (9) | | |
| | | |
O3—Pr—O3i | 73.6 (3) | O3iii—Pr—O1 | 134.43 (14) |
O3—Pr—O3ii | 136.9 (3) | O2—Pr—O1 | 70.32 (15) |
O3i—Pr—O3ii | 90.7 (3) | O2ii—Pr—O1 | 70.32 (15) |
O3—Pr—O3iii | 90.7 (3) | O3—Pr—O1ii | 68.24 (17) |
O3i—Pr—O3iii | 136.9 (3) | O3i—Pr—O1ii | 134.43 (14) |
O3ii—Pr—O3iii | 73.6 (3) | O3ii—Pr—O1ii | 134.43 (14) |
O3—Pr—O2 | 138.20 (16) | O3iii—Pr—O1ii | 68.24 (17) |
O3i—Pr—O2 | 138.20 (16) | O2—Pr—O1ii | 70.32 (15) |
O3ii—Pr—O2 | 78.9 (2) | O2ii—Pr—O1ii | 70.32 (15) |
O3iii—Pr—O2 | 78.9 (2) | O1—Pr—O1ii | 126.8 (4) |
O3—Pr—O2ii | 78.9 (2) | O3—Pr—O4 | 68.43 (13) |
O3i—Pr—O2ii | 78.9 (2) | O3i—Pr—O4 | 68.43 (13) |
O3ii—Pr—O2ii | 138.20 (16) | O3ii—Pr—O4 | 68.43 (13) |
O3iii—Pr—O2ii | 138.20 (16) | O3iii—Pr—O4 | 68.43 (13) |
O2—Pr—O2ii | 82.5 (4) | O2—Pr—O4 | 138.8 (2) |
O3—Pr—O1 | 134.43 (14) | O2ii—Pr—O4 | 138.8 (2) |
O3i—Pr—O1 | 68.24 (17) | O1—Pr—O4 | 116.60 (19) |
O3ii—Pr—O1 | 68.24 (17) | O1ii—Pr—O4 | 116.60 (19) |
Symmetry codes: (i) −x+1/2, y, z; (ii) −x+1/2, −y+1/2, z; (iii) x, −y+1/2, z. |