The cluster compound PrMo_7.6O₁₄

Praseodymium molybdenum oxide, PrMo_7.6O₁₄, is isostructural with LaMo_7.7O₁₄ and NdMo_7.7O₁₄. Their crystal structures derive from the NdMo₈O₁₄ type, which contains cis-edge-sharing bi-face-capped octahedral Mo₈ clusters. Because of the non-stoichiometry on the capping Mo sites and the absence of satellite reflections, Mo₆, Mo₇ and Mo₈ clusters are believed to co-exist randomly.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](Mo-Mo) = 0.001 Å
• R factor = 0.041
• wR factor = 0.093
• Data-to-parameter ratio = 23.5

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



ABSTM_02  When printed, the submitted absorption T values will be replaced
          by the scaled T values. Since the ratio of scaled T's is
          identical to the ratio of reported T values, the scaling does
          not imply a change to the absorption corrections used in the
          study.
          Ratio of Tmax expected/reported      1.060
          Tmax scaled      0.538 Tmin scaled      0.427

REFLT_03
         From the CIF: _diffrn_reflns_theta_max           37.90
         From the CIF: _reflns_number_total               2540
         Count of symmetry unique reflns         1435
         Completeness (_total/calc)            177.00%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured      1105
         Fraction of Friedel pairs measured     0.770
         Are heavy atom types Z>Si present          yes
          Please check that the estimate of the number of Friedel pairs is
          correct. If it is not, please give the correct count in the
          _publ_section_exptl_refinement section of the submitted CIF.

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Computing details

Data collection: COLLECT (Nonius, 1998); cell refinement: COLLECT (Nonius, 1998); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Bergerhoff, 1996); software used to prepare material for publication: SHELXL97.

(I)

Crystal data

PrMo7.6O14	F(000) = 1964
Mr = 1095.97	Dx = 7.121 Mg m^−3
Orthorhombic, Aba2	Mo Kα radiation, λ = 0.71070 Å
Hall symbol: A 2 -2ac	Cell parameters from 25995 reflections
a = 9.1611 (4) Å	θ = 1.0–37.8°
b = 9.9709 (9) Å	µ = 13.78 mm^−1
c = 11.1916 (8) Å	T = 293 K
V = 1022.29 (13) Å^3	Irregular, black
Z = 4	0.06 × 0.05 × 0.05 mm

Data collection

Nonius KappaCCD diffractometer	2540 independent reflections
Radiation source: fine-focus sealed tube	2249 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.056
φ scans (κ = 0) + additional ω scans	θmax = 37.9°, θmin = 3.5°
Absorption correction: multi-scan (Blessing, 1995)	h = −15→15
Tmin = 0.403, Tmax = 0.508	k = −17→16
11744 measured reflections	l = −19→16

Refinement

Refinement on F^2	w = 1/[σ^2(Fo^2) + (0.0333P)^2 + 22.8476P] where P = (Fo^2 + 2Fc^2)/3
Least-squares matrix: full	(Δ/σ)max = 0.001
R[F^2 > 2σ(F^2)] = 0.041	Δρmax = 3.97 e Å^−3
wR(F^2) = 0.093	Δρmin = −2.37 e Å^−3
S = 1.10	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
2540 reflections	Extinction coefficient: 0.00076 (8)
108 parameters	Absolute structure: Flack (1983), 1118 Friedel pairs
1 restraint	Absolute structure parameter: −0.01 (3)
Primary atom site location: isomorphous structure methods

