Search tips
Search criteria 


Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
Acta Crystallogr Sect E Struct Rep Online. 2009 December 1; 65(Pt 12): i90.
Published online 2009 November 21. doi:  10.1107/S1600536809048454
PMCID: PMC2971942

Non-isovalent substitution in a Zintl phase with the TiNiSi type structure, CaMg1–xAgxGe [x = 0.13 (3)]


Single crystals of the title Ag-substituted calcium magnesium germanide, CaMg1–xAgxGe [x = 0.13 (3)] were obtained from the reaction of the corresponding elements at high temperature. The compound crystallizes with the TiNiSi structure type (Pearson code oP12) and represents an Ag-substituted derivative of the Zintl phase CaMgGe in which a small fraction of the divalent Mg atoms have been replaced by monovalent Ag atoms. All three atoms in the asymmetric unit (Ca, Mg/Ag, Ge) occupy special positions with the same site symmetry (.m.). Although the end member CaAgGe has been reported in an isomorphic superstructure of the same TiNiSi type, higher Ag content in solid solutions could not be achieved due to competitive formation of other, perhaps more stable, phases.

Related literature

For the KHg2 structure type, see: Duwell & Baenziger (1955 [triangle]) and for the TiNiSi structure type, see: Shoemaker & Shoemaker (1965 [triangle]); Eisenmann et al. (1972 [triangle]); Villars & Calvert (1991 [triangle]). For the structural systematics and properties of the TiNiSi structure type, see: Kauzlarich (1996 [triangle]); Landrum et al. (1998 [triangle]). For related compounds, see: Ponou & Lidin (2008 [triangle]); Ponou et al. (2007 [triangle]). For atomic radii, see: Pauling (1960 [triangle]).


Crystal data

  • CaMg0.87Ag0.13Ge
  • M r = 147.84
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-65-00i90-efi1.jpg
  • a = 7.5128 (2) Å
  • b = 4.4573 (1) Å
  • c = 8.3911 (2) Å
  • V = 280.99 (1) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 13.43 mm−1
  • T = 293 K
  • 0.10 × 0.06 × 0.04 mm

Data collection

  • Oxford Xcalibur3 diffractometer
  • Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007 [triangle]) T min = 0.396, T max = 0.584
  • 2462 measured reflections
  • 516 independent reflections
  • 481 reflections with I > 2σ(I)
  • R int = 0.026


  • R[F 2 > 2σ(F 2)] = 0.019
  • wR(F 2) = 0.041
  • S = 1.10
  • 516 reflections
  • 21 parameters
  • Δρmax = 0.89 e Å−3
  • Δρmin = −0.44 e Å−3

Data collection: CrysAlis CCD (Oxford Diffraction, 2007 [triangle]); cell refinement: CrysAlis RED (Oxford Diffraction, 2007 [triangle]); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: DIAMOND (Brandenburg, 1999 [triangle]); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 [triangle]).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809048454/hb5206sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809048454/hb5206Isup2.hkl

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


Financial support from the Wenner-Gren Foundation in gratefully acknowledged. The authors thank Professor Sven Lidin (Stockholm University, Sweden) for continuous support.

