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A new compound, dilithium aluminium pentaborate, Li2Al­B5O10, has been synthesized by solid-state reaction and its structure determined by single-crystal X-ray diffraction. This compound is composed of [B5O10]5- groups linked by AlO4 tetrahedra. The [B5O10]5- group consists of two hexagonal B-­O rings perpendicular to each other connected by tetracoordinated boron. All the B-O rings in this structure can be divided into two groups, with one group approximately parallel and the other perpendicular to the c axis.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101006205/br1324sup1.cif
Contains datablocks labo, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270101006205/br1324Isup2.hkl
Contains datablock I

Comment top

This work is one of a series of studies aiming to explore new optical materials. Up to now, many optical materials have been found in borates. According to previous work (Cheng & Lu, 1997), the excellent optical properties of LiB3O5, one of the most important nonlinear optical crystals, mainly come from its anionic groups, [B3O7]5-. The [B3O7]5- group consists of two BO3 triangles and one BO4 tetrahedron and forms a hexagonal B—O ring. Hoping to synthesize new optical material, we are trying to introduce aluminium into alkali metal borates. Recently, a new compound, LiAlB2O5 (He et al., 2001) has been reported and its structure was determined from powder diffraction data. In this structure, Al substitutes the tetracoordinated B in [B3O7]5- rings and a new anionic group, [AlB2O7]5-, is formed. When the ratio of Li:(Al+B):O = 1:3:5 was kept but the ratio of Al:B was lowered to 1:5 from 1:2, the title compound was found to exist. This new compound crystallizes in a monoclinic space group P21/c and its structure can be characterized as a three-dimensional network of [B5O10]5- groups and AlO4 tetrahedra. The [B5O10]5- group consists of two planar hexagonal B—O rings linked by a tetracoordinated B and these two rings are perpendicular to each other. Moreover, all the B—O rings in this structure can be divided into two groups: one group is approximately parallel and the other perpendicular to the c axis (shown in Fig. 1). The unique configuration of planar B—O rings in this structure suggests that the title compound my be an excellent birefringent material. Unlike the Al atoms in LiAlB2O5, where Al atoms act much like tetracoordinated B, Al atoms in the title compound just connect with four different [B5O10]5- groups through O atoms and are not part of the B—O rings. In other words, [B5O10]5- groups are separated from each other completely by AlO4 tetrahedra. The Li+ cations are tetracoordinated with the Li—O distances ranging from 1.932 (2) to 2.063 (2) Å. The displacement ellipsoids of the asymmetry unit was shown in Fig. 2.

