# Crystal structure of Cs2GdNb6Cl15O3 in the structural evolution of niobium oxychlorides with octa-hedral Nb6-cluster units

Saronom Silaban, Maefa Eka Haryani, Fakhili Gulo, Christiane Perrin

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Saronom Silaban, Maefa Eka Haryani, Fakhili Gulo, Christiane Perrin. Crystal structure of Cs2GdNb6Cl15O3 in the structural evolution of niobium oxychlorides with octa-hedral Nb6-cluster units. Acta crystallographica Section E: Crystallographic communications [2015-..], 2023, Acta Crystallographica Section E-Crystallographic Communications, 79, pp.1008-1011. 10.1107/S205698902300871X. hal-04338523

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Acta Cryst.

E

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN 2056-9890

Received 21 August 2023

Accepted 4 October 2023

Edited by M. Weil, Vienna University of Technology, Austria

**Keywords:** cluster compound; crystal structure; valence electron count.

CCDC reference: 2299097

**Supporting information:** this article has
supporting information at journals.iucr.org/e

# Crystal structure of Cs₂GdNb₆Cl₁₅O₃ in the structural evolution of niobium oxychlorides with octahedral Nb₆-cluster units

Saronom Silaban,ª Maefa Eka Haryani,ᵇ Fakhili Guloᶜ* and Christiane Perrinᵈ

ªDepartment of Chemistry, Medan State University, Medan 20221, Indonesia, ᵇDepartment of Chemistry Education, Sriwijaya University, Inderalaya, Ogan Ilir 30662, South Sumatra, Indonesia, ᶜStudy Program of Environmental Science, Postgraduate Program, Sriwijaya University, Palembang 30139, South Sumatra, Indonesia, and ᵈInstitut de Chimie de Rennes, Laboratoire de Chimie du Solide et Inorganique Moleculaire, UMR 6511, CNRS-Université de Rennes 1, Avenue du Général Leclerc, 35042 Rennes Cedex, France. *Correspondence e-mail: fgulo@unsri.ac.id

Cs₂GdNb₆Cl₁₅O₃, dicaesium gadolinium hexaniobium pentadecachloride trioxide, was synthesized by solid-state reactions starting from a stoichiometric mixture of CsCl, Gd₂O₃, Nb, NbCl₅, and Nb₂O₅. The crystal structure is based on octahedral Nb₆ cluster units (point group symmetry 3.2) with composition [(Nb₆Clᵢ₉Oᵢ₃)Cl₆]⁵⁻ where i and a denote inner and outer ligands. Cs₂GdNb₆Cl₁₅O₃ exhibits 14 valence electrons per cluster unit. The cluster units are linked to each other by CsI and GdIII atoms, whereby CsI (site symmetry 3..) is 12-coordinated by six Clᵢ and six Clᵃ ligands belonging to six neighboring cluster units and GdIII (site symmetry 3.2) is 9-coordinated by three Oᵢ and six Clᵢ ligands belonging to three adjacent cluster units. The arrangement of cluster units corresponds to a stacking of ...AA'A'... layers along [001]. Cs₂GdNb₆Cl₁₅O₃ is isotypic with Cs₂UNb₆Cl₁₅O₃.

## 1. Chemical context

Transition-metal clusters have high potentials and synergetic effects in the fields of biotechnology, catalysis, or sensor applications (Nguyen *et al.*, 2022). The use of these clusters as supramolecular building units is advantageous because of their unique structural, chemical and physical properties (Zhou & Lachgar, 2007). For example, charge-transfer (CT) solids with an anti-perovskite crystal structure have been derived from molybdenum cluster units by electro-crystalization (Hiramatsu *et al.*, 2015), or octahedral cluster units of niobium have been widely used as raw materials for the preparation of novel compounds with interesting structures and magnetic properties (Naumov *et al.*, 2003; Zhang *et al.*, 2011).

A large number of binary, ternary and quaternary niobium compounds with octahedral clusters based on the [Nb₆L'₁₂Lᵃ₆] unit (L = halogen or oxygen ligands) have been reported previously (Perrin *et al.*, 2001). In this cluster unit, the edge of the Nb₆ octahedron is bridged by twelve inner ligands (L') while the other six outer ligands (Lª) are located at apical positions (Schäfer & von Schnering, 1964). The number of electrons involved in the formation of metal-metal bonds in the cluster is called the valence electron count (VEC). The ideal VEC value per cluster is 16 for chloride compounds and 14 for oxide compounds. In chlorides, the cluster units are interlinked by involving outer ligands (Perrin, 1997), whereas in oxides, the connectivity between the units is achieved through the inner ligands (Köhler *et al.*, 1991).

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Mixing of halogen and oxygen as ligands for Nb₆ cluster compounds is a very interesting topic for in-depth studies to enrich our knowledge about new materials and their physical and chemical properties. It has been reported that the structural, magnetic and electronic properties of octahedral clusters of niobium oxychlorides are influenced by oxygen ligands (Fontaine et al., 2011). In this respect, preparation and characterization of new oxychloride compounds with octahedral Nb₆ clusters were reported by Perrin et al. with one O[i (Cordier et al., 1996), two O[i (Gulo & Perrin, 2000), three O[i (Cordier et al., 1994, 1997; Gulo & Perrin, 2002), and six O[i (Gulo et al., 2001) ligands per cluster unit. Other oxychloride compounds containing four O[i (Anokhina et al., 1998, 2000) and six O[i (Anokhina et al., 2001) ligands per cluster unit are also known.

The niobium oxychloride compound Cs₂UNb₆Cl₁₅O₃ was synthesized and structurally characterized many years ago (Cordier et al., 1997). We have now prepared a related compound with composition Cs₂GdNb₆Cl₁₅O₃ and have determined its crystal structure where gadolinium occupies the same position as uranium in the previous compound. In the current communication, the crystal structure, interatomic distances, and the role of monovalent and trivalent cations in Cs₂GdNb₆Cl₁₅O₃ are compared with other niobium oxychlorides containing octahedral Nb₆ clusters.

