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Acta Cryst. (2008). E64, i39-i40    [ doi:10.1107/S160053680801516X ]

Lithium diaquamagnesium catena-borodiphosphate(V) monohydrate, LiMg(H2O)2[BP2O8]·H2O, at 173 K

J.-R. Lin, Y.-X. Huang, Y.-H. Wu and Y. Zhou

Abstract top

The crystal structure of LiMg(H2O)2[BP2O8]·H2O consists of tubular structural units, built from tetrahedral [infinity]1{[BP2O8]3-} borophosphate ribbons and (LiO4)n helices running along [001], which are interconnected by MgO4(H2O)2 octahedra, forming a three-dimensional network structure with one-dimensional channels along [001] in which the water molecules are located. The water molecule in the channel is significantly displaced by up to 0.3 Å from the special position 6b (..2) to a half-occupied general position. Mg, B and one Li atom all lie on twofold axes. Of the two Li positions, one is at a special position 6b (..2), while the other is at a general position; both are only half-occupied.

Comment top

In the last decade, much attention has been paid to the large family of borophosphates with the general formula AM(H2O)2[BP2O8].yH2O (AI=Li, Na, K, NH4+; MII=Mg, Mn, Fe, Co, Ni, Cu, Zn, Cd)(where y = 0.5–1) due to their chiral structure property and potential applications for catalysts (Kniep et al., 1997; Ewald et al., 2007). Many combinations between monovalent A cations and divalent M cations are available. At the M site, most of the known compounds in this family apply transition metal ions, while only two magnesium components, NaMg(H2O)2[BP2O8].H2O as well as KMg(H2O)2[BP2O8].H2O, are listed for the inclusion of alkaline-earth metals (Kniep et al., 1997). Whereas at the A site, up to date, only three Li-based borophosphates are known, e.g. LiCu(H2O)2[BP2O8].(H2O) (Boy & Kniep, 2001a), LiZn(H2O)2[BP2O8].H2O (Boy & Kniep, 2001b) and LiCd(H2O)2[BP2O8].H2O (Ge et al., 2003). Therefore herein we report on a new member of this family with the combination of Li and Mg, LiMg(H2O)2[BP2O8].H2O.

The crystal structure of the title compound contains infinite one-dimensional helical borophosphate ribbons ∞1{[BP2O8]3-}, arranged around 65 screw axes, which are built up from four-membered rings of corner-sharing PO4 and BO4 tetrahedra (Fig. 1 & 2). There are two partially occupied Li positions. Li1, located at the outside of ribbons (Fig. 2), is fixed by an irregular arrangement of five oxygen atoms from adjacent phosphate groups (O3) and water molecules (O5, O6). Li2 is tetrahedrally coordinated by four oxygen atoms that originated from phosphate groups (O4) and two water molecules (O5, O6)(Fig. 3). The resulting distorted tetrahedra, (Li2O4)n, located at the free thread of the borophosphate ribbons, are also wound around 65 screw axes to form helices via corner-sharing oxygen atoms which further connect the above infinite one-dimensional borophosphate ribbons by sharing common oxygen corners to develop into a tubular structure where water molecules (O6) with a disorder mode reside in. The magnesium site is octahedrally coordinated by four oxygen atoms from phosphate tetrahedra (O3, O4) and two water molecules (O5) which are located between the adjacent tubes and connect the neighbouring tubes to form a three-dimensional framework.

Related literature top

For the related structures NaMg(H2O)2[BP2O8].H2O and KMg(H2O)2[BP2O8].H2O, see: Kniep et al. (1997). For LiCu(H2O)2[BP2O8].(H2O) and LiZn(H2O)2[BP2O8].H2O, see: Boy & Kniep (2001a,b). For LiCd(H2O)2[BP2O8].H2O, see: Ge et al. (2003).

