The intermetallic compound BaAgBi

Acta Cryst.(2002). E58, i21±i22 DOI: 10.1107/S1600536802001721 Kang and Miller AgBaBi

i21

inorganic papers

Acta Crystallographica Section E

Structure Reports

Online ISSN 1600-5368

The intermetallic compound BaAgBi

Sung Kwon Kanga_{* and Gordon J.}

Millerb

a_{Department of Chemistry, Chungnam National}

University, Daejeon, 305-764, South Korea, and

b_{Department of Chemistry, Iowa State}

University, Ames, IA 50011, USA

Correspondence e-mail: [email protected]

Key indicators Single-crystal X-ray study T= 293 K

Mean(Ag±Ba) = 0.0004 AÊ Rfactor = 0.038 wRfactor = 0.102

Data-to-parameter ratio = 16.6

For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.

#2002 International Union of Crystallography Printed in Great Britain ± all rights reserved

Barium silver bismuth is isostructural with ZrBeSi. The Ag and Bi atoms form planar honeycomb layers with an AgÐBi distance of 2.8534 (4) AÊ. The displacement parameters of Ag and Bi show a strong anisotropy.

Comment

During studies on the ternary barium±silver±bismuth system, the intermetallic compound BaAgBi was obtained as a side product. Previously, this compound was prepared by stoi-chiometric reaction of the elements and characterized by X-ray powder diffraction (Merloet al., 1990).

BaAgBi is isostructural with ZrBeSi (Vogel & Schuster, 1980). The Ag and Bi atoms form planar hexagonal sheets like graphite, with Ag and Bi alternating in the layer. The Ba atoms lie between two layers and are positioned over the centers of the hexagonal rings. The shortest interatomic distance, AgÐ Bi, is 2.8534 (4) AÊ, and each Ba atom is surrounded by six Au and six Sb atoms at distances of 3.6533 (4) AÊ. The displace-ment parameters of the Ag and Bi atoms display a strong anisotropy; the U11 values of the Ag and Bi atoms are

0.0120 (11) and 0.0066 (7) AÊ2 _{while the U}

33 values are

0.0231 (18) and 0.0140 (10) AÊ2_{, respectively. This anisotropy}

also appears in several ZrBeSi-type compounds, such as EuZnGe (PoÈttgen, 1995), CaCuBi (Merlo et al., 1990), and EuAgAs (Tomuschat & Schuster, 1981), suggesting the possibility of interlayer interactions.

Received 17 January 2002 Accepted 28 January 2002 Online 8 February 2002

Figure 1

Experimental

BaAgBi was obtained as a by-product when Ba [rod, Alfa±Aesar (99.99%)], Ag [powder,ÿ100 mesh, Alfa±Aesar (99.999%)], and Bi [powder, ÿ100 mesh, Alfa±Aesar (99.999%)] were loaded into a tantalum tube (Nobel-Met. Ltd, >99.85%, 0.375 in. OD) in a 1:1:2 molar ratio in an Ar-®lled glovebox. The tube was sealed in an arc-melter under argon, placed in a fused-silica jacket, and heated at 973 K for 3 days. The reaction container was cooled slowly to 673 K at 10 K hÿ1_{, and then quenched to room temperature. When the}

tantalum tube was opened in the Ar-®lled glovebox, grey irregular-shaped crystals of BaAgBi were found in the product. Single crystals were mounted in 0.3 mm thin-walled capillaries for diffraction experiments.

Crystal data

AgBaBi

Mr= 454.19 Hexagonal,P63=mmc a= 4.9423 (7) AÊ

c= 9.1251 (18) AÊ

V= 193.03 (5) AÊ3 Z= 2

Dx= 7.814 Mg mÿ3

MoKradiation Cell parameters from 27

re¯ections = 6.5±14.4 = 60.31 mmÿ1 T= 293 (2) K Irregular, grey 0.090.030.03 mm

Data collection

Rigaku AFC-6Rdiffractometer 2/!scans

Absorption correction: scan (Northet al., 1968)

