Redetermination of the low-temperature polymorph of Li(2)MnSiO(4) from single-crystal X-ray data.

Crystals of dilithium manganese(II) silicate were grown under high-temperature hydro-thermal conditions in the system LiOH-MnO(2)-SiO(2). The title compound crystallizes in the β(II)-Li(3)PO(4) structure type. The coordination polyhedra of all cations are slightly distorted tetra-hedra (m symmetry for MnO(4) and SiO(4)), which are linked by corner-sharing to each other. The vertices of the tetra-hedra point to the same direction perpendicular to the distorted hexa-gonal close-packed (hcp) array of O atoms within which half of the tetra-hedral voids are occupied by cations. In comparison with the previous refinement from powder X-ray data [Dominko et al. (2006 ▶). Electrochem. Commun.8, 217-222], the present reinvestigation from single-crystal X-ray data allows a more precise determination of the distribution of the Li(+) and Mn(2+) cations, giving a perfectly site-ordered structure model for both Li(+) and Mn(2+).

Related literature

For background to structural studies of Li2 MSiO4 (M = Mn, Fe, Co) compounds, see: Islam et al. (2011 ▶); Santamaría-Pérez et al. (2012 ▶); Setoguchi (1988 ▶); Yamaguchi et al. (1979 ▶). Polymorphism of Li2MnSiO4 was reported by Arroyo-de Dompablo et al. (2006 ▶, 2008 ▶); Belharouak et al. (2009 ▶); Dominko et al. (2006 ▶); Kokalj et al. (2007 ▶); Politaev et al. (2007 ▶); Wu et al. (2009 ▶); Zhong et al. (2010 ▶). For notation of Li3PO4 polymorphs, see: West & Glasser (1972 ▶). For theo­retical studies of the redox potentials and Li migration paths of Li2MnSiO4, see: Kuganathan & Islam (2009 ▶); Mali et al. (2010 ▶); Duncan et al. (2011 ▶), and for NMR studies of this material, see: Sirisopanaporn et al. (2011 ▶). For the bond-valence method, see: Brown & Altermatt (1985 ▶). For crystallographic background, see: Cooper et al. (2002 ▶).

Experimental

Crystal data

Li2MnSiO4

M = 160.91

Orthorhombic,

a = 6.3133 (16) Å

b = 5.3677 (14) Å

c = 4.9685 (12) Å

V = 168.37 (7) Å3

Z = 2

Mo Kα radiation

μ = 4.11 mm−1

T = 295 K

0.26 × 0.19 × 0.18 mm

Data collection

Rigaku Mercury375R diffractometer

Absorption correction: multi-scan (REQAB; Rigaku, 1998 ▶) T min = 0.377, T max = 0.477

1636 measured reflections

423 independent reflections

419 reflections with I > 2σ(I)

R int = 0.019

Refinement

R[F 2 > 2σ(F 2)] = 0.015

wR(F 2) = 0.037

S = 1.14

423 reflections

45 parameters

1 restraint

Δρmax = 0.25 e Å−3

Δρmin = −0.62 e Å−3

Absolute structure: Flack (1983 ▶), 189 Friedel pairs

Flack parameter: 0.171 (15)

Data collection: CrystalClear (Rigaku, 2010 ▶); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: VESTA (Momma & Izumi, 2011 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812035040/wm2658sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812035040/wm2658Isup2.hkl

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

Li2MnSiO4	F(000) = 154
Mr = 160.91	Dx = 3.174 Mg m−3
Orthorhombic, Pmn21	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: P 2ac -2	Cell parameters from 1684 reflections
a = 6.3133 (16) Å	θ = 3.2–27.5°
b = 5.3677 (14) Å	µ = 4.11 mm−1
c = 4.9685 (12) Å	T = 295 K
V = 168.37 (7) Å3	Prism, light green
Z = 2	0.26 × 0.19 × 0.18 mm

Rigaku Mercury375R diffractometer	423 independent reflections
Radiation source: Sealed Tube	419 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.019
Detector resolution: 13.6612 pixels mm-1	θmax = 27.4°, θmin = 3.8°
profile data from ω–scans	h = −8→8
Absorption correction: multi-scan (REQAB; Rigaku, 1998)	k = −6→6
Tmin = 0.377, Tmax = 0.477	l = −6→6
1636 measured reflections

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	w = 1/[σ2(Fo2) + (0.0217P)2] where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.015	(Δ/σ)max < 0.001
wR(F2) = 0.037	Δρmax = 0.25 e Å−3
S = 1.14	Δρmin = −0.62 e Å−3
423 reflections	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
45 parameters	Extinction coefficient: 0.392 (13)
1 restraint	Absolute structure: Flack (1983), 189 Friedel pairs
0 constraints	Flack parameter: 0.171 (15)
Primary atom site location: structure-invariant direct methods