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)
Pr	0.0000	0.0000	−0.49898 (8)	0.01351 (12)
Mo1	0.12171 (6)	−0.07440 (6)	−0.83846 (5)	0.00714 (12)
Mo2	0.11808 (6)	0.16064 (6)	0.04122 (6)	0.00751 (11)
Mo3	0.12480 (6)	−0.08226 (5)	−0.08178 (5)	0.00711 (12)
Mo4	0.12393 (8)	0.66281 (8)	−0.69447 (7)	0.0093 (2)	0.811 (4)
O1	0.2426 (7)	0.3322 (5)	−0.2052 (5)	0.0076 (9)
O2	0.2468 (7)	0.0841 (5)	−0.3338 (6)	0.0105 (9)
O3	0.0155 (6)	0.2513 (6)	−0.3355 (5)	0.0091 (9)
O4	0.2319 (5)	0.3462 (5)	−0.9577 (6)	0.0099 (9)
O5	0.2674 (6)	0.0812 (5)	−0.0774 (6)	0.0122 (10)
O6	−0.0075 (6)	0.2605 (6)	−0.0790 (6)	0.0154 (11)
O7	0.0000	0.0000	−0.7139 (7)	0.0083 (13)
O8	0.0000	0.0000	−0.2230 (9)	0.0191 (18)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pr	0.0119 (2)	0.0128 (2)	0.0158 (2)	0.00103 (19)	0.000	0.000
Mo1	0.0056 (2)	0.0073 (2)	0.0084 (3)	0.00063 (16)	−0.0005 (2)	0.00000 (19)
Mo2	0.0059 (2)	0.0070 (2)	0.0097 (2)	0.00050 (16)	−0.0011 (2)	−0.0011 (2)
Mo3	0.0056 (2)	0.0082 (2)	0.0076 (3)	0.00108 (16)	−0.00012 (19)	0.0004 (2)
Mo4	0.0080 (3)	0.0083 (3)	0.0117 (4)	0.0021 (2)	−0.0027 (2)	−0.0031 (3)
O1	0.0080 (18)	0.0057 (18)	0.009 (2)	0.0008 (19)	−0.0038 (16)	0.0004 (17)
O2	0.0114 (19)	0.0103 (19)	0.010 (2)	0.002 (2)	0.003 (2)	−0.001 (2)
O3	0.008 (2)	0.0089 (19)	0.011 (2)	−0.0015 (15)	−0.0004 (18)	0.0037 (19)
O4	0.0071 (18)	0.009 (2)	0.014 (2)	−0.0008 (15)	0.002 (2)	0.002 (2)
O5	0.015 (2)	0.010 (2)	0.011 (2)	−0.0021 (17)	0.006 (2)	−0.002 (2)
O6	0.013 (2)	0.016 (2)	0.017 (3)	−0.0044 (19)	−0.008 (3)	0.007 (2)
O7	0.006 (3)	0.005 (3)	0.014 (4)	0.002 (3)	0.000	0.000
O8	0.018 (4)	0.026 (4)	0.013 (4)	0.004 (4)	0.000	0.000

Geometric parameters (Å, º)