Experimental top

A powder mixture of Li2CO3 (0.7388 g, 10 mmol, Beijing Chemical Company, p.a.), Al2O3 (0.5098 g, 5 mmol, Beijing Chemical Company, p.a.) and H3BO3 (3.7098 g, 60 mmol, Beijing Chemical Company, p.a.) was melted at 1173 K in a Pt crucible. The melt was kept at 1173 K for 3 h to homogenize and then cooled to 1123 K at a rate of 10 K h-1 and to 1023 K at 2 K h-1. At last, the sample was further cooled to 673 K at a rate of 20 K h-1 and then the power of the furnace was cut off. The crucible was removed from the furnace after it had been cooled to room temperature. It was found that the title compound crystallized as transparent irregular grains. The X-ray powder diffraction pattern of the sample can be indexed with a unit cell that is given by the single-crystal data and shows some additional very weak reflections of LiB3O5.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SHELXTL (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1999); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The unit cell of Li2AlB5O10 viewed along [100]; large circles with crosses represent Al atoms, small ones Li while large open circles depict O and small open ones B.
[Figure 2] Fig. 2. The asymmetric unit of Li2AlB5O10. The displacement ellipsoids are drawn at the 50% probability level.
(I) top
Crystal data top
Li2AlB5O10F(000) = 496
Mr = 254.91Dx = 2.286 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71070 Å
a = 7.0402 (4) ÅCell parameters from 7060 reflections
b = 14.9404 (8) Åθ = 2.7–33.3°
c = 7.0433 (4) ŵ = 0.32 mm1
β = 90.702 (1)°T = 295 K
V = 740.78 (7) Å3Prism, colorless
Z = 40.20 × 0.15 × 0.10 mm
Data collection top
Bruker Apex CCD area detector
diffractometer
2491 reflections with I > 2s(I)
Radiation source: sealed tubeRint = 0.042
Graphite monochromatorθmax = 33.3°, θmin = 2.7°
ϕ and ω scansh = 109
6930 measured reflectionsk = 2318
2728 independent reflectionsl = 1010
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.034Secondary atom site location: difference Fourier map
wR(F2) = 0.107 w = 1/[σ2(Fo2) + (0.1P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.87(Δ/σ)max < 0.001
2728 reflectionsΔρmax = 0.48 e Å3
163 parametersΔρmin = 0.52 e Å3
Crystal data top
Li2AlB5O10V = 740.78 (7) Å3
Mr = 254.91Z = 4
Monoclinic, P21/cMo Kα radiation
a = 7.0402 (4) ŵ = 0.32 mm1
b = 14.9404 (8) ÅT = 295 K
c = 7.0433 (4) Å0.20 × 0.15 × 0.10 mm
β = 90.702 (1)°
Data collection top
Bruker Apex CCD area detector
diffractometer
2491 reflections with I > 2s(I)
6930 measured reflectionsRint = 0.042
2728 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.034163 parameters
wR(F2) = 0.1070 restraints
S = 0.87Δρmax = 0.48 e Å3
2728 reflectionsΔρmin = 0.52 e Å3
Special details top

Experimental. The title compound crystallized in the monoclinic system; space group P21/cf.rom the systematic absences.

