The monoclinic form of trilithium dichromium(III) tris-(orthophosphate).

The monoclinic form of trilithium dichromium(III) tris-(ortho-phosphate), Li3Cr2(PO4)3, was prepared by the reactive halide flux method. The structure of the title compound is composed of a three-dimensional anionic framework with composition ∞ (3)[Cr2(PO4)3](3-) and Li(+) ions situated in the empty channels. The rigid framework built up from CrO6 octa-hedra and PO4 tetra-hedra is the same as that found in other monoclinic Li3 M 2(PO4)3 (M = Fe, Sc, V) phases. The three Li(+) cations of Li3Cr2(PO4)3 are unequally disordered over six crystallographically different sites. The classical charge balance of the title compound can be represented as [Li(+)]3[Cr(3+)]2[P(5+)]3[O(2-)]12. Solid-state UV/Vis spectra indicate that the crystal filed splitting (Δ0) of the Cr(3+) ion is around 2.22 eV.

Related literature

For the structures of Li3 M 2(PO4)3 (M = Fe, Sc, Cr, V), see: d’Yvoire et al. (1983 ▶); Verin et al. (1985 ▶); Maksimov et al. (1986 ▶). The structures of the ortho­rhom­bic form of Li3Cr2(PO4)3 have been investigated by Genkina et al. (1991 ▶). Structural studies of Li3V2(PO4)3 based on single-crystal data have been reported previously by Kee & Yun (2013 ▶). The general structural features of the monoclinic phases have been discussed by Patoux et al. (2003 ▶); Fu et al. (2010 ▶); Yang et al. (2010 ▶). For ionic radii, see: Shannon (1976 ▶).

Experimental

Crystal data

Li3Cr2(PO4)3

M = 409.73

Monoclinic,

a = 8.4625 (4) Å

b = 8.5560 (3) Å

c = 14.5344 (5) Å

β = 125.186 (2)°

V = 860.08 (6) Å3

Z = 4

Mo Kα radiation

μ = 3.16 mm−1

T = 290 K

0.36 × 0.12 × 0.10 mm

Data collection

Rigaku R-AXIS RAPID S diffractometer

Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T min = 0.688, T max = 1.000

8163 measured reflections

1962 independent reflections

1887 reflections with I > 2σ(I)

R int = 0.021

Refinement

R[F 2 > 2σ(F 2)] = 0.026

wR(F 2) = 0.068

S = 1.14

1962 reflections

184 parameters

1 restraint

Δρmax = 0.71 e Å−3

Δρmin = −0.71 e Å−3

Data collection: RAPID-AUTO (Rigaku, 2006 ▶); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 1999 ▶); software used to prepare material for publication: WinGX (Farrugia, 2012 ▶) and publCIF (Westrip, 2010 ▶).

Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S1600536813026433/wm2772sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813026433/wm2772Isup2.hkl

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

Li3Cr2(PO4)3	F(000) = 792
Mr = 409.73	Dx = 3.164 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 8071 reflections
a = 8.4625 (4) Å	θ = 3.4–27.7°
b = 8.5560 (3) Å	µ = 3.16 mm−1
c = 14.5344 (5) Å	T = 290 K
β = 125.186 (2)°	Block, green
V = 860.08 (6) Å3	0.36 × 0.12 × 0.10 mm
Z = 4

Rigaku R-AXIS RAPID S diffractometer	1962 independent reflections
Radiation source: Sealed X-ray tube	1887 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.021
ω scans	θmax = 27.5°, θmin = 3.4°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	h = −10→10
Tmin = 0.688, Tmax = 1.000	k = −11→10
8163 measured reflections	l = −18→18

Refinement on F2	1 restraint
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.026	Secondary atom site location: difference Fourier map
wR(F2) = 0.068	w = 1/[σ2(Fo2) + (0.0319P)2 + 1.8772P] where P = (Fo2 + 2Fc2)/3
S = 1.14	(Δ/σ)max < 0.001
1962 reflections	Δρmax = 0.71 e Å−3
184 parameters	Δρmin = −0.71 e Å−3

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.

