A cubic calcium oxynitrido-silicate, Ca(2.89)Si(2)N(1.76)O(4.24).

The title compound, tricalcium oxynitride silicate, with composition Ca(3-x)Si(2)N(2-2x)O(4+2x) (x ≃ 0.12), is a perovskite-related calcium oxynitrido silicate containing isolated oxynitrido silicate 12-rings. The N atoms are statistically disordered with O atoms (occupancy ratio N:O = 0.88:0.12) and occupy the bridging positions in the 12 ring oxynitrido silicate anion, while the remaining O atoms are located at the terminal positions of the Si(O,N)(4) tetrahedra. The majority of the Ca(2+) cations fill the channels along [100] in the packing of the 12-ring anions. The rest of these cations are located at several positions, with partial occupancy, in channels along the body diagonals.

Related literature

For a closely related silicate, as well as a germanate, see: Fischer & Tillmanns (1984 ▶) and for a more distantly related calcium aluminate, see: Mondal & Jeffery (1975 ▶)

Experimental

Crystal data

Ca2.89Si2N1.76O4.24

M = 264.65

Cubic,

a = 15.0626 (1) Å

V = 3417.45 (4) Å3

Z = 24

Mo Kα radiation

μ = 3.18 mm−1

T = 293 K

0.10 × 0.06 × 0.02 mm

Data collection

Oxford Diffraction XcaliburIII with Sapphire-3 CCD diffractometer

Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2008 ▶) T min = 0.67, T max = 0.94

30793 measured reflections

1982 independent reflections

1779 reflections with I > 2s(I)

R int = 0.027

Refinement

R[F 2 > 2σ(F 2)] = 0.032

wR(F 2) = 0.069

S = 1.22

1982 reflections

113 parameters

Δρmax = 0.87 e Å−3

Δρmin = −0.76 e Å−3

Data collection: CrysAlis CCD (Oxford Diffraction, 2008 ▶); cell refinement: CrysAlis RED (Oxford Diffraction, 2008 ▶); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 2001 ▶); software used to prepare material for publication: PLATON (Spek, 2009 ▶) and SHELXL97.

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811042607/fj2455sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811042607/fj2455Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Ca2.89Si2N1.76O4.24	Dx = 3.087 Mg m−3
Mr = 264.65	Mo Kα radiation, λ = 0.71073 Å
Cubic, Pa3	Cell parameters from 19622 reflections
Hall symbol: -P 2ac 2ab 3	θ = 3.8–32.2°
a = 15.0626 (1) Å	µ = 3.18 mm−1
V = 3417.45 (4) Å3	T = 293 K
Z = 24	Block, colourless
F(000) = 3158	0.10 × 0.06 × 0.02 mm

Oxford Diffraction XcaliburIII with Sapphire-3 CCD diffractometer	1982 independent reflections
Radiation source: fine-focus sealed tube	1779 reflections with I > 2s(I)
graphite	Rint = 0.027
Detector resolution: 16.5467 pixels mm-1	θmax = 32.3°, θmin = 3.8°
ω scans at different φ	h = −22→18
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2008)	k = −18→21
Tmin = 0.67, Tmax = 0.94	l = −22→21
30793 measured reflections

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.032	w = 1/[σ2(Fo2) + (0.026P)2 + 5.7834P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.069	(Δ/σ)max = 0.001
S = 1.22	Δρmax = 0.87 e Å−3
1982 reflections	Δρmin = −0.76 e Å−3
113 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraints	Extinction coefficient: 0.00048 (5)

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.

	x	y	z	Uiso*/Ueq	Occ. (<1)
Si1	0.00530 (3)	0.27221 (3)	0.76315 (3)	0.00633 (9)
Si2	0.01658 (3)	0.24358 (3)	0.98439 (3)	0.00567 (9)
N1	0.01861 (12)	0.37791 (11)	0.72676 (13)	0.0176 (3)	0.88
O1	0.01861 (12)	0.37791 (11)	0.72676 (13)	0.0176 (3)	0.12
N2	0.00891 (13)	0.26556 (13)	0.87435 (11)	0.0193 (4)	0.88
O2	0.00891 (13)	0.26556 (13)	0.87435 (11)	0.0193 (4)	0.12
O3	0.09048 (10)	0.21494 (9)	0.72534 (9)	0.0131 (3)
O4	−0.09065 (10)	0.23612 (10)	0.72964 (10)	0.0160 (3)
O5	−0.01845 (10)	0.33802 (10)	1.02719 (10)	0.0147 (3)
O6	−0.04423 (10)	0.15759 (10)	1.01040 (10)	0.0153 (3)
Ca1	−0.12893 (2)	0.37107 (2)	1.12893 (2)	0.01028 (12)
Ca2	−0.11371 (3)	0.38333 (3)	0.90382 (3)	0.01162 (8)
Ca3	0.13964 (3)	0.13071 (3)	0.85405 (3)	0.01601 (9)
Ca4	0.24330 (14)	0.25670 (14)	0.74330 (14)	0.0094 (6)*	0.1715 (6)
Ca5	0.1757 (2)	0.3243 (2)	0.6757 (2)	0.0094 (2)*	0.140 (2)
Ca6	0.15523 (5)	0.34477 (5)	0.65523 (5)	0.0094 (2)*	0.670 (3)
Ca7	0.1254 (9)	0.3746 (9)	0.6254 (9)	0.0094 (2)*	0.043 (3)
Ca8	0.1031 (7)	0.3969 (7)	0.6031 (7)	0.0094 (2)*	0.076 (2)
Ca9	0.0819 (5)	0.4181 (5)	0.5819 (5)	0.0094 (2)*	0.086 (3)
Ca10	0.0572 (3)	0.4428 (3)	0.5572 (3)	0.0094 (2)*	0.099 (2)
Ca11	0.0166 (4)	0.4834 (4)	0.5166 (4)	0.0094 (2)*	0.095 (3)
Ca12	0.0000	0.5000	0.5000	0.0094 (2)*	0.603 (6)