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
Li1	0.7503 (4)	−0.1688 (4)	0.995 (5)	0.0090 (7)
Mn1	0.5	0.33172 (5)	0.9968	0.00733 (15)
Si1	1	0.32090 (9)	0.9851 (3)	0.00350 (17)
O1	0.5	0.6868 (3)	1.1569 (5)	0.0071 (5)
O2	0.5	0.3867 (3)	0.5804 (4)	0.0081 (4)
O3	0.7887 (2)	0.1799 (2)	1.0979 (4)	0.0075 (3)

	U11	U22	U33	U12	U13	U23
Li1	0.0084 (17)	0.0061 (15)	0.0125 (15)	−0.0009 (7)	0.0000 (14)	−0.002 (2)
Mn1	0.0055 (2)	0.0072 (2)	0.0093 (2)	0	0	0.0000 (2)
Si1	0.0035 (3)	0.0028 (3)	0.0042 (4)	0	0	−0.0003 (3)
O1	0.0075 (9)	0.0083 (8)	0.0056 (11)	0	0	−0.0004 (6)
O2	0.0098 (8)	0.0048 (7)	0.0096 (10)	0	0	0.0001 (7)
O3	0.0068 (5)	0.0067 (6)	0.0089 (7)	−0.0009 (4)	0.0008 (7)	0.0000 (5)

Li1—O1i	1.936 (10)	Mn1—O1	2.065 (2)
Li1—O3	1.956 (6)	Mn1—O2	2.090 (2)
Li1—O3ii	1.99 (2)	Si1—O1v	1.631 (3)
Li1—O2iii	2.009 (6)	Si1—O3	1.6331 (17)
Mn1—O3iv	2.0585 (16)	Si1—O3vi	1.6331 (17)
Mn1—O3	2.0585 (15)	Si1—O2vii	1.639 (2)
O1i—Li1—O3	112.0 (7)	O3iv—Mn1—O2	107.31 (6)
O1i—Li1—O3ii	107.5 (5)	O3—Mn1—O2	107.31 (6)
O3—Li1—O3ii	107.7 (7)	O1—Mn1—O2	104.54 (8)
O1i—Li1—O2iii	108.6 (6)	O1v—Si1—O3	109.35 (10)
O3—Li1—O2iii	113.9 (5)	O1v—Si1—O3vi	109.35 (10)
O3ii—Li1—O2iii	106.8 (6)	O3—Si1—O3vi	109.58 (13)
O3iv—Mn1—O3	124.58 (8)	O1v—Si1—O2vii	108.23 (13)
O3iv—Mn1—O1	105.74 (5)	O3—Si1—O2vii	110.16 (10)
O3—Mn1—O1	105.74 (5)	O3vi—Si1—O2vii	110.16 (10)

Atom	Site	Present work	Dominko et al.1)	Arroyo-de Dompablo et al.2)
Li	4b	1.02 (6)	1.0 (1)	0.9
Mn	2a	1.89 (5)	2.1 (1)	1.77
Si	2a	3.89 (7)	3.6 (2)	3.65
O1	2a	2.02 (9)	1.9 (3)	1.75
O2	4b	1.97 (7)	1.9 (2)	1.86
O3	2a	1.87 (7)	2.0 (2)	1.90

Li1—O1i	1.936 (10)
Li1—O3	1.956 (6)
Li1—O3ii	1.99 (2)
Li1—O2iii	2.009 (6)
Mn1—O3iv	2.0585 (16)
Mn1—O1	2.065 (2)
Mn1—O2	2.090 (2)
Si1—O1v	1.631 (3)
Si1—O3	1.6331 (17)
Si1—O2vi	1.639 (2)

O1i—Li1—O3	112.0 (7)
O1i—Li1—O3ii	107.5 (5)
O3—Li1—O3ii	107.7 (7)
O1i—Li1—O2iii	108.6 (6)
O3—Li1—O2iii	113.9 (5)
O3ii—Li1—O2iii	106.8 (6)
O3iv—Mn1—O3	124.58 (8)
O3iv—Mn1—O1	105.74 (5)
O3iv—Mn1—O2	107.31 (6)
O1—Mn1—O2	104.54 (8)
O1v—Si1—O3	109.35 (10)
O3—Si1—O3vii	109.58 (13)
O1v—Si1—O2vi	108.23 (13)
O3—Si1—O2vi	110.16 (10)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) ; (vi) ; (vii) .

Table 2

Bond-valence parameters derived from the present model and the previous studies.

Atom	Site	Present work	Dominko et al. 1)	Arroyo-de Dompablo et al. 2)
Li	4b	1.02 (6)	1.0 (1)	0.9
Mn	2a	1.89 (5)	2.1 (1)	1.77
Si	2a	3.89 (7)	3.6 (2)	3.65
O1	2a	2.02 (9)	1.9 (3)	1.75
O2	4b	1.97 (7)	1.9 (2)	1.86
O3	2a	1.87 (7)	2.0 (2)	1.90

1) The data, referred to Dominko et al. (2006 ▶), are based on the coordinates for primary MO4 (M = Li, Mn, Si) tetra­hedra. 2) The data, referred to Arroyo-de Dompablo et al. (2008 ▶), are based on the coordinates for primary MO4 (M = Li, Mn, Si) tetra­hedra optimized by density functional theory (DFT) methods.