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*/Ueq
Al10.14974 (4)0.375767 (17)0.03729 (4)0.00961 (10)
B10.20982 (15)0.27914 (7)0.02048 (15)0.01181 (18)
B20.20154 (14)0.47201 (7)0.40124 (14)0.01128 (18)
B30.24323 (14)0.49977 (7)0.26461 (14)0.01174 (18)
B40.45556 (14)0.24680 (7)0.00024 (14)0.01154 (18)
B50.67924 (15)0.12016 (6)0.00738 (16)0.01230 (19)
O10.07948 (10)0.34515 (5)0.03203 (10)0.01405 (15)
O20.27404 (10)0.27577 (5)0.01353 (11)0.01486 (15)
O30.14951 (11)0.40908 (5)0.27338 (10)0.01409 (15)
O40.24280 (11)0.46799 (5)0.08301 (10)0.01533 (15)
O50.28242 (10)0.55170 (4)0.35823 (10)0.01338 (15)
O60.16369 (10)0.44861 (4)0.58969 (10)0.01250 (14)
O70.49563 (10)0.15948 (4)0.02629 (11)0.01519 (15)
O80.16799 (10)0.19115 (5)0.00542 (11)0.01511 (15)
O90.39874 (10)0.30678 (4)0.03956 (10)0.01498 (15)
O100.31935 (11)0.58014 (5)0.30375 (10)0.01587 (15)
Li10.1033 (3)0.17197 (12)0.0005 (3)0.0190 (3)
Li20.3063 (3)0.57076 (13)0.0854 (3)0.0213 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Al10.00893 (15)0.00830 (15)0.01159 (15)0.00029 (8)0.00032 (10)0.00053 (8)
B10.0099 (4)0.0106 (4)0.0149 (4)0.0001 (3)0.0007 (3)0.0001 (3)
B20.0113 (4)0.0101 (4)0.0125 (4)0.0009 (3)0.0008 (3)0.0002 (3)
B30.0117 (4)0.0107 (4)0.0128 (4)0.0004 (3)0.0006 (3)0.0007 (3)
B40.0099 (4)0.0110 (4)0.0137 (4)0.0007 (3)0.0002 (3)0.0011 (3)
B50.0119 (4)0.0089 (4)0.0161 (4)0.0015 (3)0.0009 (3)0.0002 (3)
O10.0102 (3)0.0116 (3)0.0203 (3)0.0013 (2)0.0015 (2)0.0006 (2)
O20.0091 (3)0.0115 (3)0.0240 (3)0.0015 (2)0.0013 (2)0.0018 (2)
O30.0175 (3)0.0124 (3)0.0125 (3)0.0030 (2)0.0008 (2)0.0019 (2)
O40.0208 (4)0.0131 (3)0.0120 (3)0.0043 (2)0.0001 (2)0.0010 (2)
O50.0168 (3)0.0093 (3)0.0141 (3)0.0028 (2)0.0016 (2)0.0003 (2)
O60.0152 (3)0.0107 (3)0.0116 (3)0.0025 (2)0.0006 (2)0.0001 (2)
O70.0103 (3)0.0095 (3)0.0258 (4)0.0009 (2)0.0026 (3)0.0002 (2)
O80.0108 (3)0.0094 (3)0.0252 (3)0.0007 (2)0.0010 (3)0.0011 (2)
O90.0098 (3)0.0105 (3)0.0247 (4)0.0002 (2)0.0006 (2)0.0021 (2)
O100.0214 (4)0.0117 (3)0.0145 (3)0.0055 (2)0.0009 (3)0.0003 (2)
Li10.0167 (9)0.0126 (7)0.0277 (9)0.0002 (6)0.0009 (7)0.0015 (7)
Li20.0293 (10)0.0143 (8)0.0204 (9)0.0019 (7)0.0010 (7)0.0007 (7)
Geometric parameters (Å, º) top
Al1—O31.7357 (7)B5—O71.4421 (12)
Al1—O21.7405 (7)B5—O10v1.4586 (13)
Al1—O11.7414 (7)B5—O5vi1.4885 (12)
Al1—O41.7491 (7)B5—O8iv1.5124 (12)
Al1—Li13.0735 (19)Li2—O1i2.063 (2)
Al1—Li23.132 (2)Li1—O21.964 (2)
B1—O11.3502 (12)O3—Li1ii2.030 (2)
B1—O81.3591 (12)Li2—O41.988 (2)
B1—O91.3976 (12)O5—B5vii1.4885 (12)
B1—Li2i2.386 (2)Li2—O51.952 (2)
B1—Li12.727 (2)O6—B3viii1.3917 (12)
B2—O31.3495 (11)O6—Li1ii1.955 (2)
B2—O51.3556 (12)O8—B5ix1.5124 (12)
B2—O61.4013 (12)Li1—O81.932 (2)
B2—Li1ii2.366 (2)O9—B4ix1.3931 (12)
B2—Li22.776 (2)O9—Li2i1.970 (2)
B3—O101.3447 (12)O10—B5x1.4586 (13)
B3—O41.3644 (12)Li1—O6xi1.955 (2)
B3—O6iii1.3917 (12)Li1—O3xi2.030 (2)
B3—Li22.715 (2)Li1—B2xi2.366 (2)
B4—O71.3469 (12)Li2—O9i1.970 (2)
B4—O21.3536 (12)Li2—O1i2.063 (2)
B4—O9iv1.3931 (12)Li2—B1i2.386 (2)
B4—Li12.720 (2)
