Samarium orthosilicate oxy­apatite, Sm₅(SiO₄)₃O

Samarium orthosilicate oxy­apatite, Sm₅(SiO₄)₃O, contains SiO₄^4- tetrahedra [Si-O 1.611 (7)-1.629 (5) Å] and O^2- anions, separated by samarium cations in CN7 [Sm-O 2.2428 (4)-2.641 (7) Å] and CN9 sites [Sm-O 2.428 (5)-2.846 (5) Å]. The full occupancy of the samarium sites implies a mixed valency of four Sm³⁺ and one Sm²⁺ per formula unit.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](Si-O) = 0.008 Å
Some non-H atoms missing
• R factor = 0.031
• wR factor = 0.074
• Data-to-parameter ratio = 17.9

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



FORMU_01  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:O13 Si3 Sm5
          Atom count from the _atom_site data:  O43 Si3 Sm5

CELLZ_01
         From the CIF: _cell_formula_units_Z    2
         From the CIF: _chemical_formula_sum  O13 Si3 Sm5
         TEST: Compare cell contents of formula and atom_site data

         atom    Z*formula  cif sites diff
         O         26.00     86.00  -60.00
         Si         6.00      6.00    0.00
         Sm        10.00     10.00    0.00
          Difference between formula and atom_site contents detected.
          ALERT: Large difference may be due to a
          symmetry error - see SYMMG tests

CHEMW_03
         From the CIF: _cell_formula_units_Z                    2
         From the CIF: _chemical_formula_weight          1044.02
         TEST: Calculate formula weight from _atom_site_*
         atom     mass    num     sum
         O        16.00   43.00  687.96
         Si       28.09    3.00   84.26
         Sm      150.36    5.00  751.80
         Calculated formula weight             1524.01
          ALERT: The ratio of given/expected molecular weight as calculated
          from the _atom_site* data lies outside
          the range 0.90 <> 1.10

---

Computing details

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: ATOMS (Dowty, 1999); software used to prepare material for publication: SHELXTL.

samarium orthosilicate oxyapatite

Crystal data

Sm5(SiO4)3O	Dx = 6.310 Mg m^−3
Mr = 1044.02	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P63/m	Cell parameters from 4159 reflections
Hall symbol: -P 6c	θ = 4.3–32.5°
a = 9.4959 (10) Å	µ = 26.70 mm^−1
c = 7.0361 (7) Å	T = 295 K
V = 549.46 (10) Å^3	Needle, red
Z = 2	0.32 × 0.02 × 0.02 mm
F(000) = 912

Data collection

Bruker Platform/SMART 1000 CCD diffractometer	716 independent reflections
Radiation source: fine-focus sealed tube	650 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.055
ω scans (0.2°)	θmax = 32.6°, θmin = 2.5°
Absorption correction: numerical (SHELXTL; Sheldrick, 1997)	h = −13→14
Tmin = 0.179, Tmax = 0.643	k = −14→14
6710 measured reflections	l = −10→10

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)] = 0.031	w = 1/[σ^2(Fo^2) + (0.0365P)^2 + 5.6399P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.074	(Δ/σ)max < 0.001
S = 1.18	Δρmax = 2.75 e Å^−3
716 reflections	Δρmin = −2.73 e Å^−3
40 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0015 (3)

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
Sm1	0.24063 (5)	0.23148 (5)	0.2500	0.00555 (14)
Sm2	0.3333	0.6667	0.00046 (9)	0.00990 (16)
Si	0.0269 (3)	0.3969 (3)	0.2500	0.0054 (4)
O1	0.0887 (6)	0.3381 (6)	0.0663 (7)	0.0141 (9)
O2	0.1193 (8)	0.5942 (8)	0.2500	0.0148 (13)
O3	0.4817 (8)	0.1682 (8)	0.2500	0.0142 (13)
O4	0.0000	0.0000	0.2500	0.014 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sm1	0.0047 (2)	0.0056 (2)	0.0066 (2)	0.00283 (14)	0.000	0.000
Sm2	0.00999 (19)	0.00999 (19)	0.0097 (3)	0.00500 (10)	0.000	0.000
Si	0.0035 (9)	0.0038 (9)	0.0082 (10)	0.0012 (7)	0.000	0.000
O1	0.016 (2)	0.024 (2)	0.009 (2)	0.015 (2)	−0.0039 (17)	−0.0076 (18)
O2	0.012 (3)	0.007 (3)	0.027 (4)	0.005 (2)	0.000	0.000
O3	0.011 (3)	0.005 (3)	0.021 (4)	−0.001 (2)	0.000	0.000
O4	0.007 (3)	0.007 (3)	0.029 (7)	0.0034 (14)	0.000	0.000

Geometric parameters (Å, º)