supplementary crystallographic information


The solid solution CaMg1–xAgxGe [x = 0.13 (3)] is iso-structural with the non-substituted ternary phase CaMgGe (Eisenmann et al., 1972). It crystallizes in the TiNiSi type (Space Group Pnma) with Ca, Mg/Ag, and Ge at Ti, Ni, and Si-positions, respectively. The TiNiSi type (Shoemaker & Shoemaker, 1965) which is well represented among ternary equiatomic phases (Villars & Calvert, 1991), is an ordered ternary derivative of the KHg2 type (Duwell & Baenziger, 1955; Pearson code oI12). Hence, the structure consist of a three-dimensional four-connected anionic [Mg1–xAgxGe] networks with the Ca cations sitting in large channels (Fig. 1). The anionic network may be constructed from two-dimensional sheets, similar to those in black phosphorus and running perpendicular to the a-axis, which are linked along the a-direction to form one-dimensional ladders of edge-sharing four-rings and channels of eight-rings running along the b-direction. The TiNiSi type is known to be very versatile and shows remarkable structural and electronic flexibility (Landrum et al., 1998). Meanwhile, a large number of compounds with the TiNiSi type like CaMgGe can be rationalized as Zintl phases (Kauzlarich, 1996) according to the ionic formulation Ca2+(Mg2+Ge4–). Zinlt phases are known to be very sensitive to the electron count (Ponou et al., 2007). But, because of the above mentioned flexibility of the TiNiSi type, non-isovalent substitutions was expected without major structural distortion. Thus, since CaAgGe crystallizes in the isomorphic (i3) superstructure of the TiNiSi type with a tripling of the a-axis (Ponou & Lidin, 2008), a wide stoichiometry breadth was expected in the system CaMg1–xAgxGe. Eventually, the reaction of different starting mixtures with x = 1/4, 1/2, and 3/4, yielded almost the same composition (x = 0.10 – 0.13) within 3σ standard deviation. This indicates a narrow homogeneity range, meaning that in this class of materials, the inherent electronic rigidity of the Zintl phase may be conflicting with the otherwise remarkable flexibility of TiNiSi type.

CaMg0.87 (1)Ag0.13 (1)Ge is the Ag-richest phase that was structurally characterized. The unit-cell volume here (V = 280.99 (1) Å3) is quite similar to that of the non-substituted phase CaMgGe (V = 280.89 Å3), though the size of Mg is significantly larger than [Pauling's (1960) radii: Mg 1.600 Å, Ag 1.440 Å]. But, it should be noted that the later cell parameters were determined with much higher standard deviation (Eisenmann et al., 1972). In a reinvestigation of the CaMgGe structure (not reported), no indications of any superstructure were found.


Three different mixtures of the elements (all from ABCR GmbH, Karlsruhe, Germany) Ca (granule, 99.5%), Mg (pieces, 99.9%), Ag (60m powder, 99.9%), and Ge (50m powder, 99.999%), with compositions along the CaMg1–xAgxGe series with x = 1/4, 1/2, and 0.75 were loaded in a Niobium ampoules (approx. 9 mm diameter and 30 mm length) which were sealed on both ends by arc-melting and, in turn, enclosed in evacuated fused silica Schlenk tube to protect the former from air oxidation at high temperature. The ampoules were heated at 1273 K for 2 h, and cooled at a rate of 6 K/h to 923 K, where they are annealed for 24 h, then cooled down to room temperature by turning off the furnace. Semi quantitative EDX analysis of the single crystals confirmed the presenced of the four elements, and no eventual contaminant at the detection limit could be observed.


The refinement was straightforward, the full occupancies for all sites were verified by freeing the site occupation factor for an individual atom, while keeping that of the other atoms fixed. This proved that all positions but one, the Mg site, were fully occupied. The refined occupancy at Mg assigned position was higher than 100%, indicating a mixing with heavier element. Therefore, this position (labelled Mg/Ag) was modelled as a statistical mixture of Mg and Ag, and refined as 86.9 (1)% Mg and 13.1 (1)% Ag.


Fig. 1.
: A perspective view of (I) with displacement ellipsoids drawn at 95% probability level. Ca, Mg/Ag, and Ge atoms are drawn as grey crossed, orange and blue spheres, respectively.

Crystal data

CaMg0.87Ag0.13GeF(000) = 273.5
Mr = 147.84Dx = 3.495 Mg m3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 2462 reflections
a = 7.5128 (2) Åθ = 4.9–32.1°
b = 4.4573 (1) ŵ = 13.43 mm1
c = 8.3911 (2) ÅT = 293 K
V = 280.99 (1) Å3Irregular block, grey
Z = 40.10 × 0.06 × 0.04 mm

Data collection

Oxford Xcalibur3 diffractometer516 independent reflections
Radiation source: Enhance (Mo) X-ray Source481 reflections with I > 2σ(I)
graphiteRint = 0.026
Detector resolution: 16.5467 pixels mm-1θmax = 32.1°, θmin = 4.6°
ω scansh = −8→10
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007)k = −5→6
Tmin = 0.396, Tmax = 0.584l = −12→12
2462 measured reflections