Tmin= 0.132,Tmax= 0.164

133 measured re¯ections 133 independent re¯ections 89 re¯ections withI> 2(I)

max= 30.0 h= 0!6

k= 0!3

l= 0!12

3 standard re¯ections every 100 re¯ections intensity decay: 0.9%

Re®nement

Re®nement onF2 R[F2_{> 2(F}2_{)] = 0.038} wR(F2_{) = 0.102} S= 1.16 133 re¯ections 8 parameters

w= 1/[2_(F

o2) + (0.0405P)2 + 2.2564P]

whereP= (Fo2+ 2Fc2)/3 (/)max< 0.001

max= 2.76 e AÊÿ3

min=ÿ3.98 e AÊÿ3

Extinction correction:SHELXL

Extinction coef®cient: 0.011 (2)

Table 1

Selected geometric parameters (AÊ,_).

BaÐBii _{3.6533 (4)}

BaÐAg 3.6533 (4) AgÐBi

ii _{2.8534 (4)}

Biii_ÐAgÐBiiii _{120 Ag}ii_ÐBiÐAgiii ₁₂₀

Symmetry codes: (i) 1ÿx;1ÿy;1ÿz; (ii) 1ÿx;2ÿy;1ÿz; (iii)ÿx;1ÿy;1ÿz.

Based on the observed systematic absences, space groupsP31c,

P31c,P63mc,P63/mmc, andP62care allowed. Space groupP63/mmc

was initially selected and con®rmed by comparing the re®nement results with those of the other four space groups. The Ba, Ag, and Bi atoms were readily located from theEmap, and re®ned with aniso-tropic displacement parameters. The re¯ection 124 was omitted from the re®nement because of possible interference from the beam stop of the X-ray diffractometer. The largest residuals in the ®nal differ-ence map were 2.76 e AÊÿ3_{at a distance of 0.74 AÊ from Bi, andÿ3.98e}

AÊÿ3_{at a distance of 0.92 AÊ from Bi.}

Data collection: TEXSAN (Molecular Structure Corporation, 1990); cell re®nement: TEXSAN; data reduction: TEXSAN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to re®ne structure:SHELXL97 (Sheldrick, 1997); software used to prepare material for publication:WinGX(Farrugia, 1999).

The authors wish to acknowledge the ®nancial support of the Korean Research Foundation made in the programme year of 2000 (project No. DP0222).

References

Farrugia, L. J. (1999).J. Appl. Cryst.32, 837±838.

Merlo, F., Pani, M. & Fornasini, M. L. (1990).J. Less Common Met.166, 319± 327.

Molecular Structure Corporation (1990).TEXSAN.Version 6.0. MSC, 3200 Research Forest Drive, The Woodlands, TX 77381, USA.

North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968).Acta Cryst, A24, 351± 359.

PoÈttgen, R. (1995).Z. Kristallogr.210, 924±928.

Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of GoÈttingen, Germany.

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Acta Cryst. (2002). E58, i21–i22 [doi:10.1107/S1600536802001721]

The intermetallic compound BaAgBi

Sung Kwon Kang and Gordon J. Miller

S1. Comment

During studies on the ternary barium–silver–bismuth system, the intermetallic compound BaAgBi was obtained as a side

product. Previously, this compound was prepared by stoichiometric reaction of the elements and characterized by X-ray

powder diffraction (Merlo et al., 1990).

BaAgBi is isostructural with ZrBeSi (Vogel & Schuster, 1980). The Ag and Bi atoms form planar hexagonal sheets like

graphite, with Ag and Bi alternating in the layer. The Ba atoms lie between two layers and are positioned over the centers

of the hexagonal rings. The shortest interatomic distance, Ag—Bi, is 2.8534 (4) Å, and each Ba atom is surrounded by six

Au and six Sb atoms at distances of 3.6533 (4) Å. The displacement parameters of the Ag and Bi atoms display a strong

anisotropy; the U11 values of the Ag and Bi atoms are 0.0120 (11) and 0.0066 (7) Å2 while the U33 values are 0.0231 (18)

and 0.0140 (10) Å2_{, respectively. This anisotropy also appears in several ZrBeSi-type compounds, such as EuZnGe}

(Pöttgen, 1995), CaCuBi (Merlo et al., 1990), and EuAgAs (Tomuschat & Schuster, 1981), suggesting the possibility of

interlayer interactions.