	U11	U22	U33	U12	U13	U23
Si1	0.0077 (2)	0.0061 (2)	0.0052 (2)	−0.00013 (16)	−0.00028 (15)	−0.00047 (15)
Si2	0.00564 (19)	0.0064 (2)	0.0049 (2)	0.00030 (16)	0.00068 (15)	−0.00020 (16)
N1	0.0206 (8)	0.0063 (7)	0.0260 (9)	0.0011 (6)	0.0043 (7)	0.0004 (6)
O1	0.0206 (8)	0.0063 (7)	0.0260 (9)	0.0011 (6)	0.0043 (7)	0.0004 (6)
N2	0.0240 (9)	0.0274 (9)	0.0066 (7)	−0.0007 (7)	0.0010 (6)	−0.0004 (6)
O2	0.0240 (9)	0.0274 (9)	0.0066 (7)	−0.0007 (7)	0.0010 (6)	−0.0004 (6)
O3	0.0149 (6)	0.0105 (6)	0.0140 (6)	0.0035 (5)	0.0042 (5)	−0.0008 (5)
O4	0.0150 (6)	0.0162 (7)	0.0169 (7)	−0.0055 (5)	−0.0065 (5)	0.0014 (5)
O5	0.0174 (7)	0.0124 (6)	0.0144 (6)	0.0057 (5)	−0.0035 (5)	−0.0062 (5)
O6	0.0157 (7)	0.0132 (6)	0.0170 (7)	−0.0063 (5)	0.0040 (5)	0.0008 (5)
Ca1	0.01028 (12)	0.01028 (12)	0.01028 (12)	−0.00048 (12)	0.00048 (12)	0.00048 (12)
Ca2	0.01262 (17)	0.00917 (16)	0.01306 (17)	0.00006 (12)	−0.00140 (13)	0.00004 (12)
Ca3	0.01781 (19)	0.01586 (19)	0.01435 (18)	0.00563 (14)	−0.00307 (14)	−0.00105 (14)

Si1—O4	1.6245 (15)	Si2—O6	1.6341 (15)
Si1—O3	1.6476 (14)	Si2—O5	1.6485 (15)
Si1—N2	1.6788 (18)	Si2—N1i	1.6899 (17)
Si1—N1	1.6958 (17)	Si2—N2	1.6942 (18)
O4—Si1—O3	114.22 (8)	O6—Si2—N1i	109.58 (9)
O4—Si1—N2	108.60 (9)	O5—Si2—N1i	108.13 (9)
O3—Si1—N2	106.76 (9)	O6—Si2—N2	110.56 (9)
O4—Si1—N1	108.59 (9)	O5—Si2—N2	101.08 (9)
O3—Si1—N1	106.72 (8)	O1i—Si2—N2	113.07 (9)
N2—Si1—N1	112.00 (10)	N1i—Si2—N2	113.07 (9)
O6—Si2—O5	114.26 (8)	Si2ii—N1—Si1	142.98 (12)
O6—Si2—O1i	109.58 (9)	Si1—N2—Si2	171.87 (14)
O5—Si2—O1i	108.13 (9)
N2—Si1—N1—Si2ii	−46.7 (2)

Table 1

Selected bond lengths (Å)

Si1—O4	1.6245 (15)
Si1—O3	1.6476 (14)
Si1—N2/O2	1.6788 (18)
Si1—N1/O1	1.6958 (17)
Si2—O6	1.6341 (15)
Si2—O5	1.6485 (15)
Si2—N1/O1i	1.6899 (17)
Si2—N2/O2	1.6942 (18)

Symmetry code: (i) .