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The structure of potassium yttrium hexaniobium octadeca­chloride is built of anionic [Nb6Cl12iCl6a]4- cluster units (where `i' and `a' denote inner and outer ligands, respectively), linked together by K+ and Y3+ cations. The K+ cations occupy half of the tetrahedral vacancies in the face-centered cubic lattice of cluster units, and are coordinated by 12 chloride ligands. The Y atom is located in an octahedral site and is bonded to six outer chloride ligands.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103003731/bc1007sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270103003731/bc1007Isup2.hkl
Contains datablock I

Comment top

A large number of metal-rich niobium chlorides with [Nb6Cl18]n--type cluster units have been previously crystallized using a variety of metal cations, for instance, the two series ARENb6Cl18 (where A is an alkali and RE is a rare earth element; Ihmaine et al., 1987, 1988, 1989) and ATiNb6Cl18 (where A is an alkali or group 13 element; Nagele et al., 2000), and the recently prepared cluster compounds Cs2PbNb6Cl18 (Gulo et al., 2001) and K2SrNb6Cl18 (Duraisamy & Lachgar, 2002), which contain Pb2+ and Sr2+, respectively. For the series ARENb6Cl18, the crystal structures of compounds with RE = Gd3+ (Ihmaine et al., 1987) and Lu3+ (Ihmaine et al., 1988, 1989) have been reported, while compounds with other rare-earth metal cations are still unknown.

In the present paper, we report the crystal structure of potassium yttrium hexaniobium octadecachloride, KYNb6Cl18. The title compound crystallizes in trigonal space group R3. The structure is based on discrete anionic cluster units, [Nb6Cli12Cla6]4− (where `i' and `a' denote `inner' and `outer' ligands, respectively). The anionic cluster unit consists of an Nb6 octahedron in which all edges are bridged by chloride ligands, and six other ligands are in apical positions (Fig. 1). The intra-cluster bond lengths, Nb—Nb = 2.9143 (6)–2.9182 (6), Nb—Cli = 2.4476 (10)–2.4556 (10) and Nb—Cla = 2.6497 (10) Å are typical for [Nb6Cl18]4− clusters. The Nb—Nb bond length indicates that the VEC (valence electrons per cluster) is 16. The three-dimensional structure of the title compound is based on the cluster units interlinked to each other by K+ and Y3+ cations (Fig. 2). The cluster layers are arranged according to a face-centered cubic stacking along the c axis. The K+ ions occupy tetrahedral vacancies between the units and are coordinated -to 12 Cl ligands, with K—Cl distances in the range 3.4520 (11)–3.5292 (10) Å. The yttrium ions are located in octahedral sites between the units and are bonded to six Cl ligands from six different units in a regular octahedral geometry, with Y—Cl distances of 2.6414 (10) Å. Only half of the tetrahedral sites are occupied by K in the title compound, in contrast to to situation in both Cs2PbNb6Cl18 (Gulo et al., 2001) and K2SrNb6Cl18 (Duraisamy & Lachgar, 2002) where the alkali metal site is fully occupied.

Experimental top

The title compound, KYNb6Cl18, was initially obtained as shiny black cuboctahedral crystals from a reaction proposed to yield an oxychloride compound of the composition K2Y2Nb6Cl14O5. The compound was prepared quantitatively from a stoichiometric mixture containing NbCl5 (Alfa, 99.8%), Nb powder (Alfa 99.8%), YCl3 (Alfa 99.9%), and KCl (Alfa, 99.99%). The mixture was handled under an argon atmosphere and the reaction was performed in a sealed quartz tube at 1023 K over a period of 4 d. The heating and cooling ramps were 20 and 10 K h−1, respectively.

Computing details top

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: SHELXTL (Bruker, 1999); program(s) used to solve structure: SHELXTL; program(s) used to refine structure: SHELXTL.

