Bi₃ScMo₂O₁₂: the difference from Bi₃FeMo₂O₁₂

Bi₃ScMo₂O₁₂, tribismuth(III) scandium molybdate(VI), has a framework structure derived from that of scheelite. It is nearly isotypic with Bi₃FeMo₂O₁₂; while in the latter the Fe^III atom is tetrahedrally coordinated by O atoms, the Sc atom in the title compound has a distorted octahedral coordination, and is substituted by Bi to a very minor extent (ca 4%). The change in coordination is achieved predominantly by shifts of two O atoms. The average Sc-O and Mo-O bond lengths are 2.162 and 1.775 Å, respectively. The environments of the two eight-coordinated Bi sites are very similar to those in Bi₃FeMo₂O₁₂. All atoms are on general positions except Sc and one Bi (both of which have site symmetry 2).

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](Mo-O) = 0.003 Å
• R factor = 0.022
• wR factor = 0.052
• Data-to-parameter ratio = 21.3

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



ABSMU_01  Alert C The ratio of given/expected absorption coefficient lies
          outside the range 0.99 <> 1.01
          Calculated value of mu =    55.621
          Value of mu given      =    54.940


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

---

Computing details

Data collection: COLLECT (Nonius, 2002); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO (Otwinowski & Minor, 1997)and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Shape Software, 1999) and ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

tribismuth(III) scandium molybdate(VI)

Crystal data

Bi3.04Sc0.96Mo2O12	F(000) = 1800
Mr = 1055.78	Dx = 6.912 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1881 reflections
a = 16.996 (3) Å	θ = 2.0–32.6°
b = 11.601 (2) Å	µ = 54.94 mm^−1
c = 5.319 (1) Å	T = 293 K
β = 104.67 (3)°	Irregular fragment, yellow
V = 1014.6 (3) Å^3	0.06 × 0.05 × 0.05 mm
Z = 4

Data collection

Nonius KappaCCD diffractometer	1833 independent reflections
Radiation source: fine-focus sealed tube	1777 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.023
ψ and ω scans	θmax = 32.6°, θmin = 3.5°
Absorption correction: multi-scan (HKL SCALEPACK; Otwinowski & Minor, 1997)	h = −25→25
Tmin = 0.052, Tmax = 0.064	k = −17→17
3569 measured reflections	l = −8→7

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)] = 0.022	w = 1/[σ^2(Fo^2) + (0.025P)^2 + 7.1P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.052	(Δ/σ)max = 0.001
S = 1.14	Δρmax = 3.57 e Å^−3
1833 reflections	Δρmin = −3.08 e Å^−3
86 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
1 restraint	Extinction coefficient: 0.00384 (9)

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)
Bi1	0.154483 (9)	0.881574 (12)	0.42921 (3)	0.00517 (7)
Bi2	0.0000	0.662245 (17)	0.2500	0.00605 (7)
Sc	0.0000	0.09325 (10)	0.2500	0.0063 (3)	0.9589 (17)
Bi3	0.0000	0.09325 (10)	0.2500	0.0063 (3)	0.0411 (17)
Mo	0.16858 (2)	0.37156 (3)	0.42735 (7)	0.00543 (8)
O1	0.08237 (17)	0.0238 (3)	0.5871 (6)	0.0061 (5)
O2	0.05005 (19)	0.2055 (3)	0.0279 (6)	0.0084 (6)
O3	0.2165 (2)	0.2877 (3)	0.2330 (6)	0.0111 (6)
O4	0.11628 (19)	0.2825 (3)	0.6196 (6)	0.0093 (6)
O5	0.0948 (2)	0.4556 (3)	0.2225 (7)	0.0144 (6)
O6	0.2466 (2)	0.4544 (3)	0.6306 (6)	0.0122 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Bi1	0.00429 (10)	0.00643 (9)	0.00466 (10)	0.00036 (4)	0.00089 (7)	0.00099 (4)
Bi2	0.00514 (11)	0.00476 (11)	0.00849 (11)	0.000	0.00216 (8)	0.000
Sc	0.0037 (5)	0.0133 (5)	0.0022 (5)	0.000	0.0010 (3)	0.000
Bi3	0.0037 (5)	0.0133 (5)	0.0022 (5)	0.000	0.0010 (3)	0.000
Mo	0.00468 (17)	0.00784 (16)	0.00425 (19)	−0.00094 (12)	0.00201 (14)	−0.00038 (11)
O1	0.0044 (13)	0.0079 (12)	0.0055 (12)	0.0000 (10)	0.0005 (10)	−0.0011 (10)
O2	0.0065 (13)	0.0082 (13)	0.0115 (14)	0.0041 (10)	0.0038 (11)	0.0030 (11)
O3	0.0098 (14)	0.0120 (14)	0.0129 (15)	−0.0007 (12)	0.0055 (12)	−0.0027 (11)
O4	0.0096 (14)	0.0096 (13)	0.0110 (14)	0.0011 (11)	0.0069 (12)	0.0031 (11)
O5	0.0158 (16)	0.0144 (15)	0.0124 (14)	0.0028 (13)	0.0027 (12)	0.0014 (12)
O6	0.0142 (15)	0.0115 (14)	0.0095 (14)	−0.0050 (12)	0.0006 (12)	−0.0008 (11)

Geometric parameters (Å, º)

Bi1—O1^i	2.211 (3)	Bi2—O5^vii	2.955 (4)
Bi1—O2^ii	2.218 (3)	Bi2—O5^ii	2.955 (4)
Bi1—O1^iii	2.335 (3)	Sc—O2^ix	2.079 (3)
Bi1—O4^i	2.492 (3)	Sc—O2	2.079 (3)
Bi1—O3^ii	2.591 (3)	Sc—O1^ix	2.134 (3)
Bi1—O6^iv	2.612 (3)	Sc—O1	2.134 (3)
Bi1—O6^v	2.651 (3)	Sc—O1^x	2.274 (3)
Bi1—O3^vi	2.775 (3)	Sc—O1^xi	2.274 (3)
Bi2—O2^ii	2.151 (3)	Sc—O4	3.259 (3)
Bi2—O2^vii	2.151 (3)	Sc—O4^ix	3.259 (3)
Bi2—O4^i	2.344 (3)	Mo—O5	1.737 (3)
Bi2—O4^viii	2.344 (3)	Mo—O3	1.762 (3)
Bi2—O5^ix	2.913 (4)	Mo—O6	1.767 (3)
Bi2—O5	2.913 (4)	Mo—O4	1.834 (3)
O2^ix—Sc—O2	102.43 (18)	O2—Sc—O1^xi	77.16 (11)
O2^ix—Sc—O1^ix	115.98 (11)	O1^ix—Sc—O1^xi	77.91 (12)
O2—Sc—O1^ix	92.01 (12)	O1—Sc—O1^xi	76.02 (8)
O2^ix—Sc—O1	92.01 (12)	O1^x—Sc—O1^xi	106.66 (16)
O2—Sc—O1	115.98 (11)	O5—Mo—O3	108.03 (16)
O1^ix—Sc—O1	135.63 (17)	O5—Mo—O6	112.91 (16)
O2^ix—Sc—O1^x	77.16 (11)	O3—Mo—O6	105.82 (16)
O2—Sc—O1^x	166.06 (11)	O5—Mo—O4	106.92 (16)
O1^ix—Sc—O1^x	76.02 (8)	O3—Mo—O4	112.13 (14)
O1—Sc—O1^x	77.91 (12)	O6—Mo—O4	111.08 (15)
O2^ix—Sc—O1^xi	166.06 (11)

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