Refinement on F20 restraints
Least-squares matrix: fullw = 1/[σ2(Fo2) + (0.0233P)2] where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.019(Δ/σ)max < 0.001
wR(F2) = 0.041Δρmax = 0.89 e Å3
S = 1.10Δρmin = −0.44 e Å3
516 reflectionsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
21 parametersExtinction coefficient: 0.084 (3)

Special details

Experimental. CrysAlis RED, (Oxford Diffraction, 2007) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.
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)

xyzUiso*/UeqOcc. (<1)
Ge10.76875 (4)0.25000.38457 (3)0.00994 (12)
Ag10.14396 (8)0.25000.43738 (7)0.0140 (2)0.1309 (15)
Mg10.14396 (8)0.25000.43738 (7)0.0140 (2)0.8691 (15)
Ca10.51982 (7)0.25000.68206 (7)0.01280 (14)

Atomic displacement parameters (Å2)

Ge10.00976 (16)0.00827 (16)0.01178 (17)0.000−0.00007 (9)0.000
Ag10.0172 (4)0.0124 (3)0.0124 (3)0.000−0.0020 (2)0.000
Mg10.0172 (4)0.0124 (3)0.0124 (3)0.000−0.0020 (2)0.000
Ca10.0119 (3)0.0134 (3)0.0131 (3)0.000−0.00085 (18)0.000

Geometric parameters (Å, °)