## 2. Structural commentary

The structure of Cs₂GdNb₆Cl₁₅O₃ is isotypic with Cs₂UNb₆Cl₁₅O₃ and displays the Nb₆ octahedron as the basic cluster motif. The asymmetric unit comprises seven sites: one Cs (site symmetry 3.., multiplicity 4, Wyckoff letter *e*), one Gd (3.2, 2 *c*), one Nb (1, 12 *i*), one O (..2, 6 *h*) and three Cl (Cl1: 6 *h*; Cl2 12 *i*; Cl3: 12 *i*). Six symmetry-equivalent niobium atoms build up the octahedral cluster (centered at a position with site symmetry 3.2, 2 *a*). Each niobium atom is surrounded by one oxygen (O) inner-ligand, three chlorine (Cl1 and Cl2) inner-ligands, and one chlorine (Cl3) outer-ligand. Every edge of the

Nb₆ octahedron is bridged by a chlorine or oxygen ligand as inner-ligands, and six other chlorine ligands are attached in apical positions as outer ligands, as shown in Fig. 1. This cluster motif can be written as a developed unit, [(Nb₆Cl'₉O'₃)Cl'₆]⁵⁻.

The length of the intracluster Nb—Nb bonds range from 2.7686 (5) to 3.0317 (5) Å corresponding to the edge bridged by the O[i and Cl[i ligands, respectively; the average bond length is 2.954 Å. Thus, the Nb₆ octahedron undergoes distortions as observed in other niobium oxychloride compounds. The Nb—Nb distances in this compound are significantly shorter than those observed in other compounds containing two or fewer O[i ligands but are significantly longer than those observed in compounds containing four or more O[i ligands (Gulo & Perrin, 2012). In the various oxychloride compounds that have been isolated so far, it seems that an increase in the number of O[i ligands per formula leads to a decrease in the length of intracluster Nb—Nb bonds. This difference is due to a stronger steric effect as observed, for example, in PbLu₃Nb₆Cl₁₅O₆ (Gulo et al., 2001) with six O[i ligands. Cs₂GdNb₆Cl₁₅O₃ has three O[i ligands per cluster. They are localized at *trans*-inner positions relative to the Nb₆ cluster, similar to the arrangement of three O[i ligands in Na₀.₂₁Nb₆Cl₁₀.₅O₃ where the cluster exhibits point group symmetry 3 (Gulo & Perrin, 2002). In contrast, the three O[i ligands in ScNb₆Cl₁₃O₃ occupy a *cis*-inner position relative to the Nb₆ octahedron to produce a cluster motif with 2 symmetry (Cordier et al., 1994). In the title compound, the Nb₆ clusters are arranged in (001) layers with an ...AA'A'... stacking along [001] (Fig. 2).

<figure><img src="image_6.png" /><figcaption>**Figure 1**
The [(Nb₆Cl'₉O'₃)Cl'₆]⁵⁻ unit in the crystal structure of Cs₂GdNb₆Cl₁₅O₃. Displacement ellipsoids are shown at the 60% probability level.</figcaption></figure>

<figure><img src="image_7.png" /><figcaption>**Figure 2**
The ...AA'A'... stacking of the Nb₆ clusters in the crystal structure of Cs₂GdNb₆Cl₁₅O₃. Cl and O atoms are omitted for clarity.</figcaption></figure>
The Nb—Cl^i distances vary from 2.4543 (7) Å to 2.4802 (7) Å (average 2.468 Å) while the Nb—Cl^a bond is longer, 2.5728 (7) Å. In general, the Nb—L (L = O, Cl) bond lengths in Cs₂GdNb₆Cl₁₅O₃ are not significantly different from that of other niobium oxychloride compounds (Naumov *et al.*, 2003).

In the crystal structure of Cs₂GdNb₆Cl₁₅O₃, the [(Nb₆Cl⁴⁻O³⁻)Cl⁴⁻]⁵⁻ units are interconnected through the Cs¹ and GdIII atoms that are located in between the layers of Nb₆ clusters (Fig. 2). The existence of such discrete cluster units or the absence of intercluster connectivity has also been observed in PbLu₃Nb₆Cl₁₅O₆ (Gulo *et al.*, 2001) and Cs₂Ti₄Nb₆Cl₁₈O₆ (Anokhina *et al.*, 2001) where Nb₆-clusters likewise are formed by six symmetry-equivalent Nb atoms in contrast to CsNb₆Cl₁₂O₂ (Gulo & Perrin, 2000) where the Nb₆-octahedron is formed by three different Nb atoms. In the crystal structure of the latter, the cluster units are linked together via bridging O and Cl ligands.

The GdIII atom in Cs₂GdNb₆Cl₁₅O₃ has a coordination number of 9, defined by three O^i and six Cl^a ligands provided by three nearby cluster units (Fig. 3), with bond lengths of Gd—O = 2.322 (3) Å and Gd—Cl = 3.0994 (8) Å. In comparison, in the crystal structure of PbLu₃Nb₆Cl₁₅O₆, the LuIII atom is surrounded by only six ligands, viz. two O and four Cl atoms, defining Lu₂Cl₂ entities (Gulo *et al.*, 2001). The Nb₆-clusters in PbLu₃Nb₆Cl₁₅O₆ connect to each other via these Lu₂Cl₂ entities whereby each cluster is surrounded by six Lu₂Cl₂ entities, and each of them bridging four adjacent clusters via O and Cl ligands. A related motif is found in Ti₂Nb₆Cl₁₄O₄ where TiIII atoms form zigzag chains of edge-sharing [TiCl₄O₂] octahedra (Anokhina *et al.*, 2000). In other cases, the trivalent ions, such as ScIII in ScNb₆Cl₁₃O₃ (Cordier *et al.*, 1994) or TiIII in Cs₂Ti₃Nb₁₂Cl₂₇O₈ (Anokhina *et al.*, 2000), have a coordination number of five, defined by three O

and two Cl ligands. In another case, the GdIII atom in RbGdNb₆Cl₁₈ is octahedrally surrounded by six Cl ligands from six neighboring cluster units (Gulo *et al.*, 2023). In general, in the series of niobium oxychloride compounds containing octahedral Nb₆ clusters, the crystallographic sites associated with trivalent cations are always fully occupied and are surrounded by Cl and O ligands (Gulo & Perrin, 2012). Only in Cs₂GdNb₆Cl₁₅O₃ and the isotypic uranium analogue, the trivalent cation occupy the center of a triangle formed by three adjacent cluster units and are bonded to nine ligands.