	x	y	z	Uiso*/Ueq	Occ. (<1)
Li1	0.4750 (10)	0.2119 (8)	0.1752 (6)	0.022 (2)*	0.71 (2)
Li2	0.104 (2)	0.208 (2)	0.3364 (14)	0.022 (6)*	0.30 (2)
Li3	0.1164 (11)	0.5885 (9)	0.1920 (7)	0.017 (3)*	0.59 (2)
Li4	0.1935 (14)	0.1892 (12)	0.2627 (8)	0.036 (3)*	0.64 (3)
Li5	0.672 (3)	0.227 (2)	0.2586 (15)	0.019 (6)*	0.27 (2)
Li6	0.273 (3)	0.059 (3)	0.1835 (19)	0.072 (8)*	0.48 (3)
Cr1	0.36305 (5)	0.53352 (4)	0.11142 (3)	0.00608 (11)
Cr2	0.13604 (5)	0.53218 (5)	0.38801 (3)	0.00787 (11)
P1	0.46068 (8)	0.39077 (7)	0.35382 (5)	0.00707 (13)
P2	0.75261 (8)	0.38724 (7)	0.14717 (5)	0.00693 (13)
P3	0.04107 (8)	0.25059 (7)	0.00513 (5)	0.00717 (13)
O1	0.6057 (2)	0.4162 (2)	0.17588 (15)	0.0129 (4)
O2	0.2909 (3)	0.3809 (2)	0.36484 (16)	0.0138 (4)
O3	0.5955 (3)	0.0119 (2)	0.23933 (16)	0.0181 (4)
O4	0.0766 (3)	0.0017 (2)	0.27885 (15)	0.0124 (3)
O5	0.6674 (3)	0.4170 (2)	0.02547 (15)	0.0135 (4)
O6	0.3515 (3)	0.5558 (2)	0.54233 (16)	0.0197 (4)
O7	0.1224 (3)	0.6330 (2)	0.06579 (16)	0.0135 (4)
O8	0.0340 (2)	0.1757 (2)	0.09856 (15)	0.0135 (4)
O9	0.2391 (2)	0.3295 (2)	0.06304 (17)	0.0166 (4)
O10	0.0217 (3)	0.3652 (2)	0.41922 (16)	0.0156 (4)
O11	0.4784 (2)	0.2282 (2)	0.31441 (14)	0.0106 (3)
O12	0.1852 (3)	0.7155 (2)	0.32091 (15)	0.0140 (4)

	U11	U22	U33	U12	U13	U23
Cr1	0.00427 (18)	0.00702 (19)	0.00645 (19)	0.00016 (12)	0.00280 (15)	0.00019 (13)
Cr2	0.00503 (18)	0.0106 (2)	0.00828 (19)	−0.00115 (13)	0.00402 (15)	−0.00151 (14)
P1	0.0064 (3)	0.0078 (3)	0.0061 (3)	0.0019 (2)	0.0030 (2)	0.0007 (2)
P2	0.0054 (3)	0.0085 (3)	0.0063 (3)	0.0014 (2)	0.0031 (2)	0.0000 (2)
P3	0.0053 (3)	0.0063 (3)	0.0100 (3)	−0.0001 (2)	0.0045 (2)	−0.0001 (2)
O1	0.0089 (8)	0.0216 (9)	0.0095 (8)	0.0060 (7)	0.0060 (7)	0.0022 (7)
O2	0.0112 (8)	0.0133 (8)	0.0197 (9)	−0.0001 (7)	0.0106 (7)	−0.0023 (7)
O3	0.0348 (11)	0.0105 (8)	0.0154 (9)	−0.0066 (8)	0.0182 (9)	−0.0043 (7)
O4	0.0105 (8)	0.0128 (8)	0.0095 (8)	0.0013 (7)	0.0033 (7)	0.0010 (7)
O5	0.0140 (8)	0.0171 (9)	0.0089 (8)	0.0027 (7)	0.0062 (7)	0.0018 (7)
O6	0.0117 (9)	0.0235 (10)	0.0146 (9)	−0.0025 (8)	0.0023 (8)	−0.0065 (8)
O7	0.0117 (8)	0.0122 (8)	0.0186 (9)	0.0053 (7)	0.0099 (7)	0.0053 (7)
O8	0.0100 (8)	0.0180 (9)	0.0108 (8)	−0.0009 (7)	0.0050 (7)	0.0038 (7)
O9	0.0076 (8)	0.0083 (8)	0.0302 (11)	−0.0018 (7)	0.0087 (8)	−0.0017 (8)
O10	0.0115 (8)	0.0191 (9)	0.0157 (9)	−0.0037 (7)	0.0075 (7)	0.0043 (7)
O11	0.0125 (8)	0.0081 (8)	0.0086 (8)	0.0038 (6)	0.0045 (7)	0.0002 (6)
O12	0.0216 (9)	0.0100 (8)	0.0151 (8)	−0.0057 (7)	0.0133 (8)	−0.0041 (7)