Pr—O7	2.405 (8)	Mo2—O4^xiii	2.124 (5)
Pr—O5^i	2.443 (6)	Mo2—Mo4^v	2.6384 (11)
Pr—O5^ii	2.443 (6)	Mo2—Mo1^xiii	2.7031 (8)
Pr—O6^iii	2.552 (6)	Mo2—Mo1^xiv	2.7163 (8)
Pr—O6^iv	2.552 (6)	Mo2—Mo3^vii	2.7306 (8)
Pr—O4^v	2.661 (5)	Mo2—Mo3	2.7864 (8)
Pr—O4^vi	2.661 (5)	Mo2—Pr^xv	3.5808 (6)
Pr—O2	3.038 (7)	Mo2—Pr^xvi	3.8742 (6)
Pr—O2^vii	3.038 (7)	Mo3—O1^viii	2.027 (6)
Pr—O8	3.088 (10)	Mo3—O4^xvii	2.040 (6)
Pr—O3	3.106 (6)	Mo3—O6^vii	2.077 (6)
Pr—O3^vii	3.106 (6)	Mo3—O5	2.090 (5)
Pr—Mo2^iii	3.5808 (6)	Mo3—O8	2.116 (7)
Pr—Mo2^iv	3.5808 (6)	Mo3—Mo1^xiii	2.7244 (9)
Pr—Mo3^i	3.6532 (6)	Mo3—Mo4^vi	2.7254 (11)
Pr—Mo3^ii	3.6532 (6)	Mo3—Mo2^vii	2.7306 (8)
Pr—Mo2^i	3.8742 (6)	Mo3—Mo4^v	2.7499 (10)
Mo1—O7	1.933 (6)	Mo3—Mo3^vii	2.8141 (11)
Mo1—O2^i	1.988 (6)	Mo3—Pr^xvi	3.6532 (6)
Mo1—O3^iv	1.992 (6)	Mo3—Mo4^xviii	3.6539 (10)
Mo1—O4^viii	2.051 (6)	Mo3—Mo1^xii	3.6948 (8)
Mo1—O1^iv	2.078 (6)	Mo4—O8^xix	2.0066 (18)
Mo1—Mo1^vii	2.6784 (12)	Mo4—O1^xix	2.012 (5)
Mo1—Mo2^ix	2.7031 (8)	Mo4—O6^xix	2.017 (7)
Mo1—Mo2^x	2.7163 (8)	Mo4—O5^xix	2.026 (7)
Mo1—Mo3^ix	2.7244 (9)	Mo4—O3^xix	2.063 (6)
Mo1—Mo4^xi	3.0761 (10)	Mo4—O2^xix	2.077 (6)
Mo1—Mo4^viii	3.6907 (10)	Mo4—Mo2^xix	2.6384 (11)
Mo1—Mo3^i	3.6948 (8)	Mo4—Mo3^iii	2.7254 (11)
Mo2—O2^xii	2.018 (7)	Mo4—Mo3^xix	2.7499 (10)
Mo2—O6	2.031 (6)	Mo4—Mo1^xx	3.0761 (10)
Mo2—O3^vi	2.043 (6)	Mo4—Mo3^xxi	3.6539 (10)
Mo2—O5	2.064 (6)	Mo4—Mo1^xxii	3.6907 (10)
O7—Mo1—O2^i	91.5 (2)	O1^viii—Mo3—O5	88.2 (2)
O7—Mo1—O3^iv	92.36 (17)	O4^xvii—Mo3—O5	81.7 (2)
O2^i—Mo1—O3^iv	171.6 (2)	O6^vii—Mo3—O5	172.2 (2)
O7—Mo1—O4^viii	174.0 (2)	O1^viii—Mo3—O8	88.7 (2)
O2^i—Mo1—O4^viii	85.9 (2)	O4^xvii—Mo3—O8	172.6 (2)
O3^iv—Mo1—O4^viii	89.6 (2)	O6^vii—Mo3—O8	93.62 (19)
O7—Mo1—O1^iv	87.8 (2)	O5—Mo3—O8	93.02 (19)
O2^i—Mo1—O1^iv	90.8 (3)	O8^xix—Mo4—O1^xix	167.2 (3)
O3^iv—Mo1—O1^iv	81.8 (2)	O8^xix—Mo4—O6^xix	98.9 (2)
O4^viii—Mo1—O1^iv	86.9 (2)	O1^xix—Mo4—O6^xix	87.4 (2)
O2^xii—Mo2—O6	172.8 (2)	O8^xix—Mo4—O5^xix	98.3 (2)
O2^xii—Mo2—O3^vi	93.5 (3)	O1^xix—Mo4—O5^xix	91.4 (2)
O6—Mo2—O3^vi	84.1 (2)	O6^xix—Mo4—O5^xix	99.6 (2)
O2^xii—Mo2—O5	83.9 (3)	O8^xix—Mo4—O3^xix	87.2 (3)
O6—Mo2—O5	97.9 (3)	O1^xix—Mo4—O3^xix	81.7 (2)
O3^vi—Mo2—O5	175.1 (2)	O6^xix—Mo4—O3^xix	89.8 (2)
O2^xii—Mo2—O4^xiii	91.4 (2)	O5^xix—Mo4—O3^xix	168.1 (2)
O6—Mo2—O4^xiii	81.7 (2)	O8^xix—Mo4—O2^xix	83.2 (3)
O3^vi—Mo2—O4^xiii	85.2 (2)	O1^xix—Mo4—O2^xix	88.8 (2)
O5—Mo2—O4^xiii	90.7 (2)	O6^xix—Mo4—O2^xix	170.7 (2)
O1^viii—Mo3—O4^xvii	86.1 (2)	O5^xix—Mo4—O2^xix	89.0 (3)
O1^viii—Mo3—O6^vii	87.7 (2)	O3^xix—Mo4—O2^xix	81.3 (2)
O4^xvii—Mo3—O6^vii	91.4 (2)

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