Ge1—Mg1i2.7621 (4)Ag1—Ag1viii3.2788 (9)
Ge1—Ag1i2.7621 (4)Ag1—Mg1ix3.2788 (9)
Ge1—Mg1ii2.7621 (4)Ag1—Ag1ix3.2788 (9)
Ge1—Ag1ii2.7621 (4)Ag1—Ca1x3.3267 (8)
Ge1—Ag1iii2.8535 (7)Ag1—Ca1xi3.3273 (6)
Ge1—Mg1iii2.8535 (7)Ag1—Ca1xii3.3273 (6)
Ge1—Mg1iv2.8596 (7)Ag1—Ca13.4912 (8)
Ge1—Ag1iv2.8596 (7)Ca1—Ge1ii3.1590 (4)
Ge1—Ca13.1191 (6)Ca1—Ge1i3.1590 (4)
Ge1—Ca1ii3.1590 (4)Ca1—Ge1xiii3.2214 (4)
Ge1—Ca1i3.1590 (4)Ca1—Ge1xiv3.2214 (4)
Ge1—Ca1v3.2214 (4)Ca1—Mg1xv3.3267 (8)
Ag1—Ge1i2.7621 (4)Ca1—Ag1xv3.3267 (8)
Ag1—Ge1ii2.7621 (4)Ca1—Mg1xvi3.3273 (6)
Ag1—Ge1vi2.8535 (7)Ca1—Ag1xvi3.3273 (6)
Ag1—Ge1vii2.8596 (7)Ca1—Mg1xvii3.3273 (6)
Ag1—Mg1viii3.2788 (9)Ca1—Ag1xvii3.3273 (6)
Mg1i—Ge1—Ag1i0.00 (2)Ge1i—Ag1—Ca1x63.086 (14)
Mg1i—Ge1—Mg1ii107.58 (2)Ge1ii—Ag1—Ca1x63.086 (14)
Ag1i—Ge1—Mg1ii107.58 (2)Ge1vi—Ag1—Ca1x82.653 (19)
Mg1i—Ge1—Ag1ii107.58 (2)Ge1vii—Ag1—Ca1x177.14 (3)
Ag1i—Ge1—Ag1ii107.58 (2)Mg1viii—Ag1—Ca1x60.49 (2)
Mg1ii—Ge1—Ag1ii0.0Ag1viii—Ag1—Ca1x60.49 (2)
Mg1i—Ge1—Ag1iii71.425 (16)Mg1ix—Ag1—Ca1x60.49 (2)
Ag1i—Ge1—Ag1iii71.425 (16)Ag1ix—Ag1—Ca1x60.49 (2)
Mg1ii—Ge1—Ag1iii71.425 (16)Ge1i—Ag1—Ca1xi167.565 (19)
Ag1ii—Ge1—Ag1iii71.425 (16)Ge1ii—Ag1—Ca1xi84.010 (9)
Mg1i—Ge1—Mg1iii71.425 (16)Ge1vi—Ag1—Ca1xi62.269 (13)
Ag1i—Ge1—Mg1iii71.425 (16)Ge1vii—Ag1—Ca1xi60.851 (14)
Mg1ii—Ge1—Mg1iii71.425 (16)Mg1viii—Ag1—Ca1xi60.470 (16)
Ag1ii—Ge1—Mg1iii71.425 (16)Ag1viii—Ag1—Ca1xi60.470 (16)
Ag1iii—Ge1—Mg1iii0.00 (2)Mg1ix—Ag1—Ca1xi114.69 (3)
Mg1i—Ge1—Mg1iv126.076 (12)Ag1ix—Ag1—Ca1xi114.69 (3)
Ag1i—Ge1—Mg1iv126.076 (12)Ca1x—Ag1—Ca1xi120.958 (16)
Mg1ii—Ge1—Mg1iv126.075 (12)Ge1i—Ag1—Ca1xii84.010 (9)
Ag1ii—Ge1—Mg1iv126.075 (12)Ge1ii—Ag1—Ca1xii167.565 (19)
Ag1iii—Ge1—Mg1iv118.073 (19)Ge1vi—Ag1—Ca1xii62.269 (13)
Mg1iii—Ge1—Mg1iv118.073 (19)Ge1vii—Ag1—Ca1xii60.851 (14)
Mg1i—Ge1—Ag1iv126.076 (12)Mg1viii—Ag1—Ca1xii114.69 (3)
Ag1i—Ge1—Ag1iv126.076 (12)Ag1viii—Ag1—Ca1xii114.69 (3)
Mg1ii—Ge1—Ag1iv126.075 (12)Mg1ix—Ag1—Ca1xii60.470 (16)
Ag1ii—Ge1—Ag1iv126.075 (12)Ag1ix—Ag1—Ca1xii60.470 (16)
Ag1iii—Ge1—Ag1iv118.073 (19)Ca1x—Ag1—Ca1xii120.958 (16)
Mg1iii—Ge1—Ag1iv118.073 (19)Ca1xi—Ag1—Ca1xii84.104 (19)
Mg1iv—Ge1—Ag1iv0.00 (2)Ge1i—Ag1—Ca159.328 (12)
Mg1i—Ge1—Ca173.110 (14)Ge1ii—Ag1—Ca159.328 (12)
Ag1i—Ge1—Ca173.110 (14)Ge1vi—Ag1—Ca1152.91 (2)
Mg1ii—Ge1—Ca173.110 (14)Ge1vii—Ag1—Ca1106.88 (2)
Ag1ii—Ge1—Ca173.110 (14)Mg1viii—Ag1—Ca1110.19 (2)
Ag1iii—Ge1—Ca1117.905 (19)Ag1viii—Ag1—Ca1110.19 (2)
Mg1iii—Ge1—Ca1117.905 (19)Mg1ix—Ag1—Ca1110.19 (2)
Mg1iv—Ge1—Ca1124.022 (18)Ag1ix—Ag1—Ca1110.19 (2)
Ag1iv—Ge1—Ca1124.022 (18)Ca1x—Ag1—Ca170.261 (14)
Mg1i—Ge1—Ca1ii145.884 (18)Ca1xi—Ag1—Ca1132.669 (11)
Ag1i—Ge1—Ca1ii145.884 (18)Ca1xii—Ag1—Ca1132.669 (11)
Mg1ii—Ge1—Ca1ii71.906 (14)Ge1—Ca1—Ge1ii105.655 (14)
Ag1ii—Ge1—Ca1ii71.906 (14)Ge1—Ca1—Ge1i105.655 (14)
Ag1iii—Ge1—Ca1ii134.864 (8)Ge1ii—Ca1—Ge1i89.738 (15)