In Cs₂GdNb₆Cl₁₅O₃, the monovalent Cs¹ atom is surrounded by six Nb₆ clusters and coordinated by twelve Cl ligands (Fig. 4). The lengths of Cs—Cl bonds range from 3.5074 (8) to 3.9770 (6) Å. A similar environment around Cs is found in CsNb₆Cl₁₂O₂ with Cs—Cl distances between 3.330 (5) and 3.862 (4) Å (Gulo & Perrin, 2000). In contrast, the Cs¹ atom in Cs₂LuNb₆Cl₁₇O is surrounded by four Nb₆-clusters and is bonded to twelve chlorine ligands with Cs—Cl distances in the range 3.567 (1) to 3.619 (1) Å (Cordier *et al.*, 1996). In RbGdNb₆Cl₁₈ with its smaller monovalent cation RbI, the coordination number is likewise 12. Here, the cation is surrounded also by four Nb₆ clusters, and the Rb—Cl bond lengths range from 3.471 (1) Å to 3.557 (2) Å with an average of 3.512 Å (Gulo *et al.*, 2023). The sites of monovalent cations encountered in the crystal structures of oxychlorides with Nb₆ clusters are always surrounded by Cl ligands with the exception of Cs₂LuNb₆Cl₁₇O where an O atom statistically occupies a site among the twelve inner ligands defining the coordination environment of Cs. On the other hand, the sites associated with the (large) monovalent cation often show partial occupancy. For example, in Na₀.₂₁Nb₆Cl₁₀.₅O₃, the corresponding Na site has an occupancy of only 42.6% (Gulo & Perrin, 2002) and the three Cs sites in Cs₂Ti₄Nb₆Cl₁₈O₆ have occupancies of 38.1%, 57.0% and 6.9% (Anokhina *et al.*, 2001).

<figure><img src="image_8.png" /><figcaption>**Figure 4**
The environment of the Cs¹ atom in Cs₂GdNb₆Cl₁₅O₃.</figcaption></figure>

<figure><img src="image_9.png" /><figcaption>**Figure 3**
The environment of the GdIII atom in Cs₂GdNb₆Cl₁₅O₃.</figcaption></figure>
<table><caption>**Table 1**
Experimental details.</caption><tbody><tr><td colspan="2">Crystal data</td></tr><tr><td>Chemical formula</td><td>Cs<sub>2</sub>GdNb<sub>6</sub>Cl<sub>15</sub>O<sub>3</sub></td></tr><tr><td>M<sub>r</sub></td><td>1560.28</td></tr><tr><td>Crystal system, space group</td><td>Trigonal, <i>P</i>3̄1c</td></tr><tr><td>Temperature (K)</td><td>293</td></tr><tr><td>a, c (Å)</td><td>9.1318 (1), 17.1558 (2)</td></tr><tr><td>V (Å<sup>3</sup>)</td><td>1238.95 (3)</td></tr><tr><td>Z</td><td>2</td></tr><tr><td>Radiation type</td><td>Mo Kα</td></tr><tr><td>μ (mm<sup>-1</sup>)</td><td>9.83</td></tr><tr><td>Crystal size (mm)</td><td>0.08 × 0.07 × 0.05</td></tr><tr><td colspan="2">Data collection</td></tr><tr><td>Diffractometer</td><td>Nonius KappaCCD</td></tr><tr><td>Absorption correction</td><td>Multi-scan (DENZO and SCALEPACK; Otwinowski & Minor, 1997)</td></tr><tr><td>T<sub>min</sub>, T<sub>max</sub></td><td>0.004, 0.017</td></tr><tr><td>No. of measured, independent and observed [I > 2σ(I)] reflections</td><td>7607, 2020, 1790</td></tr><tr><td>R<sub>int</sub></td><td>0.026</td></tr><tr><td>(sin θ/λ)<sub>max</sub> (Å<sup>-1</sup>)</td><td>0.833</td></tr><tr><td colspan="2">Refinement</td></tr><tr><td>R[F<sup>2</sup> > 2σ(F<sup>2</sup>)], wR(F<sup>2</sup>), S</td><td>0.029, 0.068, 1.15</td></tr><tr><td>No. of reflections</td><td>2020</td></tr><tr><td>No. of parameters</td><td>44</td></tr><tr><td>Δρ<sub>max</sub>, Δρ<sub>min</sub> (e Å<sup>-3</sup>)</td><td>1.38, -1.35</td></tr></tbody></table>

Computer programs: COLLECT (Nonius, 1999), SHELXT (Sheldrick, 2015a), SHELXL (Sheldrick, 2015b), DIAMOND (Brandenburg, 2014), and publCIF (Westrip, 2010).

The VEC in Cs₂GdNb₆Cl₁₅O₃ is 14 per cluster unit, as observed in most oxide (Köhler et al., 1991) and oxychloride compounds (Gulo & Perrin, 2012). The number of Oᵢ ligands per cluster can affect the VEC value. Compounds containing one Oᵢ ligand (Cordier et al., 1996) or two Oᵢ ligands (Gulo & Perrin, 2000) exhibit VEC values of 16 and 15. However, niobium oxychloride compounds containing three or more Oᵢ ligands per cluster unit have always a VEC of 14 per cluster unit.

### 3. Synthesis and crystallization

Cs₂GdNb₆Cl₁₅O₃ was prepared by solid-state reactions, starting from a stoichiometric mixture of CsCl (Prolabo, purity 99.5%), Gd₂O₃ (Rhône Poulenc), Nb₂O₅ (Merck, Optipur), NbCl₅ (Ventron, purity 99.998%) and niobium powder (Ventron, purity 99.8%). A total of 300 mg of the mixture was mashed and then loaded in a silica tube under argon atmosphere in a glove box. The silica tube sample was then sealed under vacuum condition. The sample was heated in a vertical heating furnace at 973 K for two days, followed by slow cooling to room temperature. Brown single crystals with a block-like form suitable for structural determination were obtained this way.