Experimental top

Transparent, colorless single crystals of the title compound were hydrothermally synthesized. A mixture of MgCl2.6H2O (0.5344 g), LiOH.H2O (5.042 g), H3BO3 (1.568 g) and 10 ml (85%) H3PO4 in an approximate molar ratio Mg:Li:B:P = 1:46:10:65, are dissolved in 5 ml distilled water while stirring. The resulting solution (pH = 1.5) was transferred into a Teflon-lined autoclave (internal volume 30 ml, degree of filling 67%) and held at 463 K for four days under autogenous pressure. Then the autoclave was cooled to room temperature by turning off the power. Products were filtered off, washed with distilled water and dried at room temperature. Crystals with hexagonal bipyramidal morphology were selected for single-crystal diffraction after checking under a polarizing microscope and identifying by X-ray powder diffraction.

Refinement top

The hydrogen atoms connected with O5 are located from the difference Fourier maps and fixed the positions and displacement parameters assigned as 0.05. The hydrogen positions for O6 are not determined due to the connecting water molecule in disorder mode. The occupancy of O6 was fixed to 0.5 in the last cycles of refinement because its refined value was close to 50%.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2005); cell refinement: CrysAlis CCD (Oxford Diffraction, 2005); data reduction: CrysAlis RED (Oxford Diffraction, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1997-2004) and ATOMS (Dowty, 2004); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Helical arrangements in the crystal structure of LiMg(H2O)2[BP2O8].H2O, Green tetrahedra: PO4, Orange tetrahedra: BO4, grey tetrahedra: Li2O4.
[Figure 2] Fig. 2. The crystal structure of LiMg(H2O)2[BP2O8].H2O plotted in projection along [001]
[Figure 3] Fig. 3. The coordination environment of the metal atoms in LiMg(H2O)2[BP2O8].H2O, with displacement ellipsoids drawn at the 50% probability level.(symmetry codes: (i) y, x, -1/3 - z; (ii) x-y, 1 - y, -z; (iii) x, 1 + x-y, -1/6 - z; (iv) 1 - x,1 - y,-1/2 + z; (v) -x + y, 1 - x, -2/3 + z; (vi) 1 + x-y, x, -1/6 + z; (vii) y, 1 - x + y, -5/6 + z; (viii) -x + y, y, -1/2 - z; (ix) 1 + x-y, 2 - y, -z)
Lithium diaquamagnesium catena-borodiphosphate(V) monohydrate top
Crystal data top
LiMg(H2O)2[BP2O8]·H2OZ = 6
Mr = 286.05F000 = 864
Hexagonal, P6522Dx = 2.364 Mg m−3
Hall symbol: P 65 2 (0 0 1)Mo Kα radiation
λ = 0.71073 Å
a = 9.41390 (10) ÅCell parameters from 3404 reflections
b = 9.41390 (10) Åθ = 2.8–32.6º
c = 15.7113 (3) ŵ = 0.67 mm−1
α = 90ºT = 173 (2) K
β = 90ºHexagonal bipyramidal, colourless
γ = 120º0.16 × 0.07 × 0.07 mm
V = 1205.82 (3) Å3
Data collection top
Oxford Diffraction CCD area-detector
diffractometer		1343 independent reflections
Radiation source: fine-focus sealed tube1142 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.033
T = 173(2) Kθmax = 32.6º
326 images,Δω=1°, Exp time: 40 s. scansθmin = 2.8º
Absorption correction: numerical
(CrysAlis RED; Oxford Diffraction, 2005)		h = −7→14
Tmin = 0.900, Tmax = 0.954k = −13→14
3404 measured reflectionsl = −22→8
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters not refined
R[F2 > 2σ(F2)] = 0.037  w = 1/[σ2(Fo2) + (0.0493P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.092(Δ/σ)max < 0.001
S = 1.06Δρmax = 0.74 e Å−3
1343 reflectionsΔρmin = −0.55 e Å−3
75 parametersExtinction correction: none
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), 410 Friedel pairs
Secondary atom site location: difference Fourier mapFlack parameter: −0.1 (2)
Crystal data top
LiMg(H2O)2[BP2O8]·H2Oγ = 120º
Mr = 286.05V = 1205.82 (3) Å3
Hexagonal, P6522Z = 6
a = 9.41390 (10) ÅMo Kα
b = 9.41390 (10) ŵ = 0.67 mm−1
c = 15.7113 (3) ÅT = 173 (2) K
α = 90º0.16 × 0.07 × 0.07 mm
β = 90º
Data collection top
Oxford Diffraction CCD area-detector
diffractometer		1343 independent reflections
Absorption correction: numerical
(CrysAlis RED; Oxford Diffraction, 2005)		1142 reflections with I > 2σ(I)
Tmin = 0.900, Tmax = 0.954Rint = 0.033
3404 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.037H-atom parameters not refined
wR(F2) = 0.092Δρmax = 0.74 e Å−3
S = 1.06Δρmin = −0.55 e Å−3
1343 reflectionsAbsolute structure: Flack (1983), 410 Friedel pairs
75 parametersFlack parameter: −0.1 (2)
Special details top