Mg1iii—Ge1—Ca1ii134.864 (8)Ge1—Ca1—Ge1xiii97.268 (13)
Mg1iv—Ge1—Ca1ii66.910 (14)Ge1ii—Ca1—Ge1xiii156.90 (2)
Ag1iv—Ge1—Ca1ii66.910 (14)Ge1i—Ca1—Ge1xiii86.771 (6)
Ca1—Ge1—Ca1ii74.345 (14)Ge1—Ca1—Ge1xiv97.268 (13)
Mg1i—Ge1—Ca1i71.906 (14)Ge1ii—Ca1—Ge1xiv86.771 (6)
Ag1i—Ge1—Ca1i71.906 (14)Ge1i—Ca1—Ge1xiv156.90 (2)
Mg1ii—Ge1—Ca1i145.884 (18)Ge1xiii—Ca1—Ge1xiv87.548 (14)
Ag1ii—Ge1—Ca1i145.884 (18)Ge1—Ca1—Mg1xv126.88 (2)
Ag1iii—Ge1—Ca1i134.864 (8)Ge1ii—Ca1—Mg1xv111.240 (16)
Mg1iii—Ge1—Ca1i134.864 (8)Ge1i—Ca1—Mg1xv111.240 (16)
Mg1iv—Ge1—Ca1i66.910 (14)Ge1xiii—Ca1—Mg1xv49.866 (10)
Ag1iv—Ge1—Ca1i66.910 (14)Ge1xiv—Ca1—Mg1xv49.866 (10)
Ca1—Ge1—Ca1i74.345 (14)Ge1—Ca1—Ag1xv126.88 (2)
Ca1ii—Ge1—Ca1i89.738 (15)Ge1ii—Ca1—Ag1xv111.240 (16)
Mg1i—Ge1—Ca1v136.591 (17)Ge1i—Ca1—Ag1xv111.240 (16)
Ag1i—Ge1—Ca1v136.591 (17)Ge1xiii—Ca1—Ag1xv49.866 (10)
Mg1ii—Ge1—Ca1v67.048 (15)Ge1xiv—Ca1—Ag1xv49.866 (10)
Ag1ii—Ge1—Ca1v67.048 (15)Mg1xv—Ca1—Ag1xv0.000 (6)
Ag1iii—Ge1—Ca1v66.097 (13)Ge1—Ca1—Mg1xvi137.481 (10)
Mg1iii—Ge1—Ca1v66.097 (13)Ge1ii—Ca1—Mg1xvi109.433 (18)
Mg1iv—Ge1—Ca1v70.325 (14)Ge1i—Ca1—Mg1xvi52.239 (12)
Ag1iv—Ge1—Ca1v70.325 (14)Ge1xiii—Ca1—Mg1xvi51.633 (12)
Ca1—Ge1—Ca1v135.874 (8)Ge1xiv—Ca1—Mg1xvi107.823 (18)
Ca1ii—Ge1—Ca1v75.935 (6)Mg1xv—Ca1—Mg1xvi59.042 (16)
Ca1i—Ge1—Ca1v137.148 (11)Ag1xv—Ca1—Mg1xvi59.042 (16)
Ge1i—Ag1—Ge1ii107.58 (2)Ge1—Ca1—Ag1xvi137.481 (10)
Ge1i—Ag1—Ge1vi108.575 (16)Ge1ii—Ca1—Ag1xvi109.433 (18)
Ge1ii—Ag1—Ge1vi108.575 (16)Ge1i—Ca1—Ag1xvi52.239 (12)
Ge1i—Ag1—Ge1vii115.669 (14)Ge1xiii—Ca1—Ag1xvi51.633 (12)
Ge1ii—Ag1—Ge1vii115.669 (14)Ge1xiv—Ca1—Ag1xvi107.823 (18)
Ge1vi—Ag1—Ge1vii100.20 (2)Mg1xv—Ca1—Ag1xvi59.042 (16)
Ge1i—Ag1—Mg1viii122.12 (3)Ag1xv—Ca1—Ag1xvi59.042 (16)
Ge1ii—Ag1—Mg1viii55.586 (12)Mg1xvi—Ca1—Ag1xvi0.00 (3)
Ge1vi—Ag1—Mg1viii52.990 (18)Ge1—Ca1—Mg1xvii137.481 (10)
Ge1vii—Ag1—Mg1viii121.27 (2)Ge1ii—Ca1—Mg1xvii52.239 (12)
Ge1i—Ag1—Ag1viii122.12 (3)Ge1i—Ca1—Mg1xvii109.433 (18)
Ge1ii—Ag1—Ag1viii55.586 (12)Ge1xiii—Ca1—Mg1xvii107.823 (18)
Ge1vi—Ag1—Ag1viii52.990 (18)Ge1xiv—Ca1—Mg1xvii51.633 (12)
Ge1vii—Ag1—Ag1viii121.27 (2)Mg1xv—Ca1—Mg1xvii59.042 (16)
Mg1viii—Ag1—Ag1viii0.000 (16)Ag1xv—Ca1—Mg1xvii59.042 (16)
Ge1i—Ag1—Mg1ix55.586 (12)Mg1xvi—Ca1—Mg1xvii84.104 (19)
Ge1ii—Ag1—Mg1ix122.12 (3)Ag1xvi—Ca1—Mg1xvii84.104 (19)
Ge1vi—Ag1—Mg1ix52.990 (18)Ge1—Ca1—Ag1xvii137.481 (10)
Ge1vii—Ag1—Mg1ix121.27 (2)Ge1ii—Ca1—Ag1xvii52.239 (12)
Mg1viii—Ag1—Mg1ix85.64 (3)Ge1i—Ca1—Ag1xvii109.433 (18)
Ag1viii—Ag1—Mg1ix85.64 (3)Ge1xiii—Ca1—Ag1xvii107.823 (18)
Ge1i—Ag1—Ag1ix55.586 (12)Ge1xiv—Ca1—Ag1xvii51.633 (12)
Ge1ii—Ag1—Ag1ix122.12 (3)Mg1xv—Ca1—Ag1xvii59.042 (16)
Ge1vi—Ag1—Ag1ix52.990 (18)Ag1xv—Ca1—Ag1xvii59.042 (16)
Ge1vii—Ag1—Ag1ix121.27 (2)Mg1xvi—Ca1—Ag1xvii84.104 (19)
Mg1viii—Ag1—Ag1ix85.64 (3)Ag1xvi—Ca1—Ag1xvii84.104 (19)
Ag1viii—Ag1—Ag1ix85.64 (3)Mg1xvii—Ca1—Ag1xvii0.00 (2)
Mg1ix—Ag1—Ag1ix0.000 (16)