### 4. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. The remaining maximum and minimum electron density peaks are located 0.19 Å from Nb and 0.54 Å from Cs, respectively.

## Acknowledgements

The authors thank T. Roisnel, Centre de Diffractométrie de l'Université de Rennes 1, France, for the data collection on the Enraf-Nonius KappaCCD X-ray diffractometer.

## Funding information

The authors wish to thank the Research Institute of Sriwijaya University for research funding.

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# supporting information

Acta Cryst. (2023). E79, 1008-1011 [https://doi.org/10.1107/S205698902300871X]

## Crystal structure of Cs₂GdNb₆Cl₁₅O₃ in the structural evolution of niobium oxychlorides with octahedral Nb₆-cluster units

Saronom Silaban, Maefa Eka Haryani, Fakhili Gulo and Christiane Perrin

### Computing details

Data collection: COLLECT (Nonius, 1999); cell refinement: COLLECT (Nonius, 1999); data reduction: COLLECT (Nonius, 1999); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg, 2014); software used to prepare material for publication: publCIF (Westrip, 2010).

### (I)

#### Crystal data

Cs₂GdNb₆Cl₁₅O₃

$M_r = 1560.28$

Trigonal, $P\bar{3}1c$

$a = 9.1318 (1) Å$

$c = 17.1558 (2) Å$

$V = 1238.95 (3) Å³$

$Z = 2$

$F(000) = 1398$

$D_x = 4.182 \text{ Mg m}^{-3}$

Mo Kα radiation, $\lambda = 0.71073$ Å

Cell parameters from 25 reflections

$\theta = 12-18°$

$\mu = 9.83 \text{ mm}^{-1}$

$T = 293 K$

Block, brown

$0.08 \times 0.07 \times 0.05 \text{ mm}$

#### Data collection

Nonius KappaCCD
diffractometer

Radiation source: fine-focus sealed tube

$\omega$ scans

Absorption correction: multi-scan
(DENZO and SCALEPACK; Otwinowski &
Minor, 1997)

$T_{\text{min}} = 0.004, T_{\text{max}} = 0.017$

7607 measured reflections

2020 independent reflections

1790 reflections with $I > 2\sigma(I)$

$R_{\text{int}} = 0.026$

$\theta_{\text{max}} = 36.3°, \theta_{\text{min}} = 2.4°$

$h = -15 \rightarrow 15$

$k = -12 \rightarrow 12$

$l = -27 \rightarrow 28$

#### Refinement

Refinement on $F^2$

Least-squares matrix: full

$R[F^2 > 2\sigma(F^2)] = 0.029$

$wR(F^2) = 0.068$

$S = 1.15$

2020 reflections

44 parameters

0 restraints

Primary atom site location: structure-invariant
direct methods

Secondary atom site location: difference Fourier
map

$w = 1/[\sigma^2(F_o^2) + (0.0258P)^2 + 3.5848P]$

$\langle\Delta/\sigma\rangle_{\text{max}} = 0.001$

$\Delta\rho_{\text{max}} = 1.38 \text{ e Å}^{-3}$

$\Delta\rho_{\text{min}} = -1.35 \text{ e Å}^{-3}$

Extinction correction: SHELXL2018/3
(Sheldrick, 2015b),
$F^* = kF^2[1+0.001xF^2\lambda^3/\sin(2\theta)]^{-1/4}$

Extinction coefficient: 0.00259 (19)
Special details

**Geometry.** All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

<table><caption>Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²)</caption><thead><tr><th></th><th>x</th><th>y</th><th>z</th><th>U<sub>iso</sub>*/U<sub>eq</sub></th></tr></thead><tbody><tr><td>Cs</td><td>0.333333</td><td>0.666667</td><td>0.54654 (2)</td><td>0.02645 (9)</td></tr><tr><td>Gd</td><td>0.666667</td><td>0.333333</td><td>0.750000</td><td>0.01649 (8)</td></tr><tr><td>Nb</td><td>0.19768 (3)</td><td>0.01608 (3)</td><td>0.68239 (2)</td><td>0.01105 (7)</td></tr><tr><td>Cl1</td><td>0.21283 (6)</td><td>-0.21283 (6)</td><td>0.750000</td><td>0.01643 (17)</td></tr><tr><td>Cl2</td><td>0.01675 (8)</td><td>-0.20367 (8)</td><td>0.58643 (4)</td><td>0.01569 (12)</td></tr><tr><td>Cl3</td><td>0.47649 (9)</td><td>0.07637 (10)</td><td>0.61760 (5)</td><td>0.02252 (15)</td></tr><tr><td>O</td><td>0.3730 (3)</td><td>0.18650 (17)</td><td>0.750000</td><td>0.0142 (5)</td></tr></tbody></table>

<table><caption>Atomic displacement parameters (Å²)</caption><thead><tr><th></th><th>U<sup>11</sup></th><th>U<sup>22</sup></th><th>U<sup>33</sup></th><th>U<sup>12</sup></th><th>U<sup>13</sup></th><th>U<sup>23</sup></th></tr></thead><tbody><tr><td>Cs</td><td>0.02466 (12)</td><td>0.02466 (12)</td><td>0.03002 (19)</td><td>0.01233 (6)</td><td>0.000</td><td>0.000</td></tr><tr><td>Gd</td><td>0.00919 (9)</td><td>0.00919 (9)</td><td>0.03108 (19)</td><td>0.00460 (5)</td><td>0.000</td><td>0.000</td></tr><tr><td>Nb</td><td>0.00836 (10)</td><td>0.00944 (10)</td><td>0.01540 (12)</td><td>0.00448 (7)</td><td>0.00090 (7)</td><td>0.00034 (7)</td></tr><tr><td>Cl1</td><td>0.0149 (3)</td><td>0.0149 (3)</td><td>0.0233 (4)</td><td>0.0103 (3)</td><td>0.0031 (3)</td><td>0.0031 (3)</td></tr><tr><td>Cl2</td><td>0.0144 (3)</td><td>0.0143 (3)</td><td>0.0180 (3)</td><td>0.0068 (2)</td><td>0.0007 (2)</td><td>-0.0028 (2)</td></tr><tr><td>Cl3</td><td>0.0177 (3)</td><td>0.0231 (3)</td><td>0.0298 (4)</td><td>0.0125 (3)</td><td>0.0090 (3)</td><td>0.0033 (3)</td></tr><tr><td>O</td><td>0.0092 (10)</td><td>0.0139 (9)</td><td>0.0179 (13)</td><td>0.0046 (5)</td><td>0.000</td><td>-0.0004 (8)</td></tr></tbody></table>