S2. Experimental

BaAgBi was obtained as a by-product when Ba [rod, Alfa-Aesar (99.99%)], Ag [powder, -100 mesh, Alfa-Aesar

(99.999%)], and Bi [powder, -100 mesh, Alfa-Aesar (99.999%)] were loaded into a tantalum tube (Nobel-Met. Ltd.,

>99.85%, 0.375 in. OD) in a 1:1:2 molar ratio in an Ar-filled glovebox. The tube was sealed in an arc-melter under argon,

placed in a fused-silica jacket, and heated at 973 K for 3 days. The reaction container was cooled slowly to 673 K at 10 K

h-1_{, and then quenched to room temperature. When the tantalum tube was opened in the Ar-filled glovebox, grey}

irregular-shaped crystals of BaAgBi were found in the product. Single crystals were mounted in 0.3 mm thin-walled

capillaries for diffraction experiments.

S3. Refinement

Space groups P31c, P31c, P63mc, P63/mmc, and P62c were allowed based on the observed systematic absences. Space

group P63/mmc was initially selected and confirmed by comparing the refinement results with the other four space

groups. The Ba, Ag, and Bi atoms were readily located from the E-map, and refined with anisotropic displacement

parameters. The reflection 124 was omitted from the refinement because of possible interference from the beam stop of

the X-ray diffractometer. The largest residuals in the final difference map were 2.76 e Å-3 _{at a distance of 0.74 Å from Bi,}

Figure 1

The layer structure of BaAgBi along the z axis. Displacement ellipsoids are drawn at the 99% probability level. Key: Ba

grey, Ag blue, Bi red.

(I)

Crystal data

AgBaBi

Mr = 454.19

Hexagonal, P63/mmc Hall symbol: -P 6c 2c

a = 4.9423 (7) Å

c = 9.1251 (18) Å

V = 193.03 (5) Å3

Z = 2

F(000) = 372

Dx = 7.814 Mg m−3

Mo Kα radiation, λ = 0.71073 Å Cell parameters from 27 reflections

θ = 6.5–14.4°

µ = 60.31 mm−1

T = 293 K Irregular, grey

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Data collection

Rigaku AFC-6R diffractometer 2θ/ω scans

Absorption correction: ψ scan (North et al., 1968)

Tmin = 0.132, Tmax = 0.164 133 measured reflections 133 independent reflections

89 reflections with I > 2σ(I)

Rint = 0

θmax = 30.0°, θmin = 4.5°

h = 0→6

k = 0→3

l = 0→12

3 standard reflections every 100 reflections intensity decay: 0.9%

Refinement

Refinement on F2 Least-squares matrix: full

R[F2 _{> 2σ(F}2_{)] = 0.038}

wR(F2_{) = 0.102}

S = 1.16 133 reflections 8 parameters 0 restraints

w = 1/[σ2_(F

o2) + (0.0405P)2 + 2.2564P] where P = (Fo2 + 2Fc2)/3

(Δ/σ)max < 0.001 Δρmax = 2.76 e Å−3 Δρmin = −3.98 e Å−3

Extinction correction: SHELXL, Fc*_{=kFc[1+0.001xFc}2_λ3_/sin(2θ)]-1/4 Extinction coefficient: 0.011 (2)

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2₎

x y z Uiso*/Ueq

Ba 0 0 0 0.0094 (7)

Ag 0.3333 0.6667 0.25 0.0157 (9)

Bi 0.3333 0.6667 0.75 0.0091 (7)

Atomic displacement parameters (Å2₎

U11 _U22 _U33 _U12 _U13 _U23

Ba 0.0113 (10) 0.0113 (10) 0.0057 (12) 0.0057 (5) 0 0 Ag 0.0120 (11) 0.0120 (11) 0.0231 (18) 0.0060 (6) 0 0

Bi 0.0066 (7) 0.0066 (7) 0.0140 (10) 0.0033 (4) 0 0

Geometric parameters (Å, º)