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 (Å2) top
xyzUiso*/UeqOcc. (<1)
P10.61413 (8)0.82894 (8)0.08573 (4)0.00616 (14)
Mg10.44657 (8)0.89313 (15)0.25000.0080 (3)
O10.8112 (2)0.7888 (2)−0.06431 (11)0.0096 (4)
O20.7643 (2)1.1783 (2)0.01261 (10)0.0074 (4)
O30.4841 (2)0.8559 (2)0.12481 (11)0.0113 (4)
O40.6190 (3)0.6808 (2)0.11749 (11)0.0116 (4)
O50.1958 (3)0.7110 (3)0.21628 (13)0.0168 (5)
B10.8496 (2)1.1504 (2)0.08330.0082 (7)
O60.8943 (11)0.8068 (7)0.2666 (4)0.0528 (18)*0.50
Li10.2395 (13)0.7605 (13)0.08330.027 (3)*0.426 (18)
Li20.893 (3)0.750 (3)0.3456 (13)0.027 (3)*0.287 (9)
H10.12730.66550.25750.050*
H20.19250.63060.18680.050*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
P10.0073 (3)0.0063 (3)0.0050 (2)0.0035 (2)0.0006 (2)−0.0002 (2)
Mg10.0081 (4)0.0074 (6)0.0084 (5)0.0037 (3)0.0018 (4)0.000
O10.0103 (9)0.0091 (9)0.0108 (8)0.0060 (8)−0.0029 (7)−0.0014 (7)
O20.0090 (9)0.0091 (9)0.0045 (7)0.0048 (8)−0.0006 (6)0.0004 (6)
O30.0124 (9)0.0166 (11)0.0067 (8)0.0087 (8)0.0006 (7)−0.0030 (7)
O40.0186 (10)0.0074 (9)0.0098 (7)0.0073 (8)−0.0013 (8)0.0012 (7)
O50.0132 (11)0.0124 (10)0.0160 (9)−0.0002 (9)0.0040 (8)−0.0044 (8)
B10.0100 (14)0.0100 (14)0.0065 (15)0.0063 (16)−0.0018 (13)−0.0018 (13)
Geometric parameters (Å, °) top
P1—O31.501 (2)B1—O1i1.461 (3)
P1—O41.5033 (19)B1—O2ix1.469 (3)
P1—O1i1.558 (2)B1—O21.469 (3)
P1—O2ii1.5632 (17)O6—O6iii0.549 (14)
P1—Li2iii2.94 (2)Li1—O3x2.113 (12)
Mg1—O4i2.042 (2)Li1—O5x2.135 (2)
Mg1—O4iv2.042 (2)Li1—O6vi2.35 (2)
Mg1—O3v2.0590 (17)Li1—O6iv2.35 (2)
Mg1—O32.0590 (17)Li1—Li2iv2.40 (3)
Mg1—O52.179 (2)Li2—O6iii1.82 (2)
Mg1—O5v2.179 (2)Li2—O4iii2.08 (2)
Mg1—Li2vi3.07 (2)Li2—O6vii2.08 (2)
Mg1—Li2vii3.07 (2)Li2—O5xi2.10 (2)
Mg1—Li1viii3.128 (4)Li2—Li2vii2.36 (4)
Mg1—Li13.128 (4)Li2—O6i2.48 (2)
B1—O1ii1.461 (3)Li2—O1xii2.65 (2)