O3—Al1—O2110.16 (4)B3viii—O6—B2118.81 (7)
O3—Al1—O1109.40 (4)B3viii—O6—Li1ii146.06 (8)
O2—Al1—O1102.29 (4)B2—O6—Li1ii88.00 (8)
O3—Al1—O4104.06 (3)B4—O7—B5123.97 (8)
O2—Al1—O4115.96 (4)B1—O8—B5ix121.17 (8)
O1—Al1—O4114.99 (4)B1—O8—Li1110.68 (8)
O3—Al1—Li1111.45 (5)B5ix—O8—Li1126.66 (8)
O2—Al1—Li136.33 (4)B4ix—O9—B1119.52 (7)
O1—Al1—Li167.56 (4)B4ix—O9—Li2i151.17 (9)
O4—Al1—Li1141.12 (5)B1—O9—Li2i88.52 (8)
O3—Al1—Li268.53 (4)B3—O10—B5x124.07 (8)
O2—Al1—Li2129.22 (5)O8—Li1—O6xi109.91 (10)
O1—Al1—Li2126.75 (5)O8—Li1—O2119.10 (10)
O4—Al1—Li235.53 (4)O6xi—Li1—O2125.50 (10)
Li1—Al1—Li2165.44 (5)O8—Li1—O3xi105.87 (9)
O1—B1—O8124.63 (9)O6xi—Li1—O3xi70.67 (7)
O1—B1—O9115.16 (8)O2—Li1—O3xi114.00 (10)
O8—B1—O9120.21 (9)O8—Li1—B2xi115.71 (9)
O1—B1—Li2i59.60 (7)O6xi—Li1—B2xi36.30 (4)
O8—B1—Li2i174.70 (9)O2—Li1—B2xi123.50 (10)
O9—B1—Li2i55.64 (7)O3xi—Li1—B2xi34.70 (4)
O1—B1—Li183.24 (7)O8—Li1—B127.79 (4)
O8—B1—Li141.53 (6)O6xi—Li1—B1136.90 (10)
O9—B1—Li1161.13 (8)O2—Li1—B191.88 (7)
Li2i—B1—Li1142.17 (8)O3xi—Li1—B1116.56 (9)
O3—B2—O5125.04 (9)B2xi—Li1—B1139.28 (9)
O3—B2—O6113.89 (8)O8—Li1—B4147.18 (10)
O5—B2—O6121.07 (8)O6xi—Li1—B4100.57 (8)
O3—B2—Li1ii58.91 (7)O2—Li1—B428.11 (4)
O5—B2—Li1ii171.53 (9)O3xi—Li1—B495.27 (8)
O6—B2—Li1ii55.70 (6)B2xi—Li1—B496.00 (7)
O3—B2—Li284.73 (7)B1—Li1—B4119.68 (7)
O5—B2—Li240.35 (6)O8—Li1—Al187.44 (7)
O6—B2—Li2161.25 (8)O6xi—Li1—Al1149.55 (9)
Li1ii—B2—Li2143.03 (8)O2—Li1—Al131.67 (4)
O10—B3—O4120.56 (8)O3xi—Li1—Al1129.87 (9)
O10—B3—O6iii119.80 (8)B2xi—Li1—Al1153.51 (9)
O4—B3—O6iii119.64 (8)B1—Li1—Al160.52 (4)
O10—B3—Li277.07 (7)B4—Li1—Al159.78 (4)
O4—B3—Li244.52 (6)O5—Li2—O9i109.24 (10)
O6iii—B3—Li2160.70 (8)O5—Li2—O4116.96 (10)
O7—B4—O2119.78 (9)O9i—Li2—O4133.78 (11)
O7—B4—O9iv119.80 (8)O5—Li2—O1i101.10 (10)
O2—B4—O9iv120.42 (8)O9i—Li2—O1i70.19 (7)
O7—B4—Li177.97 (7)O4—Li2—O1i101.18 (9)
O2—B4—Li143.12 (6)O5—Li2—B1i107.35 (9)
O9iv—B4—Li1159.62 (8)O9i—Li2—B1i35.85 (5)
O7—B5—O10v109.46 (8)O4—Li2—B1i123.39 (10)
O7—B5—O5vi108.60 (8)O1i—Li2—B1i34.37 (4)
O10v—B5—O5vi111.03 (7)O5—Li2—B3145.27 (10)
O7—B5—O8iv110.04 (7)O9i—Li2—B3105.34 (8)
O10v—B5—O8iv109.21 (8)O4—Li2—B328.77 (4)
O5vi—B5—O8iv108.49 (8)O1i—Li2—B387.41 (7)
B1—O1—Al1143.43 (6)B1i—Li2—B398.64 (8)
B1—O1—Li2i86.03 (8)O5—Li2—B226.72 (4)
Al1—O1—Li2i127.13 (7)O9i—Li2—B2135.76 (10)
B4—O2—Al1139.23 (7)O4—Li2—B290.44 (7)
B4—O2—Li1108.77 (8)O1i—Li2—B2104.90 (9)
Al1—O2—Li1111.99 (7)B1i—Li2—B2125.12 (9)
B2—O3—Al1146.68 (7)B3—Li2—B2118.55 (8)
B2—O3—Li1ii86.39 (8)O5—Li2—Al186.36 (7)
Al1—O3—Li1ii125.63 (7)O9i—Li2—Al1164.32 (9)
B3—O4—Al1137.18 (6)O4—Li2—Al130.75 (4)
B3—O4—Li2106.71 (8)O1i—Li2—Al1106.04 (8)
Al1—O4—Li2113.72 (7)B1i—Li2—Al1139.00 (9)
B2—O5—B5vii121.25 (8)B3—Li2—Al159.00 (4)
B2—O5—Li2112.93 (8)B2—Li2—Al159.73 (4)
B5vii—O5—Li2125.28 (8)
Symmetry codes: (i) x, y+1, z; (ii) x, y+1/2, z+1/2; (iii) x, y, z1; (iv) x+1, y, z; (v) x+1, y1/2, z1/2; (vi) x+1, y1/2, z+1/2; (vii) x+1, y+1/2, z+1/2; (viii) x, y, z+1; (ix) x1, y, z; (x) x+1, y+1/2, z1/2; (xi) x, y+1/2, z1/2.