Ba—Bii _{3.6533 (4) Ag—Ba}xiii _{3.6533 (4)}

Ba—Ag 3.6533 (4) Ag—Baxiv _{3.6533 (4)}

Ba—Biii _{3.6533 (4) Ag—Ba}xv _{3.6533 (4)}

Ba—Agiii _{3.6533 (4) Ag—Ba}xvi _{3.6533 (4)}

Ba—Biiv _{3.6533 (4) Ag—Ba}xvii _{3.6533 (4)}

Ba—Agv _{3.6533 (4) Bi—Ag}xii _{2.8534 (4)}

Ba—Bivi _{3.6533 (4) Bi—Ag}iv _{2.8534 (4)}

Ba—Agvii _{3.6533 (4) Bi—Ag}i _{2.8534 (4)}

Ba—Biix _{3.6533 (4) Bi—Ba}xvi _{3.6533 (4)}

Ba—Agx _{3.6533 (4) Bi—Ba}xv _{3.6533 (4)}

Ba—Bixi _{3.6533 (4) Bi—Ba}xix _{3.6533 (4)}

Ag—Bixii _{2.8534 (4) Bi—Ba}xx _{3.6533 (4)}

Ag—Biiv _{2.8534 (4) Bi—Ba}xiii _{3.6533 (4)}

Ag—Bii _{2.8534 (4)}

Bii_{—Ba—Ag 45.975 (5) Bi}xii_{—Ag—Ba 141.358 (7)}

Bii_—Ba—Biii _{180 Bi}iv_{—Ag—Ba 67.012 (2)}

Ag—Ba—Biii _{134.025 (5) Bi}i_{—Ag—Ba 67.012 (2)}

Bii_—Ba—Agiii _{134.025 (5) Bi}xii_—Ag—Baxiii _{67.012 (2)}

Ag—Ba—Agiii _{180 Bi}iv_—Ag—Baxiii _{141.358 (7)}

Biii_—Ba—Agiii _{45.975 (5) Bi}i_—Ag—Baxiii _{67.012 (2)} Bii_—Ba—Biiv _{85.129 (10) Ba—Ag—Ba}xiii _{134.025 (5)} Ag—Ba—Biiv _{45.975 (5) Bi}xii_—Ag—Baxiv _{67.012 (2)} Biii_—Ba—Biiv _{94.871 (10) Bi}iv_—Ag—Baxiv _{67.012 (2)} Agiii_—Ba—Biiv _{134.025 (5) Bi}i_—Ag—Baxiv _{141.358 (7)}

Bii_—Ba—Agv _{45.975 (5) Ba—Ag—Ba}xiv _{85.129 (10)}

Ag—Ba—Agv _{85.129 (10) Ba}xiii_—Ag—Baxiv _{134.025 (5)} Biii_—Ba—Agv _{134.025 (5) Bi}xii_—Ag—Baxv _{67.012 (2)} Agiii_—Ba—Agv _{94.871 (10) Bi}iv_—Ag—Baxv _{67.012 (2)} Biiv_—Ba—Agv _{102.717 (14) Bi}i_—Ag—Baxv _{141.358 (7)}

Bii_—Ba—Bivi _{94.871 (10) Ba—Ag—Ba}xv _{134.025 (5)}

Ag—Ba—Bivi _{134.025 (5) Ba}xiii_—Ag—Baxv _{85.129 (10)} Biii_—Ba—Bivi _{85.129 (10) Ba}xiv_—Ag—Baxv _{77.283 (14)} Agiii_—Ba—Bivi _{45.975 (5) Bi}xii_—Ag—Baxvi _{141.358 (7)}

Biiv_—Ba—Bivi _{180 Bi}iv_—Ag—Baxvi _{67.012 (2)}

Agv_—Ba—Bivi _{77.283 (14) Bi}i_—Ag—Baxvi _{67.012 (2)} Bii_—Ba—Agvii _{134.025 (5) Ba—Ag—Ba}xvi _{77.283 (14)} Ag—Ba—Agvii _{94.871 (10) Ba}xiii_—Ag—Baxvi _{85.129 (10)} Biii_—Ba—Agvii _{45.975 (5) Ba}xiv_—Ag—Baxvi _{134.025 (5)} Agiii_—Ba—Agvii _{85.129 (10) Ba}xv_—Ag—Baxvi _{85.129 (10)} Biiv_—Ba—Agvii _{77.283 (14) Bi}xii_—Ag—Baxvii _{67.012 (2)}