<table><caption>Geometric parameters (Å, °)</caption><tbody><tr><td>Cs—Cl3<sup>i</sup></td><td>3.5074 (8)</td><td>Gd—Cl3</td><td>3.0994 (8)</td></tr><tr><td>Cs—Cl3<sup>ii</sup></td><td>3.5074 (8)</td><td>Gd—Cl3<sup>viii</sup></td><td>3.0994 (8)</td></tr><tr><td>Cs—Cl3<sup>iii</sup></td><td>3.5074 (8)</td><td>Gd—Cl3<sup>vii</sup></td><td>3.0994 (8)</td></tr><tr><td>Cs—Cl3<sup>iv</sup></td><td>3.5180 (8)</td><td>Gd—Cl3<sup>ix</sup></td><td>3.0994 (8)</td></tr><tr><td>Cs—Cl3<sup>v</sup></td><td>3.5180 (8)</td><td>Gd—Cl3<sup>x</sup></td><td>3.0994 (8)</td></tr><tr><td>Cs—Cl3<sup>vi</sup></td><td>3.5180 (8)</td><td>Gd—Cl3<sup>iii</sup></td><td>3.0994 (8)</td></tr><tr><td>Cs—Cl2<sup>i</sup></td><td>3.6948 (7)</td><td>Nb—O</td><td>1.9593 (19)</td></tr><tr><td>Cs—Cl2<sup>iii</sup></td><td>3.6948 (7)</td><td>Nb—Cl1</td><td>2.4543 (7)</td></tr><tr><td>Cs—Cl2<sup>ii</sup></td><td>3.6948 (7)</td><td>Nb—Cl2<sup>ii</sup></td><td>2.4684 (7)</td></tr><tr><td>Cs—Cl1<sup>iii</sup></td><td>3.9770 (6)</td><td>Nb—Cl2</td><td>2.4802 (7)</td></tr><tr><td>Cs—Cl1<sup>ii</sup></td><td>3.9770 (6)</td><td>Nb—Cl3</td><td>2.5728 (7)</td></tr><tr><td>Cs—Cl1<sup>i</sup></td><td>3.9770 (5)</td><td>Nb—Nb<sup>x</sup></td><td>2.7686 (5)</td></tr><tr><td>Gd—O</td><td>2.322 (3)</td><td>Nb—Nb<sup>xi</sup></td><td>3.0075 (4)</td></tr><tr><td>Gd—O<sup>vii</sup></td><td>2.322 (3)</td><td>Nb—Nb<sup>ii</sup></td><td>3.0075 (4)</td></tr><tr><td>Gd—O<sup>iii</sup></td><td>2.322 (3)</td><td>Nb—Nb<sup>xii</sup></td><td>3.0317 (5)</td></tr><tr><td>Cl3<sup>i</sup>—Cs—Cl3<sup>ii</sup></td><td>108.589 (15)</td><td>O<sup>iii</sup>—Gd—Cl3<sup>vii</sup></td><td>80.189 (14)</td></tr><tr><td>Cl3<sup>i</sup>—Cs—Cl3<sup>iii</sup></td><td>108.589 (15)</td><td>Cl3—Gd—Cl3<sup>vii</sup></td><td>72.21 (2)</td></tr></tbody></table>
<table>
  <tbody>
    <tr>
      <td>Cl3<sup>ii</sup>—Cs—Cl3<sup>iii</sup></td>
      <td>108.589 (15)</td>
    </tr>
    <tr>
      <td>Cl3<sup>i</sup>—Cs—Cl3<sup>iv</sup></td>
      <td>108.89 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>ii</sup>—Cs—Cl3<sup>iv</sup></td>
      <td>76.72 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iii</sup>—Cs—Cl3<sup>iv</sup></td>
      <td>137.786 (19)</td>
    </tr>
    <tr>
      <td>Cl3<sup>i</sup>—Cs—Cl3<sup>v</sup></td>
      <td>76.72 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>ii</sup>—Cs—Cl3<sup>v</sup></td>
      <td>137.786 (19)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iii</sup>—Cs—Cl3<sup>v</sup></td>
      <td>108.89 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iv</sup>—Cs—Cl3<sup>v</sup></td>
      <td>62.55 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>i</sup>—Cs—Cl3<sup>vi</sup></td>
      <td>137.786 (19)</td>
    </tr>
    <tr>
      <td>Cl3<sup>ii</sup>—Cs—Cl3<sup>vi</sup></td>
      <td>108.89 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iii</sup>—Cs—Cl3<sup>vi</sup></td>
      <td>76.72 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iv</sup>—Cs—Cl3<sup>vi</sup></td>
      <td>62.55 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>v</sup>—Cs—Cl3<sup>vi</sup></td>
      <td>62.55 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>i</sup>—Cs—Cl2<sup>i</sup></td>
      <td>61.822 (15)</td>
    </tr>
    <tr>
      <td>Cl3<sup>ii</sup>—Cs—Cl2<sup>i</sup></td>