Figures top
[Figure 1] Fig. 1. The chloride cluster anion, [Nb6Cli12Cla6]4−, present in KYNb6Cl18. The superscripts `i' and 1a' denote inner and outer ligands, respectively.
[Figure 2] Fig. 2. Projection of the crystal structure of KYNb6Cl18 in the [110] direction.
Potassium yttrium hexaniobium octadecachloride top
Crystal data top
KYNb6Cl18Dx = 3.500 Mg m3
Mr = 1323.57Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3Cell parameters from 38 reflections
Hall symbol: -R 3θ = 2.7–12.5°
a = 9.2527 (6) ŵ = 7.00 mm1
c = 25.410 (2) ÅT = 293 K
V = 1884.0 (2) Å3Truncated cuboctahedron, black
Z = 30.20 × 0.17 × 0.15 mm
F(000) = 1830
Data collection top
Bruker P4
diffractometer
1045 reflections with I > 2σ(I)
Radiation source: normal-focus sealed tubeRint = 0.028
Graphite monochromatorθmax = 31.0°, θmin = 2.4°
ω scansh = 113
Absorption correction: empirical (using intensity measurements)
via ψ scan (North et al., 1968)
k = 131
Tmin = 0.709, Tmax = 0.965l = 136
1803 measured reflections3 standard reflections every 297 reflections
1342 independent reflections intensity decay: none
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.032Secondary atom site location: difference Fourier map
wR(F2) = 0.050 w = 1/[σ2(Fo2) + (0.0137P)2 + 0.4236P]
where P = (Fo2 + 2Fc2)/3
S = 1.03(Δ/σ)max = 0.001
1342 reflectionsΔρmax = 0.77 e Å3
42 parametersΔρmin = 0.90 e Å3
Crystal data top
KYNb6Cl18Z = 3
Mr = 1323.57Mo Kα radiation
Trigonal, R3µ = 7.00 mm1
a = 9.2527 (6) ÅT = 293 K
c = 25.410 (2) Å0.20 × 0.17 × 0.15 mm
V = 1884.0 (2) Å3
Data collection top
Bruker P4
diffractometer
1045 reflections with I > 2σ(I)
Absorption correction: empirical (using intensity measurements)
via ψ scan (North et al., 1968)
Rint = 0.028
Tmin = 0.709, Tmax = 0.9653 standard reflections every 297 reflections
1803 measured reflections intensity decay: none
1342 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.03242 parameters
wR(F2) = 0.0500 restraints
S = 1.03Δρmax = 0.77 e Å3
1342 reflectionsΔρmin = 0.90 e Å3
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)
Nb0.04066 (4)0.15832 (4)0.046790 (12)0.00829 (7)
Cl10.08430 (13)0.36696 (13)0.10715 (4)0.01615 (19)
Cl20.18582 (12)0.23352 (12)0.11040 (3)0.01529 (18)
Cl30.27860 (13)0.14169 (13)0.00074 (4)0.01407 (18)
Y0.333330.333330.166670.01086 (17)
K0.333330.666670.11103 (19)0.0419 (11)0.50
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Nb0.00856 (15)0.00834 (16)0.00833 (11)0.00451 (13)0.00005 (13)0.00062 (13)
Cl10.0166 (5)0.0164 (4)0.0169 (4)0.0094 (4)0.0032 (4)0.0027 (4)
Cl20.0162 (5)0.0181 (5)0.0139 (4)0.0104 (4)0.0046 (4)0.0058 (4)
Cl30.0139 (4)0.0169 (5)0.0159 (3)0.0111 (4)0.0023 (4)0.0034 (3)
Y0.0111 (3)0.0111 (3)0.0103 (4)0.00556 (13)0.0000.000
K0.0420 (16)0.0420 (16)0.042 (2)0.0210 (8)0.0000.000
Geometric parameters (Å, º) top
Nb—Cl32.4476 (10)Y—Cl1vii2.6414 (10)
Nb—Cl3i2.4498 (10)Y—Cl1viii2.6414 (10)
Nb—Cl2ii2.4554 (10)Y—Cl1ix2.6414 (10)
Nb—Cl22.4556 (10)Y—Cl1x2.6414 (10)
Nb—Cl12.6497 (10)Y—Cl1xi2.6414 (10)
Nb—Nbi2.9143 (6)K—Cl1xii3.4520 (11)
Nb—Nbiii2.9142 (6)K—Cl1xiii3.4520 (11)
Nb—Nbii2.9182 (6)K—Cl2x3.463 (4)
Nb—Nbiv2.9182 (6)K—Cl2v3.464 (4)
Cl1—Y2.6414 (10)K—Cl2xiv3.464 (4)
Cl1—K3.4520 (11)K—Cl3vi3.486 (4)
Cl2—Nbiv2.4554 (10)K—Cl3xv3.486 (4)
Cl2—Kv3.464 (4)K—Cl3i3.486 (4)