Agv_—Ba—Agvii _{180 Bi}iv_—Ag—Baxvii _{141.358 (7)}

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Agv_—Ba—Biix _{45.975 (5) Ag}i_—Bi—Baxvi _{67.012 (2)} Bivi_—Ba—Biix _{94.871 (10) Ba}xviii_—Bi—Baxvi _{134.025 (5)} Agvii_—Ba—Biix _{134.025 (5) Ag}xii_—Bi—Baxv _{67.012 (2)} Agviii_—Ba—Biix _{45.975 (5) Ag}iv_—Bi—Baxv _{67.012 (2)} Bii_—Ba—Agx _{77.283 (14) Ag}i_—Bi—Baxv _{141.358 (7)} Ag—Ba—Agx _{94.871 (10) Ba}xviii_—Bi—Baxv _{134.025 (5)} Biii_—Ba—Agx _{102.717 (14) Ba}xvi_—Bi—Baxv _{85.129 (10)} Agiii_—Ba—Agx _{85.129 (10) Ag}xii_—Bi—Baxix _{67.012 (2)} Biiv_—Ba—Agx _{134.025 (5) Ag}iv_—Bi—Baxix _{67.012 (2)} Agv_—Ba—Agx _{94.871 (10) Ag}i_—Bi—Baxix _{141.358 (7)} Bivi_—Ba—Agx _{45.975 (5) Ba}xviii_—Bi—Baxix _{85.129 (10)} Agvii_—Ba—Agx _{85.129 (10) Ba}xvi_—Bi—Baxix _{134.025 (5)}

Agviii_—Ba—Agx _{180 Ba}xv_—Bi—Baxix _{77.283 (14)}

Biix_—Ba—Agx _{134.025 (5) Ag}xii_—Bi—Baxx _{141.358 (7)} Bii_—Ba—Bixi _{94.871 (10) Ag}iv_—Bi—Baxx _{67.012 (2)}

Ag—Ba—Bixi _{77.283 (14) Ag}i_—Bi—Baxx _{67.012 (2)}

Biii_—Ba—Bixi _{85.129 (10) Ba}xviii_—Bi—Baxx _{85.129 (10)} Agiii_—Ba—Bixi _{102.717 (14) Ba}xvi_—Bi—Baxx _{77.283 (14)} Biiv_—Ba—Bixi _{94.871 (10) Ba}xv_—Bi—Baxx _{134.025 (5)} Agv_—Ba—Bixi _{134.025 (5) Ba}xix_—Bi—Baxx _{85.129 (10)} Bivi_—Ba—Bixi _{85.129 (10) Ag}xii_—Bi—Baxiii _{67.012 (2)} Agvii_—Ba—Bixi _{45.975 (5) Ag}iv_—Bi—Baxiii _{141.358 (7)} Agviii_—Ba—Bixi _{134.025 (5) Ag}i_—Bi—Baxiii _{67.012 (2)} Biix_—Ba—Bixi _{180 Ba}xviii_—Bi—Baxiii _{77.283 (14)} Agx_—Ba—Bixi _{45.975 (5) Ba}xvi_—Bi—Baxiii _{85.129 (10)}

Bixii_—Ag—Biiv _{120 Ba}xv_—Bi—Baxiii _{85.129 (10)}

Bixii_—Ag—Bii _{120 Ba}xix_—Bi—Baxiii _{134.025 (5)}

Biiv_—Ag—Bii _{120 Ba}xx_—Bi—Baxiii _{134.025 (5)}

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x−1, y−1, z−1; (iii) −x, −y, −z; (iv) −x, −y+1, −z+1; (v) x, y−1, z; (vi) x, y−1, z−1; (vii) −x, −y+1, −z; (viii) x−1,