      <td>54.828 (15)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iii</sup>—Cs—Cl2<sup>i</sup></td>
      <td>148.77 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iv</sup>—Cs—Cl2<sup>i</sup></td>
      <td>69.076 (17)</td>
    </tr>
    <tr>
      <td>Cl3<sup>v</sup>—Cs—Cl2<sup>i</sup></td>
      <td>97.986 (17)</td>
    </tr>
    <tr>
      <td>Cl3<sup>vi</sup>—Cs—Cl2<sup>i</sup></td>
      <td>131.531 (19)</td>
    </tr>
    <tr>
      <td>Cl3<sup>i</sup>—Cs—Cl2<sup>iii</sup></td>
      <td>54.828 (15)</td>
    </tr>
    <tr>
      <td>Cl3<sup>ii</sup>—Cs—Cl2<sup>iii</sup></td>
      <td>148.77 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iii</sup>—Cs—Cl2<sup>iii</sup></td>
      <td>61.822 (15)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iv</sup>—Cs—Cl2<sup>iii</sup></td>
      <td>131.531 (19)</td>
    </tr>
    <tr>
      <td>Cl3<sup>v</sup>—Cs—Cl2<sup>iii</sup></td>
      <td>69.076 (18)</td>
    </tr>
    <tr>
      <td>Cl3<sup>vi</sup>—Cs—Cl2<sup>iii</sup></td>
      <td>97.986 (17)</td>
    </tr>
    <tr>
      <td>Cl2<sup>i</sup>—Cs—Cl2<sup>iii</sup></td>
      <td>116.649 (8)</td>
    </tr>
    <tr>
      <td>Cl3<sup>i</sup>—Cs—Cl2<sup>ii</sup></td>
      <td>148.77 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>ii</sup>—Cs—Cl2<sup>ii</sup></td>
      <td>61.822 (15)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iii</sup>—Cs—Cl2<sup>ii</sup></td>
      <td>54.828 (15)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iv</sup>—Cs—Cl2<sup>ii</sup></td>
      <td>97.986 (17)</td>
    </tr>
    <tr>
      <td>Cl3<sup>v</sup>—Cs—Cl2<sup>ii</sup></td>
      <td>131.531 (19)</td>
    </tr>
    <tr>
      <td>Cl3<sup>vi</sup>—Cs—Cl2<sup>ii</sup></td>
      <td>69.076 (17)</td>
    </tr>
    <tr>
      <td>Cl2<sup>i</sup>—Cs—Cl2<sup>ii</sup></td>
      <td>116.649 (8)</td>
    </tr>
    <tr>
      <td>Cl2<sup>iii</sup>—Cs—Cl2<sup>ii</sup></td>
      <td>116.649 (8)</td>
    </tr>
    <tr>
      <td>Cl3<sup>i</sup>—Cs—Cl1<sup>iii</sup></td>
      <td>62.628 (14)</td>
    </tr>
    <tr>
      <td>Cl3<sup>ii</sup>—Cs—Cl1<sup>iii</sup></td>
      <td>97.912 (19)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iii</sup>—Cs—Cl1<sup>iii</sup></td>
      <td>53.624 (14)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iv</sup>—Cs—Cl1<sup>iii</sup></td>
      <td>168.335 (15)</td>
    </tr>
    <tr>
      <td>Cl3<sup>v</sup>—Cs—Cl1<sup>iii</sup></td>
      <td>119.844 (17)</td>
    </tr>
    <tr>
      <td>Cl3<sup>vi</sup>—Cs—Cl1<sup>iii</sup></td>
      <td>129.093 (15)</td>
    </tr>
    <tr>
      <td>Cl2<sup>i</sup>—Cs—Cl1<sup>iii</sup></td>
      <td>99.332 (16)</td>
    </tr>
    <tr>
      <td>Cl2<sup>iii</sup>—Cs—Cl1<sup>iii</sup></td>
      <td>51.659 (16)</td>
    </tr>
    <tr>
      <td>Cl2<sup>ii</sup>—Cs—Cl1<sup>iii</sup></td>
      <td>88.306 (13)</td>
    </tr>
    <tr>
      <td>Cl3<sup>i</sup>—Cs—Cl1<sup>ii</sup></td>
      <td>97.912 (19)</td>
    </tr>
    <tr>
      <td>Cl3<sup>ii</sup>—Cs—Cl1<sup>ii</sup></td>
      <td>53.623 (14)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iii</sup>—Cs—Cl1<sup>ii</sup></td>
      <td>62.629 (14)</td>
    </tr>
    <tr>
      <td>Cl3<sup>iv</sup>—Cs—Cl1<sup>ii</sup></td>
      <td>129.092 (15)</td>
    </tr>
    <tr>
      <td>Cl3<sup>v</sup>—Cs—Cl1<sup>ii</sup></td>
      <td>168.336 (16)</td>
    </tr>
  </tbody>
</table>