Cl2—K3.5292 (10)K—Cl2xii3.5292 (10)
Cl3—Nbiii2.4498 (10)K—Cl2xiii3.5292 (10)
Cl3—Kvi3.486 (4)
Cl3—Nb—Cl3i88.818 (12)Cl1—K—Cl1xiii119.919 (8)
Cl3—Nb—Cl2ii89.67 (4)Cl1xii—K—Cl2x61.00 (4)
Cl3i—Nb—Cl2ii162.98 (4)Cl1—K—Cl2x93.03 (7)
Cl3—Nb—Cl2162.94 (3)Cl1xiii—K—Cl2x120.15 (11)
Cl3i—Nb—Cl288.05 (4)Cl1xii—K—Cl2v120.15 (11)
Cl2ii—Nb—Cl288.43 (5)Cl1—K—Cl2v61.00 (4)
Cl3—Nb—Cl182.62 (3)Cl1xiii—K—Cl2v93.03 (7)
Cl3i—Nb—Cl180.56 (3)Cl2x—K—Cl2v59.26 (8)
Cl2ii—Nb—Cl182.43 (3)Cl1xii—K—Cl2xiv93.03 (7)
Cl2—Nb—Cl180.32 (3)Cl1—K—Cl2xiv120.15 (11)
Cl3—Nb—Nbi95.50 (3)Cl1xiii—K—Cl2xiv61.00 (4)
Cl3i—Nb—Nbi53.45 (3)Cl2x—K—Cl2xiv59.26 (8)
Cl2ii—Nb—Nbi143.55 (3)Cl2v—K—Cl2xiv59.26 (8)
Cl2—Nb—Nbi96.08 (3)Cl1xii—K—Cl3vi56.81 (4)
Cl1—Nb—Nbi134.01 (3)Cl1—K—Cl3vi89.81 (7)
Cl3—Nb—Nbiii53.52 (2)Cl1xiii—K—Cl3vi118.80 (11)
Cl3i—Nb—Nbiii96.62 (3)Cl2x—K—Cl3vi108.69 (2)
Cl2ii—Nb—Nbiii96.09 (3)Cl2v—K—Cl3vi145.52 (2)
Cl2—Nb—Nbiii143.54 (3)Cl2xiv—K—Cl3vi146.64 (3)
Cl1—Nb—Nbiii136.13 (3)Cl1xii—K—Cl3xv89.81 (7)
Nbi—Nb—Nbiii60.090 (15)Cl1—K—Cl3xv118.80 (11)
Cl3—Nb—Nbii96.57 (3)Cl1xiii—K—Cl3xv56.81 (4)
Cl3i—Nb—Nbii143.44 (3)Cl2x—K—Cl3xv145.52 (2)
Cl2ii—Nb—Nbii53.55 (3)Cl2v—K—Cl3xv146.64 (3)
Cl2—Nb—Nbii95.92 (2)Cl2xiv—K—Cl3xv108.69 (2)
Cl1—Nb—Nbii135.97 (3)Cl3vi—K—Cl3xv62.01 (8)
Nbi—Nb—Nbii90.0Cl1xii—K—Cl3i118.80 (11)
Nbiii—Nb—Nbii59.955 (8)Cl1—K—Cl3i56.81 (4)
Cl3—Nb—Nbiv143.51 (2)Cl1xiii—K—Cl3i89.81 (7)
Cl3i—Nb—Nbiv95.35 (3)Cl2x—K—Cl3i146.64 (3)
Cl2ii—Nb—Nbiv95.92 (2)Cl2v—K—Cl3i108.69 (2)
Cl2—Nb—Nbiv53.54 (3)Cl2xiv—K—Cl3i145.52 (2)
Cl1—Nb—Nbiv133.85 (3)Cl3vi—K—Cl3i62.01 (8)
Nbi—Nb—Nbiv59.955 (8)Cl3xv—K—Cl3i62.01 (8)
Nbiii—Nb—Nbiv90.0Cl1xii—K—Cl2xii56.33 (2)
Nbii—Nb—Nbiv60.0Cl1—K—Cl2xii63.68 (2)
Y—Cl1—Nb133.42 (4)Cl1xiii—K—Cl2xii175.87 (8)
Y—Cl1—K129.68 (7)Cl2x—K—Cl2xii60.38 (5)
Nb—Cl1—K94.86 (6)Cl2v—K—Cl2xii90.62 (7)
Nbiv—Cl2—Nb72.91 (3)Cl2xiv—K—Cl2xii119.64 (11)
Nbiv—Cl2—Kv106.06 (5)Cl3vi—K—Cl2xii58.15 (4)
Nb—Cl2—Kv106.05 (5)Cl3xv—K—Cl2xii120.13 (11)
Nbiv—Cl2—K134.16 (8)Cl3i—K—Cl2xii90.85 (7)
Nb—Cl2—K96.63 (6)Cl1xii—K—Cl2xiii63.68 (2)
Kv—Cl2—K119.62 (5)Cl1—K—Cl2xiii175.87 (8)
Nb—Cl3—Nbiii73.03 (3)Cl1xiii—K—Cl2xiii56.33 (2)
Nb—Cl3—Kvi136.02 (4)Cl2x—K—Cl2xiii90.62 (7)
Nbiii—Cl3—Kvi97.85 (5)Cl2v—K—Cl2xiii119.64 (11)
Cl1—Y—Cl1vii90.47 (3)Cl2xiv—K—Cl2xiii60.38 (5)
Cl1—Y—Cl1viii90.47 (3)Cl3vi—K—Cl2xiii90.85 (7)
Cl1vii—Y—Cl1viii90.47 (3)Cl3xv—K—Cl2xiii58.15 (4)
Cl1—Y—Cl1ix180.0Cl3i—K—Cl2xiii120.13 (11)
Cl1vii—Y—Cl1ix89.53 (3)Cl2xii—K—Cl2xiii119.998 (1)
Cl1viii—Y—Cl1ix89.53 (3)Cl1xii—K—Cl2175.87 (8)
Cl1—Y—Cl1x89.53 (3)Cl1—K—Cl256.33 (2)
Cl1vii—Y—Cl1x180.0Cl1xiii—K—Cl263.68 (2)
Cl1viii—Y—Cl1x89.53 (3)Cl2x—K—Cl2119.64 (11)
Cl1ix—Y—Cl1x90.47 (3)Cl2v—K—Cl260.38 (5)
Cl1—Y—Cl1xi89.53 (3)Cl2xiv—K—Cl290.62 (7)
Cl1vii—Y—Cl1xi89.53 (3)Cl3vi—K—Cl2120.13 (11)
Cl1viii—Y—Cl1xi180.00 (4)Cl3xv—K—Cl290.85 (7)
Cl1ix—Y—Cl1xi90.47 (3)Cl3i—K—Cl258.15 (4)
Cl1x—Y—Cl1xi90.47 (3)Cl2xii—K—Cl2119.998 (1)
Cl1xii—K—Cl1119.919 (8)Cl2xiii—K—Cl2119.998 (1)
Cl1xii—K—Cl1xiii119.919 (8)
Symmetry codes: (i) y, x+y, z; (ii) y, xy, z; (iii) xy, x, z; (iv) x+y, x, z; (v) x1/3, y2/3, z+1/3; (vi) x, y1, z; (vii) x+y+1, x, z; (viii) y, xy1, z; (ix) x+2/3, y2/3, z+1/3; (x) xy1/3, x2/3, z+1/3; (xi) y+2/3, x+y+1/3, z+1/3; (xii) x+y, x1, z; (xiii) y1, xy1, z; (xiv) y1/3, x+y2/3, z+1/3; (xv) xy1, x1, z.