Sm1—O4	2.2428 (4)	Sm2—O1	2.846 (5)
Sm1—O1^i	2.383 (5)	Sm2—O1^iii	2.846 (5)
Sm1—O1^ii	2.383 (5)	Sm2—Si^xi	3.2643 (18)
Sm1—O2^iii	2.421 (6)	Sm2—Si	3.2643 (18)
Sm1—O1	2.497 (5)	Sm2—Si^iii	3.2643 (18)
Sm1—O1^iv	2.497 (5)	Si—O3^vi	1.611 (7)
Sm1—O3	2.641 (7)	Si—O2	1.623 (7)
Sm1—Si	3.126 (2)	Si—O1^iv	1.629 (5)
Sm1—Si^v	3.247 (2)	Si—O1	1.629 (5)
Sm1—Sm1^v	3.8847 (8)	Si—Sm1^vi	3.247 (2)
Sm1—Sm1^vi	3.8847 (8)	Si—Sm2^iv	3.2643 (18)
Sm1—Sm2^vii	4.0614 (6)	O1—Sm1^x	2.383 (5)
Sm2—O3^viii	2.428 (5)	O2—Sm1^xi	2.421 (6)
Sm2—O3^ix	2.428 (5)	O2—Sm2^iv	2.508 (5)
Sm2—O3^x	2.428 (5)	O3—Si^v	1.611 (7)
Sm2—O2^xi	2.508 (5)	O3—Sm2^vii	2.428 (5)
Sm2—O2	2.508 (5)	O3—Sm2^ix	2.428 (5)
Sm2—O2^iii	2.508 (5)	O4—Sm1^v	2.2428 (4)
Sm2—O1^xi	2.846 (5)	O4—Sm1^vi	2.2428 (4)
O4—Sm1—O1^i	103.82 (12)	O3^viii—Sm2—O1	89.92 (19)
O4—Sm1—O1^ii	103.82 (12)	O3^ix—Sm2—O1	139.15 (16)
O1^i—Sm1—O1^ii	138.1 (3)	O3^x—Sm2—O1	66.38 (18)
O4—Sm1—O2^iii	152.20 (16)	O2^xi—Sm2—O1	125.99 (15)
O1^i—Sm1—O2^iii	85.01 (12)	O2—Sm2—O1	58.66 (17)
O1^ii—Sm1—O2^iii	85.01 (12)	O2^iii—Sm2—O1	65.84 (17)
O4—Sm1—O1	83.41 (12)	O1^xi—Sm2—O1	117.41 (6)
O1^i—Sm1—O1	137.46 (18)	O3^viii—Sm2—O1^iii	139.15 (16)
O1^ii—Sm1—O1	76.71 (9)	O3^ix—Sm2—O1^iii	66.38 (18)
O2^iii—Sm1—O1	72.91 (18)	O3^x—Sm2—O1^iii	89.92 (19)
O4—Sm1—O1^iv	83.41 (12)	O2^xi—Sm2—O1^iii	65.84 (17)
O1^i—Sm1—O1^iv	76.71 (9)	O2—Sm2—O1^iii	125.99 (15)
O1^ii—Sm1—O1^iv	137.46 (18)	O2^iii—Sm2—O1^iii	58.66 (17)
O2^iii—Sm1—O1^iv	72.91 (18)	O1^xi—Sm2—O1^iii	117.41 (6)
O1—Sm1—O1^iv	62.3 (2)	O1—Sm2—O1^iii	117.41 (5)
O4—Sm1—O3	110.57 (14)	O3^vi—Si—O2	113.1 (4)
O1^i—Sm1—O3	70.52 (13)	O3^vi—Si—O1^iv	110.7 (2)
O1^ii—Sm1—O3	70.52 (13)	O2—Si—O1^iv	108.4 (2)
O2^iii—Sm1—O3	97.2 (2)	O3^vi—Si—O1	110.7 (2)
O1—Sm1—O3	146.53 (12)	O2—Si—O1	108.4 (2)
O1^iv—Sm1—O3	146.53 (12)	O1^iv—Si—O1	105.0 (4)
O3^viii—Sm2—O3^ix	73.13 (17)	Si—O1—Sm1^x	140.8 (3)
O3^viii—Sm2—O3^x	73.13 (17)	Si—O1—Sm1	96.2 (2)
O3^ix—Sm2—O3^x	73.13 (17)	Sm1^x—O1—Sm1	117.46 (19)
O3^viii—Sm2—O2^xi	123.4 (2)	Si—O1—Sm2	89.4 (2)
O3^ix—Sm2—O2^xi	93.63 (16)	Sm1^x—O1—Sm2	101.55 (19)
O3^x—Sm2—O2^xi	155.6 (2)	Sm1—O1—Sm2	102.03 (16)
O3^viii—Sm2—O2	93.63 (16)	Si—O2—Sm1^xi	126.2 (4)
O3^ix—Sm2—O2	155.6 (2)	Si—O2—Sm2^iv	102.3 (2)
O3^x—Sm2—O2	123.4 (2)	Sm1^xi—O2—Sm2^iv	115.09 (19)
O2^xi—Sm2—O2	76.39 (16)	Si—O2—Sm2	102.3 (2)
O3^viii—Sm2—O2^iii	155.6 (2)	Sm1^xi—O2—Sm2	115.09 (19)
O3^ix—Sm2—O2^iii	123.4 (2)	Sm2^iv—O2—Sm2	88.9 (2)
O3^x—Sm2—O2^iii	93.63 (16)	Si^v—O3—Sm2^vii	126.2 (2)
O2^xi—Sm2—O2^iii	76.39 (16)	Si^v—O3—Sm2^ix	126.2 (2)
O2—Sm2—O2^iii	76.39 (16)	Sm2^vii—O3—Sm2^ix	93.1 (2)
O3^viii—Sm2—O1^xi	66.38 (18)	Si^v—O3—Sm1	96.6 (3)
O3^ix—Sm2—O1^xi	89.92 (19)	Sm2^vii—O3—Sm1	106.4 (2)
O3^x—Sm2—O1^xi	139.15 (16)	Sm2^ix—O3—Sm1	106.4 (2)
O2^xi—Sm2—O1^xi	58.66 (17)	Sm1—O4—Sm1^v	120.0
O2—Sm2—O1^xi	65.84 (17)	Sm1—O4—Sm1^vi	120.0
O2^iii—Sm2—O1^xi	125.99 (15)	Sm1^v—O4—Sm1^vi	120.0

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