O3—P1—O4115.28 (12)Li2iii—O6—Li2vii116.4 (10)
O3—P1—O1i111.30 (11)Li2—O6—Li1xi75.9 (9)
O4—P1—O1i105.63 (11)Li2iii—O6—Li1xi69.1 (7)
O3—P1—O2ii106.09 (10)Li2vii—O6—Li1xi114.4 (7)
O4—P1—O2ii111.75 (10)Li2—O6—Li2xiii117.5 (12)
O1i—P1—O2ii106.53 (10)Li2iii—O6—Li2xiii64.5 (10)
O3—P1—Li2iii134.1 (4)Li2vii—O6—Li2xiii142.5 (11)
O1i—P1—Li2iii63.9 (4)Li1xi—O6—Li2xiii101.1 (6)
O2ii—P1—Li2iii119.2 (4)O3x—Li1—O3109.7 (9)
O4i—Mg1—O4iv95.33 (13)O3x—Li1—O5x80.9 (3)
O4i—Mg1—O3v91.45 (8)O3—Li1—O5x97.7 (4)
O4iv—Mg1—O3v99.96 (8)O3x—Li1—O597.7 (4)
O4i—Mg1—O399.96 (8)O3—Li1—O580.9 (3)
O4iv—Mg1—O391.45 (8)O5x—Li1—O5177.4 (11)
O3v—Mg1—O3163.06 (13)O3x—Li1—O6vi125.3 (5)
O4i—Mg1—O5178.78 (8)O3—Li1—O6vi124.4 (5)
O4iv—Mg1—O585.31 (9)O5x—Li1—O6vi98.0 (6)
O3v—Mg1—O587.42 (8)O5—Li1—O6vi84.6 (5)
O3—Mg1—O581.04 (8)O3x—Li1—O6iv124.4 (5)
O4i—Mg1—O5v85.31 (9)O3—Li1—O6iv125.3 (5)
O4iv—Mg1—O5v178.78 (8)O5x—Li1—O6iv84.6 (5)
O3v—Mg1—O5v81.04 (8)O5—Li1—O6iv98.0 (6)
O3—Mg1—O5v87.42 (8)O6vi—Li1—O6iv13.5 (4)
O5—Mg1—O5v94.06 (13)O6—Li2—O6iii10.0 (7)
B1xiii—O1—P1xiii128.00 (16)O6—Li2—O4iii121.6 (14)
B1xiii—O1—Li2xii147.5 (5)O6iii—Li2—O4iii112.3 (11)
P1xiii—O1—Li2xii84.3 (5)O6—Li2—O6vii92.9 (11)
B1—O2—P1ii130.40 (17)O6iii—Li2—O6vii102.9 (10)
P1—O3—Mg1130.05 (11)O4iii—Li2—O6vii134.3 (10)
P1—O3—Li1127.6 (4)O6—Li2—O5xi121.0 (13)
Mg1—O3—Li197.1 (2)O6iii—Li2—O5xi119.2 (11)
P1—O4—Mg1xiii141.40 (12)O4iii—Li2—O5xi86.5 (8)
P1—O4—Li2iii109.2 (6)O6vii—Li2—O5xi101.1 (9)
Mg1xiii—O4—Li2iii96.3 (6)O6—Li2—O6i102.1 (12)
Li2vi—O5—Li169.3 (8)O6iii—Li2—O6i112.0 (10)
Li2vi—O5—Mg191.8 (6)O4iii—Li2—O6i125.2 (9)
Li1—O5—Mg192.95 (17)O6vii—Li2—O6i9.6 (4)
O1ii—B1—O1i102.5 (3)O5xi—Li2—O6i98.5 (8)
O1ii—B1—O2112.10 (10)O6—Li2—O1xii99.7 (11)
O1i—B1—O2114.14 (10)O6iii—Li2—O1xii98.7 (9)
O1ii—B1—O2ix114.14 (10)O4iii—Li2—O1xii60.6 (6)