<table>
  <tbody>
    <tr>
      <td>Cl3<sup>viii</sup>—Gd—Cl3<sup>vii</sup></td>
      <td>98.06 (3)</td>
    </tr>
    <tr>
      <td>O—Gd—Cl3<sup>ix</sup></td>
      <td>80.189 (13)</td>
    </tr>
    <tr>
      <td>O<sup>vii</sup>—Gd—Cl3<sup>ix</sup></td>
      <td>60.971 (13)</td>
    </tr>
    <tr>
      <td>O<sup>iii</sup>—Gd—Cl3<sup>ix</sup></td>
      <td>130.969 (15)</td>
    </tr>
    <tr>
      <td>Cl3—Gd—Cl3<sup>ix</sup></td>
      <td>98.06 (3)</td>
    </tr>
    <tr>
      <td>Cl3<sup>viii</sup>—Gd—Cl3<sup>ix</sup></td>
      <td>72.21 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>vii</sup>—Gd—Cl3<sup>ix</sup></td>
      <td>121.94 (2)</td>
    </tr>
    <tr>
      <td>O—Gd—Cl3<sup>x</sup></td>
      <td>60.971 (13)</td>
    </tr>
    <tr>
      <td>O<sup>vii</sup>—Gd—Cl3<sup>x</sup></td>
      <td>130.969 (14)</td>
    </tr>
    <tr>
      <td>O<sup>iii</sup>—Gd—Cl3<sup>x</sup></td>
      <td>80.189 (14)</td>
    </tr>
    <tr>
      <td>Cl3—Gd—Cl3<sup>x</sup></td>
      <td>121.94 (3)</td>
    </tr>
    <tr>
      <td>Cl3<sup>viii</sup>—Gd—Cl3<sup>x</sup></td>
      <td>72.21 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>vii</sup>—Gd—Cl3<sup>x</sup></td>
      <td>160.38 (3)</td>
    </tr>
    <tr>
      <td>Cl3<sup>ix</sup>—Gd—Cl3<sup>x</sup></td>
      <td>72.21 (2)</td>
    </tr>
    <tr>
      <td>O—Gd—Cl3<sup>iii</sup></td>
      <td>80.189 (14)</td>
    </tr>
    <tr>
      <td>O<sup>vii</sup>—Gd—Cl3<sup>iii</sup></td>
      <td>130.969 (14)</td>
    </tr>
    <tr>
      <td>O<sup>iii</sup>—Gd—Cl3<sup>iii</sup></td>
      <td>60.971 (13)</td>
    </tr>
    <tr>
      <td>Cl3—Gd—Cl3<sup>iii</sup></td>
      <td>72.20 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>viii</sup>—Gd—Cl3<sup>iii</sup></td>
      <td>121.94 (3)</td>
    </tr>
    <tr>
      <td>Cl3<sup>vii</sup>—Gd—Cl3<sup>iii</sup></td>
      <td>72.21 (2)</td>
    </tr>
    <tr>
      <td>Cl3<sup>ix</sup>—Gd—Cl3<sup>iii</sup></td>
      <td>160.38 (3)</td>
    </tr>
    <tr>
      <td>Cl3<sup>x</sup>—Gd—Cl3<sup>iii</sup></td>
      <td>98.06 (3)</td>
    </tr>
    <tr>
      <td>O—Nb—Cl1</td>
      <td>91.438 (10)</td>
    </tr>
    <tr>
      <td>O—Nb—Cl2<sup>ii</sup></td>
      <td>95.39 (2)</td>
    </tr>
    <tr>
      <td>Cl1—Nb—Cl2<sup>ii</sup></td>
      <td>165.85 (2)</td>
    </tr>
    <tr>
      <td>O—Nb—Cl2</td>
      <td>169.99 (6)</td>
    </tr>
    <tr>
      <td>Cl1—Nb—Cl2</td>
      <td>85.583 (18)</td>
    </tr>
    <tr>
      <td>Cl2<sup>ii</sup>—Nb—Cl2</td>
      <td>85.58 (3)</td>
    </tr>
    <tr>
      <td>O—Nb—Cl3</td>
      <td>75.97 (6)</td>
    </tr>
    <tr>
      <td>Cl1—Nb—Cl3</td>
      <td>85.14 (2)</td>
    </tr>
    <tr>
      <td>Cl2<sup>ii</sup>—Nb—Cl3</td>
      <td>84.52 (2)</td>
    </tr>
    <tr>
      <td>Cl2—Nb—Cl3</td>
      <td>94.24 (3)</td>
    </tr>
    <tr>
      <td>O—Nb—Nb<sup>x</sup></td>
      <td>45.05 (6)</td>
    </tr>
    <tr>
      <td>Cl1—Nb—Nb<sup>x</sup></td>
      <td>94.843 (15)</td>
    </tr>
    <tr>
      <td>Cl2<sup>ii</sup>—Nb—Nb<sup>x</sup></td>
      <td>98.75 (2)</td>
    </tr>
    <tr>
      <td>Cl2—Nb—Nb<sup>x</sup></td>
      <td>144.687 (16)</td>
    </tr>
    <tr>
      <td>Cl3—Nb—Nb<sup>x</sup></td>
      <td>121.017 (19)</td>
    </tr>
    <tr>
      <td>O—Nb—Nb<sup>xi</sup></td>
      <td>137.22 (6)</td>
    </tr>
    <tr>
      <td>Cl1—Nb—Nb<sup>xi</sup></td>
      <td>89.097 (14)</td>
    </tr>
    <tr>
      <td>Cl2<sup>ii</sup>—Nb—Nb<sup>xi</sup></td>
      <td>94.227 (16)</td>
    </tr>
    <tr>
      <td>Cl2—Nb—Nb<sup>xi</sup></td>
      <td>52.396 (17)</td>
    </tr>
    <tr>
      <td>Cl3—Nb—Nb<sup>xi</sup></td>
      <td>146.53 (2)</td>
    </tr>
    <tr>
      <td>Nb<sup>x</sup>—Nb—Nb<sup>xi</sup></td>
      <td>92.291 (4)</td>
    </tr>
    <tr>
      <td>O—Nb—Nb<sup>ii</sup></td>
      <td>94.52 (4)</td>
    </tr>
    <tr>
      <td>Cl1—Nb—Nb<sup>ii</sup></td>
      <td>139.044 (15)</td>
    </tr>
    <tr>
      <td>Cl2<sup>ii</sup>—Nb—Nb<sup>ii</sup></td>
      <td>52.752 (17)</td>
    </tr>
    <tr>
      <td>Cl2—Nb—Nb<sup>ii</sup></td>
      <td>93.982 (16)</td>
    </tr>
    <tr>
      <td>Cl3—Nb—Nb<sup>ii</sup></td>
      <td>135.56 (2)</td>
    </tr>
  </tbody>
</table>