Experimental details

Crystal data
Chemical formulaKYNb6Cl18
Mr1323.57
Crystal system, space groupTrigonal, R3
Temperature (K)293
a, c (Å)9.2527 (6), 25.410 (2)
V3)1884.0 (2)
Z3
Radiation typeMo Kα
µ (mm1)7.00
Crystal size (mm)0.20 × 0.17 × 0.15
Data collection
DiffractometerBruker P4
diffractometer
Absorption correctionEmpirical (using intensity measurements)
via ψ scan (North et al., 1968)
Tmin, Tmax0.709, 0.965
No. of measured, independent and
observed [I > 2σ(I)] reflections
1803, 1342, 1045
Rint0.028
(sin θ/λ)max1)0.725
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.050, 1.03
No. of reflections1342
No. of parameters42
Δρmax, Δρmin (e Å3)0.77, 0.90

Computer programs: XSCANS (Siemens, 1996), XSCANS, SHELXTL (Bruker, 1999), SHELXTL.

Selected geometric parameters (Å, º) top
Nb—Cl32.4476 (10)Nb—Nbii2.9182 (6)
Nb—Cl22.4556 (10)Cl1—Y2.6414 (10)
Nb—Cl12.6497 (10)Cl1—K3.4520 (11)
Nb—Nbi2.9143 (6)Cl2—K3.5292 (10)
Nbi—Nb—Nbiii60.090 (15)Nb—Cl3—Nbiii73.03 (3)
Symmetry codes: (i) y, x+y, z; (ii) y, xy, z; (iii) xy, x, z.
 

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