O1i—B1—O2ix112.10 (10)O6vii—Li2—O1xii86.7 (7)
O2—B1—O2ix102.2 (3)O5xi—Li2—O1xii137.7 (9)
Li2—O6—Li2iii144.4 (15)O6i—Li2—O1xii82.4 (6)
Li2—O6—Li2vii84.1 (12)
Symmetry codes: (i) y, −x+y+1, z+1/6; (ii) x−y+1, −y+2, −z; (iii) −x+y+1, y, −z+1/2; (iv) −x+1, −x+y+1, −z+1/3; (v) −x+y, y, −z+1/2; (vi) x−y, x, z−1/6; (vii) y, x, −z+2/3; (viii) −x+y, −x+1, z+1/3; (ix) −y+2, −x+2, −z+1/6; (x) −y+1, −x+1, −z+1/6; (xi) y, −x+y, z+1/6; (xii) −x+2, −x+y+1, −z+1/3; (xiii) x−y+1, x, z−1/6.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O5—H1···O4v0.8622.0852.852 (3)147.93
O5—H2···O2xiv0.8751.9792.779 (3)151.43
O5—H2···O3x0.8752.4633.198 (3)141.96
Symmetry codes: (v) −x+y, y, −z+1/2; (xiv) y−1, −x+y, z+1/6; (x) −y+1, −x+1, −z+1/6.
Table 1
Selected geometric parameters (Å, °) top
P1—O31.501 (2)B1—O2iv1.469 (3)
P1—O41.5033 (19)Li1—O3v2.113 (12)
P1—O1i1.558 (2)Li1—O5v2.135 (2)
P1—O2ii1.5632 (17)Li1—O6vi2.35 (2)
Mg1—O4i2.042 (2)Li2—O6vii1.82 (2)
Mg1—O3iii2.0590 (17)Li2—O4vii2.08 (2)
Mg1—O52.179 (2)Li2—O6viii2.08 (2)
B1—O1ii1.461 (3)Li2—O5ix2.10 (2)
B1x—O1—P1x128.00 (16)P1—O3—Mg1130.05 (11)
B1—O2—P1ii130.40 (17)
Symmetry codes: (i) y, −x+y+1, z+1/6; (ii) x−y+1, −y+2, −z; (iii) −x+y, y, −z+1/2; (iv) −y+2, −x+2, −z+1/6; (v) −y+1, −x+1, −z+1/6; (vi) x−y, x, z−1/6; (vii) −x+y+1, y, −z+1/2; (viii) y, x, −z+2/3; (ix) y, −x+y, z+1/6; (x) x−y+1, x, z−1/6.
Table 2
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O5—H1···O4iii0.8622.0852.852 (3)147.93
O5—H2···O2xi0.8751.9792.779 (3)151.43
O5—H2···O3v0.8752.4633.198 (3)141.96
Symmetry codes: (iii) −x+y, y, −z+1/2; (xi) y−1, −x+y, z+1/6; (v) −y+1, −x+1, −z+1/6.
Acknowledgements top

This project was supported by the National Natural Science Foundation of China (No. 40472027).

references
References top

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