<table>
  <tr>
    <td>Cl3<sup>vi</sup>—Cs—Cl1<sup>ii</sup></td>
    <td>119.844 (17)</td>
    <td>Nb<sup>x</sup>—Nb—Nb<sup>ii</sup></td>
    <td>63.159 (10)</td>
  </tr>
  <tr>
    <td>Cl2<sup>i</sup>—Cs—Cl1<sup>ii</sup></td>
    <td>88.305 (13)</td>
    <td>Nb<sup>xi</sup>—Nb—Nb<sup>ii</sup></td>
    <td>60.0</td>
  </tr>
  <tr>
    <td>Cl2<sup>iii</sup>—Cs—Cl1<sup>ii</sup></td>
    <td>99.332 (16)</td>
    <td>O—Nb—Nb<sup>xii</sup></td>
    <td>93.78 (4)</td>
  </tr>
  <tr>
    <td>Cl2<sup>ii</sup>—Cs—Cl1<sup>ii</sup></td>
    <td>51.660 (16)</td>
    <td>Cl1—Nb—Nb<sup>xii</sup></td>
    <td>51.856 (14)</td>
  </tr>
  <tr>
    <td>Cl1<sup>iii</sup>—Cs—Cl1<sup>ii</sup></td>
    <td>49.043 (19)</td>
    <td>Cl2<sup>ii</sup>—Nb—Nb<sup>xii</sup></td>
    <td>139.534 (16)</td>
  </tr>
  <tr>
    <td>Cl3<sup>i</sup>—Cs—Cl1<sup>i</sup></td>
    <td>53.623 (14)</td>
    <td>Cl2—Nb—Nb<sup>xii</sup></td>
    <td>91.888 (19)</td>
  </tr>
  <tr>
    <td>Cl3<sup>ii</sup>—Cs—Cl1<sup>i</sup></td>
    <td>62.629 (15)</td>
    <td>Cl3—Nb—Nb<sup>xii</sup></td>
    <td>135.895 (19)</td>
  </tr>
  <tr>
    <td>Cl3<sup>iii</sup>—Cs—Cl1<sup>i</sup></td>
    <td>97.912 (19)</td>
    <td>Nb<sup>x</sup>—Nb—Nb<sup>xii</sup></td>
    <td>62.269 (11)</td>
  </tr>
  <tr>
    <td>Cl3<sup>iv</sup>—Cs—Cl1<sup>i</sup></td>
    <td>119.843 (17)</td>
    <td>Nb<sup>xi</sup>—Nb—Nb<sup>xii</sup></td>
    <td>54.570 (9)</td>
  </tr>
  <tr>
    <td>Cl3<sup>v</sup>—Cs—Cl1<sup>i</sup></td>
    <td>129.092 (15)</td>
    <td>Nb<sup>ii</sup>—Nb—Nb<sup>xii</sup></td>
    <td>87.296 (5)</td>
  </tr>
  <tr>
    <td>Cl3<sup>vi</sup>—Cs—Cl1<sup>i</sup></td>
    <td>168.336 (16)</td>
    <td>Nb<sup>xii</sup>—Cl1—Nb</td>
    <td>76.29 (3)</td>
  </tr>
  <tr>
    <td>Cl2<sup>i</sup>—Cs—Cl1<sup>i</sup></td>
    <td>51.659 (16)</td>
    <td>Nb<sup>xii</sup>—Cl1—Cs<sup>xiii</sup></td>
    <td>142.343 (15)</td>
  </tr>
  <tr>
    <td>Cl2<sup>iii</sup>—Cs—Cl1<sup>i</sup></td>
    <td>88.305 (13)</td>
    <td>Nb—Cl1—Cs<sup>xiii</sup></td>
    <td>87.830 (6)</td>
  </tr>
  <tr>
    <td>Cl2<sup>ii</sup>—Cs—Cl1<sup>i</sup></td>
    <td>99.333 (16)</td>
    <td>Nb<sup>xii</sup>—Cl1—Cs<sup>xiv</sup></td>
    <td>87.831 (6)</td>
  </tr>
  <tr>
    <td>Cl1<sup>iii</sup>—Cs—Cl1<sup>i</sup></td>
    <td>49.043 (19)</td>
    <td>Nb—Cl1—Cs<sup>xiv</sup></td>
    <td>142.343 (15)</td>
  </tr>
  <tr>
    <td>Cl1<sup>ii</sup>—Cs—Cl1<sup>i</sup></td>
    <td>49.043 (19)</td>
    <td>Cs<sup>xiii</sup>—Cl1—Cs<sup>xiv</sup></td>
    <td>122.73 (2)</td>
  </tr>
  <tr>
    <td>O—Gd—O<sup>vii</sup></td>
    <td>120.0</td>
    <td>Nb<sup>xi</sup>—Cl2—Nb</td>
    <td>74.85 (2)</td>
  </tr>
  <tr>
    <td>O—Gd—O<sup>iii</sup></td>
    <td>120.0</td>
    <td>Nb<sup>xi</sup>—Cl2—Cs<sup>xiii</sup></td>
    <td>146.20 (3)</td>
  </tr>
  <tr>
    <td>O<sup>vii</sup>—Gd—O<sup>iii</sup></td>
    <td>120.000 (1)</td>
    <td>Nb—Cl2—Cs<sup>xiii</sup></td>
    <td>94.06 (2)</td>
  </tr>
  <tr>
    <td>O—Gd—Cl3</td>
    <td>60.971 (13)</td>
    <td>Nb—Cl3—Gd</td>
    <td>88.01 (2)</td>
  </tr>
  <tr>
    <td>O<sup>vii</sup>—Gd—Cl3</td>
    <td>80.190 (14)</td>
    <td>Nb—Cl3—Cs<sup>xiii</sup></td>
    <td>96.94 (2)</td>
  </tr>
  <tr>
    <td>O<sup>iii</sup>—Gd—Cl3</td>
    <td>130.969 (14)</td>
    <td>Gd—Cl3—Cs<sup>xiii</sup></td>
    <td>146.22 (3)</td>
  </tr>
  <tr>
    <td>O—Gd—Cl3<sup>viii</sup></td>
    <td>130.969 (14)</td>
    <td>Nb—Cl3—Cs<sup>v</sup></td>
    <td>126.46 (3)</td>
  </tr>
  <tr>
    <td>O<sup>vii</sup>—Gd—Cl3<sup>viii</sup></td>
    <td>80.189 (14)</td>
    <td>Gd—Cl3—Cs<sup>v</sup></td>
    <td>100.30 (2)</td>
  </tr>
  <tr>
    <td>O<sup>iii</sup>—Gd—Cl3<sup>viii</sup></td>
    <td>60.971 (13)</td>
    <td>Cs<sup>xiii</sup>—Cl3—Cs<sup>v</sup></td>
    <td>103.28 (2)</td>
  </tr>
  <tr>
    <td>Cl3—Gd—Cl3<sup>viii</sup></td>
    <td>160.38 (3)</td>
    <td>Nb<sup>x</sup>—O—Nb</td>
    <td>89.91 (11)</td>
  </tr>
  <tr>
    <td>O—Gd—Cl3<sup>vii</sup></td>
    <td>130.969 (15)</td>
    <td>Nb<sup>x</sup>—O—Gd</td>
    <td>135.05 (6)</td>
  </tr>
  <tr>
    <td>O<sup>vii</sup>—Gd—Cl3<sup>vii</sup></td>
    <td>60.971 (13)</td>
    <td>Nb—O—Gd</td>
    <td>135.05 (6)</td>
  </tr>
</table>

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