Li1—O3	1.934 (7)	Cr1—O5v	1.9007 (18)
Li1—O9	1.977 (7)	Cr1—O7	1.9380 (17)
Li1—O11	2.011 (7)	Cr1—O9	1.9471 (18)
Li1—O1	2.066 (7)	Cr1—O1	1.9709 (17)
Li2—O4	1.908 (17)	Cr1—O3iii	1.9965 (18)
Li2—O2	2.028 (17)	Cr1—O11iii	2.0172 (17)
Li2—O10	2.170 (17)	Cr2—O6	1.9192 (19)
Li2—O12i	2.184 (17)	Cr2—O10	1.9208 (18)
Li3—O7	1.902 (8)	Cr2—O8ii	1.9847 (18)
Li3—O12	1.943 (8)	Cr2—O2	2.0041 (18)
Li3—O4ii	2.049 (8)	Cr2—O12	2.0129 (18)
Li3—O3iii	2.137 (8)	Cr2—O4ii	2.0392 (18)
Li4—O8	1.953 (10)	P1—O6vi	1.4994 (19)
Li4—O4	1.969 (10)	P1—O2	1.5368 (18)
Li4—O2	2.040 (10)	P1—O11	1.5443 (17)
Li4—O11	2.098 (10)	P1—O3iii	1.5463 (19)
Li5—O1	1.900 (18)	P2—O5	1.4979 (18)
Li5—O3	1.916 (18)	P2—O12iv	1.5394 (18)
Li5—O12iv	2.103 (18)	P2—O1	1.5424 (17)
Li5—O11	2.206 (18)	P2—O4iii	1.5532 (18)
Li5—O7iv	2.252 (18)	P3—O7vii	1.5248 (18)
Li6—O8	1.93 (2)	P3—O10viii	1.5268 (19)
Li6—O1iv	2.08 (2)	P3—O9	1.5319 (18)
Li6—O11	2.22 (2)	P3—O8	1.5337 (18)
Li6—O3	2.39 (2)
O5v—Cr1—O7	93.57 (8)	O2—Cr2—O12	94.84 (8)
O5v—Cr1—O9	95.83 (9)	O6—Cr2—O4ii	175.15 (8)
O7—Cr1—O9	91.63 (8)	O10—Cr2—O4ii	88.07 (8)
O5v—Cr1—O1	94.97 (8)	O8ii—Cr2—O4ii	90.18 (7)
O7—Cr1—O1	171.08 (8)	O2—Cr2—O4ii	86.09 (8)
O9—Cr1—O1	84.97 (8)	O12—Cr2—O4ii	79.09 (8)
O5v—Cr1—O3iii	172.27 (8)	O6vi—P1—O2	115.09 (11)
O7—Cr1—O3iii	84.53 (8)	O6vi—P1—O11	112.02 (11)
O9—Cr1—O3iii	91.72 (9)	O2—P1—O11	106.60 (10)
O1—Cr1—O3iii	87.34 (8)	O6vi—P1—O3iii	106.84 (12)
O5v—Cr1—O11iii	91.32 (8)	O2—P1—O3iii	107.11 (11)
O7—Cr1—O11iii	93.70 (8)	O11—P1—O3iii	108.98 (10)
O9—Cr1—O11iii	170.80 (8)	O5—P2—O12iv	111.51 (10)
O1—Cr1—O11iii	88.66 (8)	O5—P2—O1	112.18 (10)
O3iii—Cr1—O11iii	81.34 (8)	O12iv—P2—O1	105.13 (10)
O6—Cr2—O10	94.07 (9)	O5—P2—O4iii	109.45 (11)
O6—Cr2—O8ii	94.27 (8)	O12iv—P2—O4iii	111.89 (10)
O10—Cr2—O8ii	86.83 (8)	O1—P2—O4iii	106.55 (10)
O6—Cr2—O2	89.50 (8)	O7vii—P3—O10viii	104.06 (10)
O10—Cr2—O2	91.50 (8)	O7vii—P3—O9	111.22 (10)
O8ii—Cr2—O2	175.97 (8)	O10viii—P3—O9	107.65 (11)
O6—Cr2—O12	99.31 (8)	O7vii—P3—O8	112.88 (10)
O10—Cr2—O12	165.23 (8)	O10viii—P3—O8	114.36 (11)
O8ii—Cr2—O12	85.96 (8)	O9—P3—O8	106.63 (11)