Experimental details

Crystal data
Chemical formulaLi2AlB5O10
Mr254.91
Crystal system, space groupMonoclinic, P21/c
Temperature (K)295
a, b, c (Å)7.0402 (4), 14.9404 (8), 7.0433 (4)
β (°) 90.702 (1)
V3)740.78 (7)
Z4
Radiation typeMo Kα
µ (mm1)0.32
Crystal size (mm)0.20 × 0.15 × 0.10
Data collection
DiffractometerBruker Apex CCD area detector
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2s(I)] reflections
6930, 2728, 2491
Rint0.042
(sin θ/λ)max1)0.773
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.034, 0.107, 0.87
No. of reflections2728
No. of parameters163
Δρmax, Δρmin (e Å3)0.48, 0.52

Computer programs: SMART (Bruker, 2000), SMART, SHELXTL (Bruker, 2000), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1999), SHELXL97.

Selected bond lengths (Å) top
Al1—O31.7357 (7)B4—O21.3536 (12)
Al1—O21.7405 (7)B4—O9ii1.3931 (12)
Al1—O11.7414 (7)B5—O71.4421 (12)
Al1—O41.7491 (7)B5—O10iii1.4586 (13)
B1—O11.3502 (12)B5—O5iv1.4885 (12)
B1—O81.3591 (12)B5—O8ii1.5124 (12)
B1—O91.3976 (12)Li1—O21.964 (2)
B2—O31.3495 (11)Li2—O41.988 (2)
B2—O51.3556 (12)Li2—O51.952 (2)
B2—O61.4013 (12)Li1—O81.932 (2)
B3—O101.3447 (12)Li1—O6v1.955 (2)
B3—O41.3644 (12)Li1—O3v2.030 (2)
B3—O6i1.3917 (12)Li2—O9vi1.970 (2)
B4—O71.3469 (12)Li2—O1vi2.063 (2)
Symmetry codes: (i) x, y, z1; (ii) x+1, y, z; (iii) x+1, y1/2, z1/2; (iv) x+1, y1/2, z+1/2; (v) x, y+1/2, z1/2; (vi) x, y+1, z.
 

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