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+1, −y, −z+1; (iii) x+1, y, z; (iv) x+1/2, y, −z+1/2; (v) −x+3/2, −y, z−1/2; (vi) x−1, y, z; (vii) x−1/2, y, −z+1/2; (viii) −x, −y, −z+1; (ix) −x, −y+1, −z+1; (x) x−1/2, y, −z+3/2; (xi) −x+1/2, −y, z−1/2; (xii) −x+1/2, −y+1, z−1/2; (xiii) −x+3/2, −y+1, z+1/2; (xiv) −x+3/2, −y, z+1/2; (xv) x+1/2, y, −z+3/2; (xvi) −x+1/2, −y+1, z+1/2; (xvii) −x+1/2, −y, z+1/2.


Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB5206).


  • Brandenburg, K. (1999). DIAMOND. Crystal Impact, Bonn, Germany.
  • Duwell, E. J. & Baenziger, N. C. (1955). Acta Cryst. 8, 705–710.
  • Eisenmann, B., Schaefer, H. & Weiss, A. (1972). Z. Anorg. Allg. Chem. 391, 241–254.
  • Kauzlarich, S. M. (1996). Chemistry, Structure and Bonding in Zintl Phases and Ions. New York: VCH.
  • Landrum, G. A., Hoffmann, R., Evers, J. & Boysen, H. (1998). Inorg. Chem 37, 5754–5763.
  • Oxford Diffraction (2007). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.
  • Pauling, L. (1960). The Nature of the Chemical Bond, 3rd ed. Ithaca, NY: Cornell University Press.
  • Ponou, S., Kim, S. J. & Fässler, T. F. (2007). Z. Anorg. Allg. Chem. 633, 1568–1574.
  • Ponou, S. & Lidin, S. (2008). Z. Kristallogr. New Cryst. Struct. 223, 329–330.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Shoemaker, C. B. & Shoemaker, D. P. (1965). Acta Cryst. 18, 900–905.
  • Villars, P. & Calvert, L. D. (1991). Pearson’s Handbook of Crystallographic Data for Intermetallic Coumpounds, 2nd ed. OH, USA: ASM International.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography